From 2a78b1863aba9bd984ea93e1c55e49b512e115e6 Mon Sep 17 00:00:00 2001
From: Jia Yu <jiayu@apache.org>
Date: Sat, 28 Mar 2026 23:55:34 -0700
Subject: [PATCH 1/5] [GH-2799] Add ST_OffsetCurve function

---
 .../org/apache/sedona/common/Functions.java   | 15 ++++++
 .../apache/sedona/common/FunctionsTest.java   | 46 ++++++++++++++++
 docs/api/flink/Geometry-Functions.md          |  1 +
 .../Geometry-Processing/ST_OffsetCurve.md     | 52 ++++++++++++++++++
 .../vector-data/Geometry-Functions.md         |  1 +
 .../Geometry-Processing/ST_OffsetCurve.md     | 50 +++++++++++++++++
 docs/api/sql/Geometry-Functions.md            |  1 +
 .../sql/Geometry-Processing/ST_OffsetCurve.md | 54 +++++++++++++++++++
 docs/image/ST_OffsetCurve/ST_OffsetCurve.svg  | 34 ++++++++++++
 .../java/org/apache/sedona/flink/Catalog.java |  1 +
 .../sedona/flink/expressions/Functions.java   | 33 ++++++++++++
 .../org/apache/sedona/flink/FunctionTest.java | 18 +++++++
 python/sedona/spark/sql/st_functions.py       | 26 +++++++++
 python/tests/sql/test_dataframe_api.py        | 15 ++++++
 python/tests/sql/test_function.py             | 22 ++++++++
 .../org/apache/sedona/sql/UDF/Catalog.scala   |  1 +
 .../sedona_sql/expressions/Functions.scala    | 10 ++++
 .../sedona_sql/expressions/st_functions.scala |  9 ++++
 .../apache/sedona/sql/PreserveSRIDSuite.scala |  1 +
 .../sedona/sql/dataFrameAPITestScala.scala    | 16 ++++++
 .../apache/sedona/sql/functionTestScala.scala | 20 +++++++
 21 files changed, 426 insertions(+)
 create mode 100644 docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
 create mode 100644 docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
 create mode 100644 docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
 create mode 100644 docs/image/ST_OffsetCurve/ST_OffsetCurve.svg

diff --git a/common/src/main/java/org/apache/sedona/common/Functions.java b/common/src/main/java/org/apache/sedona/common/Functions.java
index fdec8913c37..78bd8740517 100644
--- a/common/src/main/java/org/apache/sedona/common/Functions.java
+++ b/common/src/main/java/org/apache/sedona/common/Functions.java
@@ -54,6 +54,7 @@
 import org.locationtech.jts.linearref.LengthIndexedLine;
 import org.locationtech.jts.operation.buffer.BufferOp;
 import org.locationtech.jts.operation.buffer.BufferParameters;
+import org.locationtech.jts.operation.buffer.OffsetCurve;
 import org.locationtech.jts.operation.distance.DistanceOp;
 import org.locationtech.jts.operation.distance3d.Distance3DOp;
 import org.locationtech.jts.operation.linemerge.LineMerger;
@@ -424,6 +425,20 @@ else if (singleParam[0].equalsIgnoreCase(listBufferParameters[5])) {
     return bufferParameters;
   }
 
+  public static Geometry offsetCurve(Geometry geometry, double distance) {
+    return offsetCurve(geometry, distance, BufferParameters.DEFAULT_QUADRANT_SEGMENTS);
+  }
+
+  public static Geometry offsetCurve(Geometry geometry, double distance, int quadrantSegments) {
+    if (geometry.isEmpty()) {
+      return null;
+    }
+    BufferParameters bufferParameters = new BufferParameters();
+    bufferParameters.setQuadrantSegments(quadrantSegments);
+    OffsetCurve oc = new OffsetCurve(geometry, distance, bufferParameters);
+    return oc.getCurve();
+  }
+
   public static int bestSRID(Geometry geometry) throws IllegalArgumentException {
     // Shift longitudes if geometry crosses dateline
     if (crossesDateLine(geometry)) {
diff --git a/common/src/test/java/org/apache/sedona/common/FunctionsTest.java b/common/src/test/java/org/apache/sedona/common/FunctionsTest.java
index e48f62c5461..9264e7ea5ec 100644
--- a/common/src/test/java/org/apache/sedona/common/FunctionsTest.java
+++ b/common/src/test/java/org/apache/sedona/common/FunctionsTest.java
@@ -4250,6 +4250,52 @@ public void shortestLineSameGeometry() {
     assertEquals(0.0, result.getLength(), 1e-6);
   }
 
+  @Test
+  public void offsetCurvePositiveDistance() throws ParseException {
+    // Offset to the left of a horizontal line
+    Geometry line = Constructors.geomFromWKT("LINESTRING (0 0, 10 0)", 0);
+    Geometry result = Functions.offsetCurve(line, 5.0);
+    String actual = Functions.asWKT(result);
+    assertEquals("LINESTRING (0 5, 10 5)", actual);
+  }
+
+  @Test
+  public void offsetCurveNegativeDistance() throws ParseException {
+    // Offset to the right of a horizontal line
+    Geometry line = Constructors.geomFromWKT("LINESTRING (0 0, 10 0)", 0);
+    Geometry result = Functions.offsetCurve(line, -5.0);
+    String actual = Functions.asWKT(result);
+    assertEquals("LINESTRING (0 -5, 10 -5)", actual);
+  }
+
+  @Test
+  public void offsetCurveZeroDistance() throws ParseException {
+    // Zero distance returns a copy of the input
+    Geometry line = Constructors.geomFromWKT("LINESTRING (0 0, 10 0)", 0);
+    Geometry result = Functions.offsetCurve(line, 0.0);
+    String actual = Functions.asWKT(result);
+    assertEquals("LINESTRING (0 0, 10 0)", actual);
+  }
+
+  @Test
+  public void offsetCurveEmptyGeometry() throws ParseException {
+    // Empty geometry returns null
+    Geometry empty = Constructors.geomFromWKT("LINESTRING EMPTY", 0);
+    Geometry result = Functions.offsetCurve(empty, 5.0);
+    assertNull(result);
+  }
+
+  @Test
+  public void offsetCurveWithQuadrantSegments() throws ParseException {
+    // Test with custom quadrant segments
+    Geometry line = Constructors.geomFromWKT("LINESTRING (0 0, 10 0)", 0);
+    Geometry result = Functions.offsetCurve(line, 5.0, 4);
+    assertNotNull(result);
+    // The result should still be a simple offset for a straight line
+    String actual = Functions.asWKT(result);
+    assertEquals("LINESTRING (0 5, 10 5)", actual);
+  }
+
   @Test
   public void testZmFlag() throws ParseException {
     int _2D = 0, _3DM = 1, _3DZ = 2, _4D = 3;
diff --git a/docs/api/flink/Geometry-Functions.md b/docs/api/flink/Geometry-Functions.md
index d0c3f42d5c9..489ebf11f7b 100644
--- a/docs/api/flink/Geometry-Functions.md
+++ b/docs/api/flink/Geometry-Functions.md
@@ -221,6 +221,7 @@ These functions compute geometric constructions, or alter geometry size or shape
 | [ST_LabelPoint](Geometry-Processing/ST_LabelPoint.md) | Geometry | `ST_LabelPoint` computes and returns a label point for a given polygon or geometry collection. The label point is chosen to be sufficiently far from boundaries of the geometry. For a regular Polygo... | v1.7.1 |
 | [ST_MinimumBoundingCircle](Geometry-Processing/ST_MinimumBoundingCircle.md) | Geometry | Returns the smallest circle polygon that contains a geometry. The optional quadrantSegments parameter determines how many segments to use per quadrant and the default number of segments is 48. | v1.5.0 |
 | [ST_MinimumBoundingRadius](Geometry-Processing/ST_MinimumBoundingRadius.md) | Struct | Returns a struct containing the center point and radius of the smallest circle that contains a geometry. | v1.5.0 |
+| [ST_OffsetCurve](Geometry-Processing/ST_OffsetCurve.md) | Geometry | Returns a line at a given offset distance from a linear geometry. Positive distance offsets to the left, negative to the right. | v1.9.0 |
 | [ST_OrientedEnvelope](Geometry-Processing/ST_OrientedEnvelope.md) | Geometry | Returns the minimum-area rotated rectangle enclosing a geometry. The rectangle may be rotated relative to the coordinate axes. Degenerate inputs may result in a Point or LineString being returned. | v1.8.1 |
 | [ST_PointOnSurface](Geometry-Processing/ST_PointOnSurface.md) | Geometry | Returns a POINT guaranteed to lie on the surface. | v1.2.1 |
 | [ST_Polygonize](Geometry-Processing/ST_Polygonize.md) | Geometry | Generates a GeometryCollection composed of polygons that are formed from the linework of an input GeometryCollection. When the input does not contain any linework that forms a polygon, the function... | v1.6.0 |
diff --git a/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md b/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
new file mode 100644
index 00000000000..e00a0a728b3
--- /dev/null
+++ b/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
@@ -0,0 +1,52 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+ -->
+
+# ST_OffsetCurve
+
+Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
+
+The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
+
+Format: `ST_OffsetCurve(geometry: Geometry, distance: Double, quadrantSegments: Integer)`
+
+Format: `ST_OffsetCurve(geometry: Geometry, distance: Double)`
+
+Return type: `Geometry`
+
+Since: `v1.9.0`
+
+SQL Example
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))
+```
+
+Output: `LINESTRING (0 5, 10 5)`
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))
+```
+
+Output: `LINESTRING (0 -5, 10 -5)`
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))
+```
+
+Output: `LINESTRING (0 5, 10 5)`
diff --git a/docs/api/snowflake/vector-data/Geometry-Functions.md b/docs/api/snowflake/vector-data/Geometry-Functions.md
index e22c5d0a308..01ecdda07dc 100644
--- a/docs/api/snowflake/vector-data/Geometry-Functions.md
+++ b/docs/api/snowflake/vector-data/Geometry-Functions.md
@@ -214,6 +214,7 @@ These functions compute geometric constructions, or alter geometry size or shape
 | [ST_MaximumInscribedCircle](Geometry-Processing/ST_MaximumInscribedCircle.md) | Finds the largest circle that is contained within a (multi)polygon, or which does not overlap any lines and points. Returns a row with fields: |
 | [ST_MinimumBoundingCircle](Geometry-Processing/ST_MinimumBoundingCircle.md) | Returns the smallest circle polygon that contains a geometry. |
 | [ST_MinimumBoundingRadius](Geometry-Processing/ST_MinimumBoundingRadius.md) | Returns two columns containing the center point and radius of the smallest circle that contains a geometry. |
+| [ST_OffsetCurve](Geometry-Processing/ST_OffsetCurve.md) | Returns a line at a given offset distance from a linear geometry. Positive distance offsets to the left, negative to the right. |
 | [ST_OrientedEnvelope](Geometry-Processing/ST_OrientedEnvelope.md) | Returns the minimum-area rotated rectangle enclosing a geometry. The rectangle may be rotated relative to the coordinate axes. Degenerate inputs may result in a Point or LineString being returned. |
 | [ST_PointOnSurface](Geometry-Processing/ST_PointOnSurface.md) | Returns a POINT guaranteed to lie on the surface. |
 | [ST_Polygonize](Geometry-Processing/ST_Polygonize.md) | Generates a GeometryCollection composed of polygons that are formed from the linework of an input GeometryCollection. When the input does not contain any linework that forms a polygon, the function... |
diff --git a/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md b/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
new file mode 100644
index 00000000000..c5e09beb183
--- /dev/null
+++ b/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
@@ -0,0 +1,50 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+ -->
+
+# ST_OffsetCurve
+
+Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
+
+The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
+
+Format: `ST_OffsetCurve(geometry: Geometry, distance: Double, quadrantSegments: Integer)`
+
+Format: `ST_OffsetCurve(geometry: Geometry, distance: Double)`
+
+Return type: `Geometry`
+
+SQL Example
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))
+```
+
+Output: `LINESTRING (0 5, 10 5)`
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))
+```
+
+Output: `LINESTRING (0 -5, 10 -5)`
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))
+```
+
+Output: `LINESTRING (0 5, 10 5)`
diff --git a/docs/api/sql/Geometry-Functions.md b/docs/api/sql/Geometry-Functions.md
index 14ce382530b..d6d6db75757 100644
--- a/docs/api/sql/Geometry-Functions.md
+++ b/docs/api/sql/Geometry-Functions.md
@@ -223,6 +223,7 @@ These functions compute geometric constructions, or alter geometry size or shape
 | [ST_MaximumInscribedCircle](Geometry-Processing/ST_MaximumInscribedCircle.md) | Struct | Finds the largest circle that is contained within a (multi)polygon, or which does not overlap any lines and points. Returns a row with fields: | v1.6.1 |
 | [ST_MinimumBoundingCircle](Geometry-Processing/ST_MinimumBoundingCircle.md) | Geometry | Returns the smallest circle polygon that contains a geometry. The optional quadrantSegments parameter determines how many segments to use per quadrant and the default number of segments has been ch... | v1.0.1 |
 | [ST_MinimumBoundingRadius](Geometry-Processing/ST_MinimumBoundingRadius.md) | Struct | Returns a struct containing the center point and radius of the smallest circle that contains a geometry. | v1.0.1 |
+| [ST_OffsetCurve](Geometry-Processing/ST_OffsetCurve.md) | Geometry | Returns a line at a given offset distance from a linear geometry. Positive distance offsets to the left, negative to the right. | v1.9.0 |
 | [ST_OrientedEnvelope](Geometry-Processing/ST_OrientedEnvelope.md) | Geometry | Returns the minimum-area rotated rectangle enclosing a geometry. The rectangle may be rotated relative to the coordinate axes. Degenerate inputs may result in a Point or LineString being returned. | v1.8.1 |
 | [ST_PointOnSurface](Geometry-Processing/ST_PointOnSurface.md) | Geometry | Returns a POINT guaranteed to lie on the surface. | v1.2.1 |
 | [ST_Polygonize](Geometry-Processing/ST_Polygonize.md) | Geometry | Generates a GeometryCollection composed of polygons that are formed from the linework of an input GeometryCollection. When the input does not contain any linework that forms a polygon, the function... | v1.6.0 |
diff --git a/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md b/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
new file mode 100644
index 00000000000..1802d4a079d
--- /dev/null
+++ b/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
@@ -0,0 +1,54 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+ -->
+
+# ST_OffsetCurve
+
+![ST_OffsetCurve](../../../image/ST_OffsetCurve/ST_OffsetCurve.svg "ST_OffsetCurve")
+
+Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
+
+The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
+
+Format: `ST_OffsetCurve(geometry: Geometry, distance: Double, quadrantSegments: Integer)`
+
+Format: `ST_OffsetCurve(geometry: Geometry, distance: Double)`
+
+Return type: `Geometry`
+
+Since: `v1.9.0`
+
+SQL Example
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))
+```
+
+Output: `LINESTRING (0 5, 10 5)`
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))
+```
+
+Output: `LINESTRING (0 -5, 10 -5)`
+
+```sql
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))
+```
+
+Output: `LINESTRING (0 5, 10 5)`
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
new file mode 100644
index 00000000000..2515275e63a
--- /dev/null
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
@@ -0,0 +1,34 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 300" width="500" height="300" style="background:#ffffff">
+  <defs>
+    <style>
+      text { font-family: 'Segoe UI', Arial, Helvetica, sans-serif; }
+    </style>
+  </defs>
+  <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve</text>
+  <!-- Original line -->
+  <polyline points="80,170 200,170 300,100 420,100" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <text x="250" y="155" text-anchor="middle" font-size="13" font-weight="bold" fill="#4a90d9">Input</text>
+  <!-- Positive offset (left side) -->
+  <polyline points="80,130 200,130 300,60 420,60" fill="none" stroke="#2ecc71" stroke-width="2.5" />
+  <text x="420" y="55" font-size="12" font-weight="bold" fill="#2ecc71">+d (left)</text>
+  <!-- Negative offset (right side) -->
+  <polyline points="80,210 200,210 300,140 420,140" fill="none" stroke="#e67e22" stroke-width="2.5" stroke-dasharray="8,4" />
+  <text x="420" y="155" font-size="12" font-weight="bold" fill="#e67e22">−d (right)</text>
+  <!-- Distance markers -->
+  <line x1="130" y1="130" x2="130" y2="170" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="126" y1="130" x2="134" y2="130" stroke="#999" stroke-width="1" />
+  <line x1="126" y1="170" x2="134" y2="170" stroke="#999" stroke-width="1" />
+  <text x="138" y="154" font-size="12" font-weight="bold" fill="#999">d</text>
+  <line x1="130" y1="170" x2="130" y2="210" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="126" y1="210" x2="134" y2="210" stroke="#999" stroke-width="1" />
+  <text x="138" y="194" font-size="12" font-weight="bold" fill="#999">d</text>
+  <!-- Caption -->
+  <text x="250" y="282" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Returns a line offset by distance d from the input</text>
+  <!-- Legend -->
+  <rect x="63" y="245" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
+  <text x="79" y="256" font-size="13" fill="#333333">Input line</text>
+  <rect x="173" y="245" width="12" height="12" rx="2" fill="#2ecc71" stroke="#2ecc71" stroke-width="1" />
+  <text x="189" y="256" font-size="13" fill="#333333">Positive offset</text>
+  <rect x="313" y="245" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
+  <text x="329" y="256" font-size="13" fill="#333333">Negative offset</text>
+</svg>
diff --git a/flink/src/main/java/org/apache/sedona/flink/Catalog.java b/flink/src/main/java/org/apache/sedona/flink/Catalog.java
index a10d9f15777..3ef00ce247e 100644
--- a/flink/src/main/java/org/apache/sedona/flink/Catalog.java
+++ b/flink/src/main/java/org/apache/sedona/flink/Catalog.java
@@ -70,6 +70,7 @@ public static UserDefinedFunction[] getFuncs() {
       new Functions.ST_BestSRID(),
       new Functions.ST_ClosestPoint(),
       new Functions.ST_ShortestLine(),
+      new Functions.ST_OffsetCurve(),
       new Functions.ST_Centroid(),
       new Functions.ST_Collect(),
       new Functions.ST_CollectionExtract(),
diff --git a/flink/src/main/java/org/apache/sedona/flink/expressions/Functions.java b/flink/src/main/java/org/apache/sedona/flink/expressions/Functions.java
index cf5e5267c78..71029be3a44 100644
--- a/flink/src/main/java/org/apache/sedona/flink/expressions/Functions.java
+++ b/flink/src/main/java/org/apache/sedona/flink/expressions/Functions.java
@@ -309,6 +309,39 @@ public Geometry eval(
     }
   }
 
+  public static class ST_OffsetCurve extends ScalarFunction {
+    @DataTypeHint(
+        value = "RAW",
+        rawSerializer = GeometryTypeSerializer.class,
+        bridgedTo = Geometry.class)
+    public Geometry eval(
+        @DataTypeHint(
+                value = "RAW",
+                rawSerializer = GeometryTypeSerializer.class,
+                bridgedTo = Geometry.class)
+            Object o,
+        @DataTypeHint("Double") Double distance) {
+      Geometry geom = (Geometry) o;
+      return org.apache.sedona.common.Functions.offsetCurve(geom, distance);
+    }
+
+    @DataTypeHint(
+        value = "RAW",
+        rawSerializer = GeometryTypeSerializer.class,
+        bridgedTo = Geometry.class)
+    public Geometry eval(
+        @DataTypeHint(
+                value = "RAW",
+                rawSerializer = GeometryTypeSerializer.class,
+                bridgedTo = Geometry.class)
+            Object o,
+        @DataTypeHint("Double") Double distance,
+        @DataTypeHint("Integer") Integer quadrantSegments) {
+      Geometry geom = (Geometry) o;
+      return org.apache.sedona.common.Functions.offsetCurve(geom, distance, quadrantSegments);
+    }
+  }
+
   public static class ST_Centroid extends ScalarFunction {
     @DataTypeHint(
         value = "RAW",
diff --git a/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java b/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
index f0d7ffa7f14..f5969d59c63 100644
--- a/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
+++ b/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
@@ -251,6 +251,24 @@ public void testShortestLine() {
     assertEquals("LINESTRING (0 0, 3 4)", result.toString());
   }
 
+  @Test
+  public void testOffsetCurve() {
+    Table table =
+        tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
+    table = table.select(call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), 5.0));
+    Geometry result = (Geometry) first(table).getField(0);
+    assertEquals("LINESTRING (0 5, 10 5)", result.toString());
+  }
+
+  @Test
+  public void testOffsetCurveWithQuadrantSegments() {
+    Table table =
+        tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
+    table = table.select(call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), 5.0, 4));
+    Geometry result = (Geometry) first(table).getField(0);
+    assertEquals("LINESTRING (0 5, 10 5)", result.toString());
+  }
+
   @Test
   public void testCentroid() {
     Table polygonTable =
diff --git a/python/sedona/spark/sql/st_functions.py b/python/sedona/spark/sql/st_functions.py
index f32d57e7adc..186aaadd311 100644
--- a/python/sedona/spark/sql/st_functions.py
+++ b/python/sedona/spark/sql/st_functions.py
@@ -1788,6 +1788,32 @@ def ST_OrientedEnvelope(geometry: ColumnOrName) -> Column:
     return _call_st_function("ST_OrientedEnvelope", geometry)
 
 
+@validate_argument_types
+def ST_OffsetCurve(
+    geometry: ColumnOrName,
+    distance: ColumnOrNameOrNumber,
+    quadrant_segments: Optional[Union[ColumnOrName, int]] = None,
+) -> Column:
+    """Return a line at a given offset distance from a linear geometry.
+
+    Positive distance offsets to the left, negative to the right.
+
+    :param geometry: Linear geometry column.
+    :type geometry: ColumnOrName
+    :param distance: Offset distance.
+    :type distance: ColumnOrNameOrNumber
+    :param quadrant_segments: Number of segments to approximate a quarter circle (default 8).
+    :type quadrant_segments: Optional[Union[ColumnOrName, int]]
+    :return: Offset curve as a geometry column.
+    :rtype: Column
+    """
+    if quadrant_segments is None:
+        args = (geometry, distance)
+    else:
+        args = (geometry, distance, quadrant_segments)
+    return _call_st_function("ST_OffsetCurve", args)
+
+
 @validate_argument_types
 def ST_PointN(geometry: ColumnOrName, n: Union[ColumnOrName, int]) -> Column:
     """Get the n-th point (starts at 1) for a geometry.
diff --git a/python/tests/sql/test_dataframe_api.py b/python/tests/sql/test_dataframe_api.py
index 920550a1cfe..9156b1d48f6 100644
--- a/python/tests/sql/test_dataframe_api.py
+++ b/python/tests/sql/test_dataframe_api.py
@@ -907,6 +907,20 @@
         "",
         "POLYGON ((0 0, 4.5 4.5, 5 4, 0.5 -0.5, 0 0))",
     ),
+    (
+        stf.ST_OffsetCurve,
+        ("line", 1.0),
+        "linestring_geom",
+        "ST_AsText(geom)",
+        "LINESTRING (0 1, 5 1)",
+    ),
+    (
+        stf.ST_OffsetCurve,
+        ("line", 1.0, 4),
+        "linestring_geom",
+        "ST_AsText(geom)",
+        "LINESTRING (0 1, 5 1)",
+    ),
     (stf.ST_PointN, ("line", 2), "linestring_geom", "", "POINT (1 0)"),
     (stf.ST_PointOnSurface, ("line",), "linestring_geom", "", "POINT (2 0)"),
     (
@@ -1444,6 +1458,7 @@
     (stf.ST_MinimumBoundingCircle, (None,)),
     (stf.ST_MinimumBoundingRadius, (None,)),
     (stf.ST_OrientedEnvelope, (None,)),
+    (stf.ST_OffsetCurve, (None, 1.0)),
     (stf.ST_Multi, (None,)),
     (stf.ST_Normalize, (None,)),
     (stf.ST_NPoints, (None,)),
diff --git a/python/tests/sql/test_function.py b/python/tests/sql/test_function.py
index 48a24d0ce7a..ff3e1497c4d 100644
--- a/python/tests/sql/test_function.py
+++ b/python/tests/sql/test_function.py
@@ -1983,6 +1983,28 @@ def test_st_shortest_line_empty(self):
         actual = actual_df.take(1)[0][0]
         assert actual is None
 
+    def test_st_offset_curve(self):
+        # Positive distance offsets to the left
+        actual_df = self.spark.sql(
+            "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))"
+        )
+        actual = actual_df.take(1)[0][0]
+        assert actual == "LINESTRING (0 5, 10 5)"
+
+        # Negative distance offsets to the right
+        actual_df = self.spark.sql(
+            "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))"
+        )
+        actual = actual_df.take(1)[0][0]
+        assert actual == "LINESTRING (0 -5, 10 -5)"
+
+        # With quadrantSegments parameter
+        actual_df = self.spark.sql(
+            "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))"
+        )
+        actual = actual_df.take(1)[0][0]
+        assert actual == "LINESTRING (0 5, 10 5)"
+
     def test_st_collect_on_array_type(self):
         # given
         geometry_df = self.spark.createDataFrame(
diff --git a/spark/common/src/main/scala/org/apache/sedona/sql/UDF/Catalog.scala b/spark/common/src/main/scala/org/apache/sedona/sql/UDF/Catalog.scala
index c931694db40..2629d8b178b 100644
--- a/spark/common/src/main/scala/org/apache/sedona/sql/UDF/Catalog.scala
+++ b/spark/common/src/main/scala/org/apache/sedona/sql/UDF/Catalog.scala
@@ -137,6 +137,7 @@ object Catalog extends AbstractCatalog with Logging {
     function[ST_Snap](),
     function[ST_ClosestPoint](),
     function[ST_ShortestLine](),
+    function[ST_OffsetCurve](),
     function[ST_Boundary](),
     function[ST_HasZ](),
     function[ST_HasM](),
diff --git a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Functions.scala b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Functions.scala
index 0925dfb1043..f15efb0e70e 100644
--- a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Functions.scala
+++ b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Functions.scala
@@ -1012,6 +1012,16 @@ private[apache] case class ST_ShortestLine(inputExpressions: Seq[Expression])
   }
 }
 
+private[apache] case class ST_OffsetCurve(inputExpressions: Seq[Expression])
+    extends InferredExpression(
+      inferrableFunction2(Functions.offsetCurve),
+      inferrableFunction3(Functions.offsetCurve)) {
+
+  protected def withNewChildrenInternal(newChildren: IndexedSeq[Expression]) = {
+    copy(inputExpressions = newChildren)
+  }
+}
+
 private[apache] case class ST_IsPolygonCW(inputExpressions: Seq[Expression])
     extends InferredExpression(Functions.isPolygonCW _) {
   protected def withNewChildrenInternal(newChildren: IndexedSeq[Expression]) = {
diff --git a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/st_functions.scala b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/st_functions.scala
index 07f2e78d3bf..f712bf30ffd 100644
--- a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/st_functions.scala
+++ b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/st_functions.scala
@@ -566,6 +566,15 @@ object st_functions {
   def ST_OrientedEnvelope(geometry: String): Column =
     wrapExpression[ST_OrientedEnvelope](geometry)
 
+  def ST_OffsetCurve(geometry: Column, distance: Column): Column =
+    wrapExpression[ST_OffsetCurve](geometry, distance)
+  def ST_OffsetCurve(geometry: String, distance: Double): Column =
+    wrapExpression[ST_OffsetCurve](geometry, distance)
+  def ST_OffsetCurve(geometry: Column, distance: Column, quadrantSegments: Column): Column =
+    wrapExpression[ST_OffsetCurve](geometry, distance, quadrantSegments)
+  def ST_OffsetCurve(geometry: String, distance: Double, quadrantSegments: Int): Column =
+    wrapExpression[ST_OffsetCurve](geometry, distance, quadrantSegments)
+
   def ST_IsPolygonCCW(geometry: Column): Column = wrapExpression[ST_IsPolygonCCW](geometry)
   def ST_IsPolygonCCW(geometry: String): Column = wrapExpression[ST_IsPolygonCCW](geometry)
 
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/PreserveSRIDSuite.scala b/spark/common/src/test/scala/org/apache/sedona/sql/PreserveSRIDSuite.scala
index b9e5b7b29e5..f66794dd53f 100644
--- a/spark/common/src/test/scala/org/apache/sedona/sql/PreserveSRIDSuite.scala
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/PreserveSRIDSuite.scala
@@ -75,6 +75,7 @@ class PreserveSRIDSuite extends TestBaseScala with TableDrivenPropertyChecks {
       ("ST_SetPoint(geom3, 1, ST_Point(0.5, 0.5))", 1000),
       ("ST_ClosestPoint(geom1, geom2)", 1000),
       ("ST_ShortestLine(geom1, geom2)", 1000),
+      ("ST_OffsetCurve(geom3, 1.0)", 1000),
       ("ST_FlipCoordinates(geom1)", 1000),
       ("ST_SubDivide(geom4, 5)", 1000),
       ("ST_Segmentize(geom4, 0.1)", 1000),
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala b/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
index f10f36e38af..1ebccfc16c1 100644
--- a/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
@@ -575,6 +575,22 @@ class dataFrameAPITestScala extends TestBaseScala {
       assertEquals(expected, actual)
     }
 
+    it("Passed ST_OffsetCurve") {
+      val lineDf = sparkSession.sql(
+        "SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
+      val df = lineDf.select(ST_OffsetCurve("geom", 5.0))
+      val actual = df.take(1)(0).get(0).asInstanceOf[Geometry].toText()
+      assertEquals("LINESTRING (0 5, 10 5)", actual)
+    }
+
+    it("Passed ST_OffsetCurve with quadrantSegments") {
+      val lineDf = sparkSession.sql(
+        "SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
+      val df = lineDf.select(ST_OffsetCurve("geom", 5.0, 4))
+      val actual = df.take(1)(0).get(0).asInstanceOf[Geometry].toText()
+      assertEquals("LINESTRING (0 5, 10 5)", actual)
+    }
+
     it("Passed ST_BestSRID") {
       val pointDf = sparkSession.sql("SELECT ST_Point(-177, -60) AS geom")
       val df = pointDf.select(ST_BestSRID("geom").as("geom"))
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala b/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala
index 8d311bae90f..0903a5b818e 100644
--- a/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala
@@ -3047,6 +3047,26 @@ class functionTestScala
     assert(result == null)
   }
 
+  it("should pass ST_OffsetCurve") {
+    // Positive distance offsets to the left
+    var df = sparkSession.sql(
+      "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))")
+    var actual = df.take(1)(0).get(0).asInstanceOf[String]
+    assertEquals("LINESTRING (0 5, 10 5)", actual)
+
+    // Negative distance offsets to the right
+    df = sparkSession.sql(
+      "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))")
+    actual = df.take(1)(0).get(0).asInstanceOf[String]
+    assertEquals("LINESTRING (0 -5, 10 -5)", actual)
+
+    // With quadrantSegments parameter
+    df = sparkSession.sql(
+      "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))")
+    actual = df.take(1)(0).get(0).asInstanceOf[String]
+    assertEquals("LINESTRING (0 5, 10 5)", actual)
+  }
+
   it("Should pass ST_AreaSpheroid") {
     val geomTestCases = Map(
       ("'POINT (-0.56 51.3168)'") -> "0.0",

From 866bd7ca31f450dba44accbf0f6c795e228247b6 Mon Sep 17 00:00:00 2001
From: Jia Yu <jiayu@apache.org>
Date: Tue, 31 Mar 2026 17:54:41 -0700
Subject: [PATCH 2/5] Fix Spotless formatting violations in ST_OffsetCurve
 tests

---
 .../src/test/java/org/apache/sedona/flink/FunctionTest.java | 6 ++----
 .../scala/org/apache/sedona/sql/dataFrameAPITestScala.scala | 6 ++----
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java b/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
index f5969d59c63..b95f45c09e3 100644
--- a/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
+++ b/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
@@ -253,8 +253,7 @@ public void testShortestLine() {
 
   @Test
   public void testOffsetCurve() {
-    Table table =
-        tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
+    Table table = tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
     table = table.select(call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), 5.0));
     Geometry result = (Geometry) first(table).getField(0);
     assertEquals("LINESTRING (0 5, 10 5)", result.toString());
@@ -262,8 +261,7 @@ public void testOffsetCurve() {
 
   @Test
   public void testOffsetCurveWithQuadrantSegments() {
-    Table table =
-        tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
+    Table table = tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
     table = table.select(call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), 5.0, 4));
     Geometry result = (Geometry) first(table).getField(0);
     assertEquals("LINESTRING (0 5, 10 5)", result.toString());
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala b/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
index 1ebccfc16c1..e2e4964d4d7 100644
--- a/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
@@ -576,16 +576,14 @@ class dataFrameAPITestScala extends TestBaseScala {
     }
 
     it("Passed ST_OffsetCurve") {
-      val lineDf = sparkSession.sql(
-        "SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
+      val lineDf = sparkSession.sql("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
       val df = lineDf.select(ST_OffsetCurve("geom", 5.0))
       val actual = df.take(1)(0).get(0).asInstanceOf[Geometry].toText()
       assertEquals("LINESTRING (0 5, 10 5)", actual)
     }
 
     it("Passed ST_OffsetCurve with quadrantSegments") {
-      val lineDf = sparkSession.sql(
-        "SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
+      val lineDf = sparkSession.sql("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
       val df = lineDf.select(ST_OffsetCurve("geom", 5.0, 4))
       val actual = df.take(1)(0).get(0).asInstanceOf[Geometry].toText()
       assertEquals("LINESTRING (0 5, 10 5)", actual)

From fa69154507e3834dc5cc6abb6f6da6c6db4841e9 Mon Sep 17 00:00:00 2001
From: Jia Yu <jiayu@apache.org>
Date: Tue, 31 Mar 2026 18:19:22 -0700
Subject: [PATCH 3/5] Add ST_OffsetCurve to Snowflake UDFs and tests

---
 .../snowflake/snowsql/TestFunctions.java       | 12 ++++++++++++
 .../snowflake/snowsql/TestFunctionsV2.java     | 12 ++++++++++++
 .../apache/sedona/snowflake/snowsql/UDFs.java  | 12 ++++++++++++
 .../sedona/snowflake/snowsql/UDFsV2.java       | 18 ++++++++++++++++++
 4 files changed, 54 insertions(+)

diff --git a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java
index 2c226f70ba0..689c65476fd 100644
--- a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java
+++ b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java
@@ -768,6 +768,18 @@ public void test_ST_NPoints() {
         "select sedona.ST_NPoints(sedona.ST_GeomFromText('LINESTRING(1 2, 3 4, 5 6)'))", 3);
   }
 
+  @Test
+  public void test_ST_OffsetCurve() {
+    registerUDF("ST_OffsetCurve", byte[].class, double.class);
+    verifySqlSingleRes(
+        "select sedona.ST_AsText(sedona.ST_OffsetCurve(sedona.ST_GeomFromText('LINESTRING(0 0, 10 0)'), 5.0))",
+        "LINESTRING (0 5, 10 5)");
+    registerUDF("ST_OffsetCurve", byte[].class, double.class, int.class);
+    verifySqlSingleRes(
+        "select sedona.ST_AsText(sedona.ST_OffsetCurve(sedona.ST_GeomFromText('LINESTRING(0 0, 10 0)'), 5.0, 4))",
+        "LINESTRING (0 5, 10 5)");
+  }
+
   @Test
   public void test_ST_NumGeometries() {
     registerUDF("ST_NumGeometries", byte[].class);
diff --git a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java
index 67bc09b187d..14039081a71 100644
--- a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java
+++ b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java
@@ -716,6 +716,18 @@ public void test_ST_NPoints() {
         "select sedona.ST_NPoints(ST_GeometryFromWKT('LINESTRING(1 2, 3 4, 5 6)'))", 3);
   }
 
+  @Test
+  public void test_ST_OffsetCurve() {
+    registerUDFV2("ST_OffsetCurve", String.class, double.class);
+    verifySqlSingleRes(
+        "select sedona.ST_AsText(sedona.ST_OffsetCurve(ST_GeometryFromWKT('LINESTRING(0 0, 10 0)'), 5.0))",
+        "LINESTRING (0 5, 10 5)");
+    registerUDFV2("ST_OffsetCurve", String.class, double.class, int.class);
+    verifySqlSingleRes(
+        "select sedona.ST_AsText(sedona.ST_OffsetCurve(ST_GeometryFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))",
+        "LINESTRING (0 5, 10 5)");
+  }
+
   @Test
   public void test_ST_NumGeometries() {
     registerUDFV2("ST_NumGeometries", String.class);
diff --git a/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFs.java b/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFs.java
index dafdc8fc974..f78ad7d3f31 100644
--- a/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFs.java
+++ b/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFs.java
@@ -798,6 +798,18 @@ public static byte[] ST_Normalize(byte[] geometry) {
     return GeometrySerde.serialize(Functions.normalize(GeometrySerde.deserialize(geometry)));
   }
 
+  @UDFAnnotations.ParamMeta(argNames = {"geometry", "distance"})
+  public static byte[] ST_OffsetCurve(byte[] geometry, double distance) {
+    return GeometrySerde.serialize(
+        Functions.offsetCurve(GeometrySerde.deserialize(geometry), distance));
+  }
+
+  @UDFAnnotations.ParamMeta(argNames = {"geometry", "distance", "quadrantSegments"})
+  public static byte[] ST_OffsetCurve(byte[] geometry, double distance, int quadrantSegments) {
+    return GeometrySerde.serialize(
+        Functions.offsetCurve(GeometrySerde.deserialize(geometry), distance, quadrantSegments));
+  }
+
   @UDFAnnotations.ParamMeta(argNames = {"geometry"})
   public static int ST_NumGeometries(byte[] geometry) {
     return Functions.numGeometries(GeometrySerde.deserialize(geometry));
diff --git a/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFsV2.java b/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFsV2.java
index 80fbb34d07f..18cf8a281f8 100644
--- a/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFsV2.java
+++ b/snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/UDFsV2.java
@@ -961,6 +961,24 @@ public static String ST_Normalize(String geometry) {
     return GeometrySerde.serGeoJson(Functions.normalize(GeometrySerde.deserGeoJson(geometry)));
   }
 
+  @UDFAnnotations.ParamMeta(
+      argNames = {"geometry", "distance"},
+      argTypes = {"Geometry", "double"},
+      returnTypes = "Geometry")
+  public static String ST_OffsetCurve(String geometry, double distance) {
+    return GeometrySerde.serGeoJson(
+        Functions.offsetCurve(GeometrySerde.deserGeoJson(geometry), distance));
+  }
+
+  @UDFAnnotations.ParamMeta(
+      argNames = {"geometry", "distance", "quadrantSegments"},
+      argTypes = {"Geometry", "double", "int"},
+      returnTypes = "Geometry")
+  public static String ST_OffsetCurve(String geometry, double distance, int quadrantSegments) {
+    return GeometrySerde.serGeoJson(
+        Functions.offsetCurve(GeometrySerde.deserGeoJson(geometry), distance, quadrantSegments));
+  }
+
   @UDFAnnotations.ParamMeta(
       argNames = {"geometry"},
       argTypes = {"Geometry"})

From 5c5d8dd743fffe4e5e740f8bc1aec27188b02835 Mon Sep 17 00:00:00 2001
From: Jia Yu <jiayu@apache.org>
Date: Tue, 31 Mar 2026 21:19:33 -0700
Subject: [PATCH 4/5] Add per-example SVG visuals to ST_OffsetCurve docs

---
 .../Geometry-Processing/ST_OffsetCurve.md     | 26 +++++++---
 .../Geometry-Processing/ST_OffsetCurve.md     | 26 +++++++---
 .../sql/Geometry-Processing/ST_OffsetCurve.md | 24 +++++++---
 docs/image/ST_OffsetCurve/ST_OffsetCurve.svg  | 47 ++++++++++---------
 .../ST_OffsetCurve_negative.svg               | 47 +++++++++++++++++++
 .../ST_OffsetCurve_positive.svg               | 39 +++++++++++++++
 .../ST_OffsetCurve_quadrant.svg               | 42 +++++++++++++++++
 7 files changed, 208 insertions(+), 43 deletions(-)
 create mode 100644 docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg
 create mode 100644 docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg
 create mode 100644 docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg

diff --git a/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md b/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
index e00a0a728b3..300ec32410f 100644
--- a/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
+++ b/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
@@ -19,6 +19,8 @@
 
 # ST_OffsetCurve
 
+![ST_OffsetCurve](../../../image/ST_OffsetCurve/ST_OffsetCurve.svg "ST_OffsetCurve")
+
 Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
 
 The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
@@ -31,22 +33,32 @@ Return type: `Geometry`
 
 Since: `v1.9.0`
 
-SQL Example
+SQL Example:
+
+![ST_OffsetCurve Positive](../../../image/ST_OffsetCurve/ST_OffsetCurve_positive.svg "ST_OffsetCurve Positive Offset")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), 5.0))
 ```
 
-Output: `LINESTRING (0 5, 10 5)`
+Output: `LINESTRING (0 5, 5 5, 5 10)`
+
+SQL Example:
+
+![ST_OffsetCurve Negative](../../../image/ST_OffsetCurve/ST_OffsetCurve_negative.svg "ST_OffsetCurve Negative Offset")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))
+SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0))
 ```
 
-Output: `LINESTRING (0 -5, 10 -5)`
+Output: `11`
+
+SQL Example:
+
+![ST_OffsetCurve QuadrantSegments](../../../image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg "ST_OffsetCurve with quadrantSegments")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))
+SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))
 ```
 
-Output: `LINESTRING (0 5, 10 5)`
+Output: `19`
diff --git a/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md b/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
index c5e09beb183..5853b10a43f 100644
--- a/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
+++ b/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
@@ -19,6 +19,8 @@
 
 # ST_OffsetCurve
 
+![ST_OffsetCurve](../../../../image/ST_OffsetCurve/ST_OffsetCurve.svg "ST_OffsetCurve")
+
 Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
 
 The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
@@ -29,22 +31,32 @@ Format: `ST_OffsetCurve(geometry: Geometry, distance: Double)`
 
 Return type: `Geometry`
 
-SQL Example
+SQL Example:
+
+![ST_OffsetCurve Positive](../../../../image/ST_OffsetCurve/ST_OffsetCurve_positive.svg "ST_OffsetCurve Positive Offset")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), 5.0))
 ```
 
-Output: `LINESTRING (0 5, 10 5)`
+Output: `LINESTRING (0 5, 5 5, 5 10)`
+
+SQL Example:
+
+![ST_OffsetCurve Negative](../../../../image/ST_OffsetCurve/ST_OffsetCurve_negative.svg "ST_OffsetCurve Negative Offset")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))
+SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0))
 ```
 
-Output: `LINESTRING (0 -5, 10 -5)`
+Output: `11`
+
+SQL Example:
+
+![ST_OffsetCurve QuadrantSegments](../../../../image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg "ST_OffsetCurve with quadrantSegments")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))
+SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))
 ```
 
-Output: `LINESTRING (0 5, 10 5)`
+Output: `19`
diff --git a/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md b/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
index 1802d4a079d..300ec32410f 100644
--- a/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
+++ b/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
@@ -33,22 +33,32 @@ Return type: `Geometry`
 
 Since: `v1.9.0`
 
-SQL Example
+SQL Example:
+
+![ST_OffsetCurve Positive](../../../image/ST_OffsetCurve/ST_OffsetCurve_positive.svg "ST_OffsetCurve Positive Offset")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0))
+SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), 5.0))
 ```
 
-Output: `LINESTRING (0 5, 10 5)`
+Output: `LINESTRING (0 5, 5 5, 5 10)`
+
+SQL Example:
+
+![ST_OffsetCurve Negative](../../../image/ST_OffsetCurve/ST_OffsetCurve_negative.svg "ST_OffsetCurve Negative Offset")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), -5.0))
+SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0))
 ```
 
-Output: `LINESTRING (0 -5, 10 -5)`
+Output: `11`
+
+SQL Example:
+
+![ST_OffsetCurve QuadrantSegments](../../../image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg "ST_OffsetCurve with quadrantSegments")
 
 ```sql
-SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))
+SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))
 ```
 
-Output: `LINESTRING (0 5, 10 5)`
+Output: `19`
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
index 2515275e63a..b375b020713 100644
--- a/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
@@ -5,30 +5,33 @@
     </style>
   </defs>
   <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve</text>
-  <!-- Original line -->
-  <polyline points="80,170 200,170 300,100 420,100" fill="none" stroke="#4a90d9" stroke-width="3" />
-  <text x="250" y="155" text-anchor="middle" font-size="13" font-weight="bold" fill="#4a90d9">Input</text>
-  <!-- Positive offset (left side) -->
-  <polyline points="80,130 200,130 300,60 420,60" fill="none" stroke="#2ecc71" stroke-width="2.5" />
-  <text x="420" y="55" font-size="12" font-weight="bold" fill="#2ecc71">+d (left)</text>
-  <!-- Negative offset (right side) -->
-  <polyline points="80,210 200,210 300,140 420,140" fill="none" stroke="#e67e22" stroke-width="2.5" stroke-dasharray="8,4" />
-  <text x="420" y="155" font-size="12" font-weight="bold" fill="#e67e22">−d (right)</text>
+  <!-- Input: L-shaped line -->
+  <polyline points="60,200 280,200 280,60" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <text x="170" y="190" text-anchor="middle" font-size="13" font-weight="bold" fill="#4a90d9">Input</text>
+  <!-- Positive offset (left side) = inner side, clipped corner -->
+  <polyline points="60,160 240,160 240,60" fill="none" stroke="#2ecc71" stroke-width="2.5" />
+  <text x="150" y="152" font-size="12" font-weight="bold" fill="#2ecc71">+d (left)</text>
+  <!-- Negative offset (right side) = outer side, arc at corner -->
+  <polyline points="60,240 280,240 298,239 314,235 326,228 334,218 340,206 340,60"
+    fill="none" stroke="#e67e22" stroke-width="2.5" stroke-dasharray="8,4" />
+  <text x="350" y="248" font-size="12" font-weight="bold" fill="#e67e22">−d (right)</text>
   <!-- Distance markers -->
-  <line x1="130" y1="130" x2="130" y2="170" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
-  <line x1="126" y1="130" x2="134" y2="130" stroke="#999" stroke-width="1" />
-  <line x1="126" y1="170" x2="134" y2="170" stroke="#999" stroke-width="1" />
-  <text x="138" y="154" font-size="12" font-weight="bold" fill="#999">d</text>
-  <line x1="130" y1="170" x2="130" y2="210" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
-  <line x1="126" y1="210" x2="134" y2="210" stroke="#999" stroke-width="1" />
-  <text x="138" y="194" font-size="12" font-weight="bold" fill="#999">d</text>
+  <line x1="130" y1="160" x2="130" y2="200" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="126" y1="160" x2="134" y2="160" stroke="#999" stroke-width="1" />
+  <line x1="126" y1="200" x2="134" y2="200" stroke="#999" stroke-width="1" />
+  <text x="136" y="184" font-size="12" font-weight="bold" fill="#999">d</text>
+  <line x1="130" y1="200" x2="130" y2="240" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="126" y1="240" x2="134" y2="240" stroke="#999" stroke-width="1" />
+  <text x="136" y="224" font-size="12" font-weight="bold" fill="#999">d</text>
+  <!-- Arc label -->
+  <text x="355" y="195" font-size="11" font-style="italic" fill="#e67e22">arc</text>
   <!-- Caption -->
   <text x="250" y="282" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Returns a line offset by distance d from the input</text>
   <!-- Legend -->
-  <rect x="63" y="245" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
-  <text x="79" y="256" font-size="13" fill="#333333">Input line</text>
-  <rect x="173" y="245" width="12" height="12" rx="2" fill="#2ecc71" stroke="#2ecc71" stroke-width="1" />
-  <text x="189" y="256" font-size="13" fill="#333333">Positive offset</text>
-  <rect x="313" y="245" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
-  <text x="329" y="256" font-size="13" fill="#333333">Negative offset</text>
+  <rect x="63" y="250" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
+  <text x="79" y="261" font-size="13" fill="#333333">Input line</text>
+  <rect x="173" y="250" width="12" height="12" rx="2" fill="#2ecc71" stroke="#2ecc71" stroke-width="1" />
+  <text x="189" y="261" font-size="13" fill="#333333">Positive offset</text>
+  <rect x="313" y="250" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
+  <text x="329" y="261" font-size="13" fill="#333333">Negative offset</text>
 </svg>
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg
new file mode 100644
index 00000000000..4093d1b79f0
--- /dev/null
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg
@@ -0,0 +1,47 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 300" width="500" height="300" style="background:#ffffff">
+  <defs>
+    <style>
+      text { font-family: 'Segoe UI', Arial, Helvetica, sans-serif; }
+    </style>
+  </defs>
+  <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve — Negative Offset on L-shape</text>
+  <!-- Geometry range: x[-1,14] y[-4,11]. Canvas: x[40,470] y[35,255]. -->
+  <!-- Scale: xS=430/15≈28.7, yS=220/15≈14.7 -->
+  <!-- Map: cx = (val+1)*28.7+40, cy = 255-(val+4)*14.7 -->
+  <!-- (0,0)→(69,196) (10,0)→(356,196) (10,10)→(356,49) -->
+  <!-- (0,-3)→(69,240) (13,0)→(413,196) (13,10)→(413,49) -->
+  <!-- Arc points at corner (rounded): -->
+  <!-- (10.59,-2.94)→(373,239) (11.15,-2.77)→(389,237) (11.67,-2.49)→(404,233) -->
+  <!-- (12.12,-2.12)→(417,227) (12.49,-1.67)→(427,221) (12.77,-1.15)→(435,213) -->
+  <!-- (12.94,-0.59)→(440,205) -->
+  <!-- Input: LINESTRING(0 0, 10 0, 10 10) -->
+  <polyline points="69,196 356,196 356,49" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <circle cx="69" cy="196" r="4" fill="#4a90d9" />
+  <circle cx="356" cy="196" r="4" fill="#4a90d9" />
+  <circle cx="356" cy="49" r="4" fill="#4a90d9" />
+  <text x="40" y="192" font-size="11" fill="#4a90d9">(0, 0)</text>
+  <text x="320" y="192" font-size="11" fill="#4a90d9">(10, 0)</text>
+  <text x="360" y="47" font-size="11" fill="#4a90d9">(10, 10)</text>
+  <!-- Result: offset curve with arc at outer corner -->
+  <!-- Straight segment: (0,-3)→(10,-3), then arc, then (13,0)→(13,10) -->
+  <polyline points="69,240 356,240 373,239 389,237 404,233 417,227 427,221 435,213 440,205 413,196 413,49"
+    fill="none" stroke="#e67e22" stroke-width="3" stroke-dasharray="8,4" />
+  <circle cx="69" cy="240" r="4" fill="#e67e22" />
+  <circle cx="413" cy="49" r="4" fill="#e67e22" />
+  <text x="40" y="248" font-size="11" fill="#e67e22">(0, -3)</text>
+  <text x="416" y="55" font-size="11" fill="#e67e22">(13, 10)</text>
+  <!-- Distance markers -->
+  <line x1="200" y1="196" x2="200" y2="240" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="196" y1="196" x2="204" y2="196" stroke="#999" stroke-width="1" />
+  <line x1="196" y1="240" x2="204" y2="240" stroke="#999" stroke-width="1" />
+  <text x="207" y="222" font-size="12" font-weight="bold" fill="#999">d</text>
+  <!-- Arc label -->
+  <text x="445" y="230" font-size="11" font-style="italic" fill="#e67e22">arc</text>
+  <!-- Caption -->
+  <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Negative offset creates a smooth arc at the outer corner</text>
+  <!-- Legend -->
+  <rect x="73" y="265" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
+  <text x="89" y="276" font-size="13" fill="#333333">Input line</text>
+  <rect x="253" y="265" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
+  <text x="269" y="276" font-size="13" fill="#333333">Offset curve (distance = -3.0)</text>
+</svg>
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg
new file mode 100644
index 00000000000..393cb2a4efd
--- /dev/null
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg
@@ -0,0 +1,39 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 300" width="500" height="300" style="background:#ffffff">
+  <defs>
+    <style>
+      text { font-family: 'Segoe UI', Arial, Helvetica, sans-serif; }
+    </style>
+  </defs>
+  <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve — Positive Offset on L-shape</text>
+  <!-- Geometry range: x[0,10] y[0,10]. Canvas: x[60,440] y[40,240]. Scale: 38x, 20y (inverted) -->
+  <!-- (0,0)→(60,240) (10,0)→(440,240) (10,10)→(440,40) (5,5)→(250,140) -->
+  <!-- Input: LINESTRING(0 0, 10 0, 10 10) -->
+  <polyline points="60,240 440,240 440,40" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <circle cx="60" cy="240" r="4" fill="#4a90d9" />
+  <circle cx="440" cy="240" r="4" fill="#4a90d9" />
+  <circle cx="440" cy="40" r="4" fill="#4a90d9" />
+  <text x="36" y="245" font-size="11" fill="#4a90d9">(0, 0)</text>
+  <text x="443" y="255" font-size="11" fill="#4a90d9">(10, 0)</text>
+  <text x="443" y="38" font-size="11" fill="#4a90d9">(10, 10)</text>
+  <!-- Result: LINESTRING(0 5, 5 5, 5 10) = positive offset clips inner corner -->
+  <!-- (0,5)→(60,140) (5,5)→(250,140) (5,10)→(250,40) -->
+  <polyline points="60,140 250,140 250,40" fill="none" stroke="#2ecc71" stroke-width="3" />
+  <circle cx="60" cy="140" r="4" fill="#2ecc71" />
+  <circle cx="250" cy="140" r="4" fill="#2ecc71" />
+  <circle cx="250" cy="40" r="4" fill="#2ecc71" />
+  <text x="36" y="135" font-size="11" fill="#2ecc71">(0, 5)</text>
+  <text x="253" y="155" font-size="11" fill="#2ecc71">(5, 5)</text>
+  <text x="218" y="38" font-size="11" fill="#2ecc71">(5, 10)</text>
+  <!-- Distance marker -->
+  <line x1="150" y1="140" x2="150" y2="240" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="146" y1="140" x2="154" y2="140" stroke="#999" stroke-width="1" />
+  <line x1="146" y1="240" x2="154" y2="240" stroke="#999" stroke-width="1" />
+  <text x="156" y="195" font-size="12" font-weight="bold" fill="#999">d = 5</text>
+  <!-- Caption -->
+  <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">LINESTRING (0 5, 5 5, 5 10)</text>
+  <!-- Legend -->
+  <rect x="73" y="265" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
+  <text x="89" y="276" font-size="13" fill="#333333">Input line</text>
+  <rect x="233" y="265" width="12" height="12" rx="2" fill="#2ecc71" stroke="#2ecc71" stroke-width="1" />
+  <text x="249" y="276" font-size="13" fill="#333333">Offset curve (distance = 5.0)</text>
+</svg>
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg
new file mode 100644
index 00000000000..e8703f4caf5
--- /dev/null
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg
@@ -0,0 +1,42 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 300" width="500" height="300" style="background:#ffffff">
+  <defs>
+    <style>
+      text { font-family: 'Segoe UI', Arial, Helvetica, sans-serif; }
+    </style>
+  </defs>
+  <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve — quadrantSegments Effect</text>
+  <!-- Same L-shape with outer offset, comparing default vs qs=16 -->
+  <!-- Using same mapping as negative SVG -->
+  <!-- Input: LINESTRING(0 0, 10 0, 10 10) -->
+  <polyline points="69,196 356,196 356,49" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <circle cx="69" cy="196" r="4" fill="#4a90d9" />
+  <circle cx="356" cy="196" r="4" fill="#4a90d9" />
+  <circle cx="356" cy="49" r="4" fill="#4a90d9" />
+  <text x="40" y="192" font-size="11" fill="#4a90d9">(0, 0)</text>
+  <text x="320" y="192" font-size="11" fill="#4a90d9">(10, 0)</text>
+  <text x="360" y="47" font-size="11" fill="#4a90d9">(10, 10)</text>
+  <!-- Default (qs=8): 9 arc points → coarser arc -->
+  <polyline points="69,240 356,240 373,239 389,237 404,233 417,227 427,221 435,213 440,205 413,196 413,49"
+    fill="none" stroke="#e67e22" stroke-width="2.5" stroke-dasharray="6,4" />
+  <!-- qs=16: 17 arc points → smoother arc (interpolated between the 9 default points) -->
+  <polyline points="69,240 356,240 364,240 373,239 381,238 389,237 397,235 404,233 410,230 417,227 422,224 427,221 431,217 435,213 438,209 440,205 441,200 413,196 413,49"
+    fill="none" stroke="#9b59b6" stroke-width="2.5" />
+  <!-- Zoom circle on the arc corner area -->
+  <circle cx="413" cy="218" r="45" fill="none" stroke="#ccc" stroke-width="1" stroke-dasharray="3,2" />
+  <text x="460" y="218" font-size="11" fill="#999">corner arc</text>
+  <!-- Annotations -->
+  <text x="69" y="254" font-size="11" fill="#e67e22">(0, -3)</text>
+  <text x="416" y="55" font-size="11" fill="#9b59b6">(13, 10)</text>
+  <!-- Point count labels -->
+  <text x="260" y="42" font-size="12" fill="#e67e22">default (8): 11 points</text>
+  <text x="260" y="57" font-size="12" fill="#9b59b6">quadrantSegments=16: 19 points</text>
+  <!-- Caption -->
+  <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Higher quadrantSegments produces smoother arcs at outer corners</text>
+  <!-- Legend -->
+  <rect x="43" y="265" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
+  <text x="59" y="276" font-size="13" fill="#333333">Input</text>
+  <rect x="133" y="265" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
+  <text x="149" y="276" font-size="13" fill="#333333">Default (qs=8)</text>
+  <rect x="293" y="265" width="12" height="12" rx="2" fill="#9b59b6" stroke="#9b59b6" stroke-width="1" />
+  <text x="309" y="276" font-size="13" fill="#333333">Smoother (qs=16)</text>
+</svg>

From 1c527ac229ab0c05526c30b066a25866a7ba432c Mon Sep 17 00:00:00 2001
From: Jia Yu <jiayu@apache.org>
Date: Tue, 31 Mar 2026 21:55:22 -0700
Subject: [PATCH 5/5] Use L-shape geometry in quadrantSegments tests to
 exercise arc behavior

---
 .../apache/sedona/common/FunctionsTest.java   |  14 +--
 .../Geometry-Processing/ST_OffsetCurve.md     |   2 -
 .../Geometry-Processing/ST_OffsetCurve.md     |   2 -
 .../sql/Geometry-Processing/ST_OffsetCurve.md |   2 -
 docs/image/ST_OffsetCurve/ST_OffsetCurve.svg  |  37 ------
 .../ST_OffsetCurve_negative.svg               |  68 ++++++-----
 .../ST_OffsetCurve_positive.svg               |  49 ++++----
 .../ST_OffsetCurve_quadrant.svg               | 107 ++++++++++++------
 .../org/apache/sedona/flink/FunctionTest.java |  19 +++-
 python/tests/sql/test_function.py             |  14 ++-
 .../snowflake/snowsql/TestFunctions.java      |   5 +-
 .../snowflake/snowsql/TestFunctionsV2.java    |   5 +-
 .../sedona/sql/dataFrameAPITestScala.scala    |  11 +-
 .../apache/sedona/sql/functionTestScala.scala |  13 ++-
 14 files changed, 191 insertions(+), 157 deletions(-)
 delete mode 100644 docs/image/ST_OffsetCurve/ST_OffsetCurve.svg

diff --git a/common/src/test/java/org/apache/sedona/common/FunctionsTest.java b/common/src/test/java/org/apache/sedona/common/FunctionsTest.java
index 9264e7ea5ec..92b59489054 100644
--- a/common/src/test/java/org/apache/sedona/common/FunctionsTest.java
+++ b/common/src/test/java/org/apache/sedona/common/FunctionsTest.java
@@ -4287,13 +4287,13 @@ public void offsetCurveEmptyGeometry() throws ParseException {
 
   @Test
   public void offsetCurveWithQuadrantSegments() throws ParseException {
-    // Test with custom quadrant segments
-    Geometry line = Constructors.geomFromWKT("LINESTRING (0 0, 10 0)", 0);
-    Geometry result = Functions.offsetCurve(line, 5.0, 4);
-    assertNotNull(result);
-    // The result should still be a simple offset for a straight line
-    String actual = Functions.asWKT(result);
-    assertEquals("LINESTRING (0 5, 10 5)", actual);
+    // Test with custom quadrant segments on a line with a corner
+    Geometry line = Constructors.geomFromWKT("LINESTRING (0 0, 10 0, 10 10)", 0);
+    Geometry defaultResult = Functions.offsetCurve(line, -3.0);
+    Geometry customResult = Functions.offsetCurve(line, -3.0, 16);
+    assertNotNull(customResult);
+    // Higher quadrantSegments produces more points on the arc at outer corners
+    assertTrue(customResult.getNumPoints() > defaultResult.getNumPoints());
   }
 
   @Test
diff --git a/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md b/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
index 300ec32410f..0e70866f00a 100644
--- a/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
+++ b/docs/api/flink/Geometry-Processing/ST_OffsetCurve.md
@@ -19,8 +19,6 @@
 
 # ST_OffsetCurve
 
-![ST_OffsetCurve](../../../image/ST_OffsetCurve/ST_OffsetCurve.svg "ST_OffsetCurve")
-
 Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
 
 The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
diff --git a/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md b/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
index 5853b10a43f..37ce097cb4f 100644
--- a/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
+++ b/docs/api/snowflake/vector-data/Geometry-Processing/ST_OffsetCurve.md
@@ -19,8 +19,6 @@
 
 # ST_OffsetCurve
 
-![ST_OffsetCurve](../../../../image/ST_OffsetCurve/ST_OffsetCurve.svg "ST_OffsetCurve")
-
 Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
 
 The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
diff --git a/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md b/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
index 300ec32410f..0e70866f00a 100644
--- a/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
+++ b/docs/api/sql/Geometry-Processing/ST_OffsetCurve.md
@@ -19,8 +19,6 @@
 
 # ST_OffsetCurve
 
-![ST_OffsetCurve](../../../image/ST_OffsetCurve/ST_OffsetCurve.svg "ST_OffsetCurve")
-
 Introduction: Returns a line at a given offset distance from a linear geometry. If the distance is positive, the offset is on the left side of the input line; if it is negative, it is on the right side. Returns null for empty geometries.
 
 The optional third parameter `quadrantSegments` controls the number of line segments used to approximate a quarter circle at round joins. The default value is 8.
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
deleted file mode 100644
index b375b020713..00000000000
--- a/docs/image/ST_OffsetCurve/ST_OffsetCurve.svg
+++ /dev/null
@@ -1,37 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 300" width="500" height="300" style="background:#ffffff">
-  <defs>
-    <style>
-      text { font-family: 'Segoe UI', Arial, Helvetica, sans-serif; }
-    </style>
-  </defs>
-  <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve</text>
-  <!-- Input: L-shaped line -->
-  <polyline points="60,200 280,200 280,60" fill="none" stroke="#4a90d9" stroke-width="3" />
-  <text x="170" y="190" text-anchor="middle" font-size="13" font-weight="bold" fill="#4a90d9">Input</text>
-  <!-- Positive offset (left side) = inner side, clipped corner -->
-  <polyline points="60,160 240,160 240,60" fill="none" stroke="#2ecc71" stroke-width="2.5" />
-  <text x="150" y="152" font-size="12" font-weight="bold" fill="#2ecc71">+d (left)</text>
-  <!-- Negative offset (right side) = outer side, arc at corner -->
-  <polyline points="60,240 280,240 298,239 314,235 326,228 334,218 340,206 340,60"
-    fill="none" stroke="#e67e22" stroke-width="2.5" stroke-dasharray="8,4" />
-  <text x="350" y="248" font-size="12" font-weight="bold" fill="#e67e22">−d (right)</text>
-  <!-- Distance markers -->
-  <line x1="130" y1="160" x2="130" y2="200" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
-  <line x1="126" y1="160" x2="134" y2="160" stroke="#999" stroke-width="1" />
-  <line x1="126" y1="200" x2="134" y2="200" stroke="#999" stroke-width="1" />
-  <text x="136" y="184" font-size="12" font-weight="bold" fill="#999">d</text>
-  <line x1="130" y1="200" x2="130" y2="240" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
-  <line x1="126" y1="240" x2="134" y2="240" stroke="#999" stroke-width="1" />
-  <text x="136" y="224" font-size="12" font-weight="bold" fill="#999">d</text>
-  <!-- Arc label -->
-  <text x="355" y="195" font-size="11" font-style="italic" fill="#e67e22">arc</text>
-  <!-- Caption -->
-  <text x="250" y="282" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Returns a line offset by distance d from the input</text>
-  <!-- Legend -->
-  <rect x="63" y="250" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
-  <text x="79" y="261" font-size="13" fill="#333333">Input line</text>
-  <rect x="173" y="250" width="12" height="12" rx="2" fill="#2ecc71" stroke="#2ecc71" stroke-width="1" />
-  <text x="189" y="261" font-size="13" fill="#333333">Positive offset</text>
-  <rect x="313" y="250" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
-  <text x="329" y="261" font-size="13" fill="#333333">Negative offset</text>
-</svg>
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg
index 4093d1b79f0..134472c798b 100644
--- a/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve_negative.svg
@@ -5,40 +5,48 @@
     </style>
   </defs>
   <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve — Negative Offset on L-shape</text>
-  <!-- Geometry range: x[-1,14] y[-4,11]. Canvas: x[40,470] y[35,255]. -->
-  <!-- Scale: xS=430/15≈28.7, yS=220/15≈14.7 -->
-  <!-- Map: cx = (val+1)*28.7+40, cy = 255-(val+4)*14.7 -->
-  <!-- (0,0)→(69,196) (10,0)→(356,196) (10,10)→(356,49) -->
-  <!-- (0,-3)→(69,240) (13,0)→(413,196) (13,10)→(413,49) -->
-  <!-- Arc points at corner (rounded): -->
-  <!-- (10.59,-2.94)→(373,239) (11.15,-2.77)→(389,237) (11.67,-2.49)→(404,233) -->
-  <!-- (12.12,-2.12)→(417,227) (12.49,-1.67)→(427,221) (12.77,-1.15)→(435,213) -->
-  <!-- (12.94,-0.59)→(440,205) -->
+  <!-- Mapping: x range [0,13] → [60,450], y range [-3,10] → [245,35] -->
+  <!-- cx = x*30+60, cy = 245 - (y+3)*16.15 -->
+
   <!-- Input: LINESTRING(0 0, 10 0, 10 10) -->
-  <polyline points="69,196 356,196 356,49" fill="none" stroke="#4a90d9" stroke-width="3" />
-  <circle cx="69" cy="196" r="4" fill="#4a90d9" />
-  <circle cx="356" cy="196" r="4" fill="#4a90d9" />
-  <circle cx="356" cy="49" r="4" fill="#4a90d9" />
+  <polyline points="60,196 360,196 360,35" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <circle cx="60" cy="196" r="4" fill="#4a90d9" />
+  <circle cx="360" cy="196" r="4" fill="#4a90d9" />
+  <circle cx="360" cy="35" r="4" fill="#4a90d9" />
   <text x="40" y="192" font-size="11" fill="#4a90d9">(0, 0)</text>
-  <text x="320" y="192" font-size="11" fill="#4a90d9">(10, 0)</text>
-  <text x="360" y="47" font-size="11" fill="#4a90d9">(10, 10)</text>
-  <!-- Result: offset curve with arc at outer corner -->
-  <!-- Straight segment: (0,-3)→(10,-3), then arc, then (13,0)→(13,10) -->
-  <polyline points="69,240 356,240 373,239 389,237 404,233 417,227 427,221 435,213 440,205 413,196 413,49"
-    fill="none" stroke="#e67e22" stroke-width="3" stroke-dasharray="8,4" />
-  <circle cx="69" cy="240" r="4" fill="#e67e22" />
-  <circle cx="413" cy="49" r="4" fill="#e67e22" />
-  <text x="40" y="248" font-size="11" fill="#e67e22">(0, -3)</text>
-  <text x="416" y="55" font-size="11" fill="#e67e22">(13, 10)</text>
-  <!-- Distance markers -->
-  <line x1="200" y1="196" x2="200" y2="240" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <text x="324" y="192" font-size="11" fill="#4a90d9">(10, 0)</text>
+  <text x="364" y="33" font-size="11" fill="#4a90d9">(10, 10)</text>
+
+  <!-- Result: actual JTS output with 9 arc segments (default qs=8) -->
+  <polyline points="60,245 360,245 377,244 394,240 410,235 424,228 435,219 443,209 448,199 450,196 450,35"
+    fill="none" stroke="#e67e22" stroke-width="3" />
+  <!-- Vertex dots on arc segments -->
+  <circle cx="60" cy="245" r="4" fill="#e67e22" />
+  <circle cx="360" cy="245" r="3" fill="#e67e22" />
+  <circle cx="377" cy="244" r="3" fill="#e67e22" />
+  <circle cx="394" cy="240" r="3" fill="#e67e22" />
+  <circle cx="410" cy="235" r="3" fill="#e67e22" />
+  <circle cx="424" cy="228" r="3" fill="#e67e22" />
+  <circle cx="435" cy="219" r="3" fill="#e67e22" />
+  <circle cx="443" cy="209" r="3" fill="#e67e22" />
+  <circle cx="448" cy="199" r="3" fill="#e67e22" />
+  <circle cx="450" cy="196" r="3" fill="#e67e22" />
+  <circle cx="450" cy="35" r="4" fill="#e67e22" />
+  <text x="40" y="253" font-size="11" fill="#e67e22">(0, -3)</text>
+  <text x="453" y="41" font-size="11" fill="#e67e22">(13, 10)</text>
+
+  <!-- Distance marker -->
+  <line x1="200" y1="196" x2="200" y2="245" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
   <line x1="196" y1="196" x2="204" y2="196" stroke="#999" stroke-width="1" />
-  <line x1="196" y1="240" x2="204" y2="240" stroke="#999" stroke-width="1" />
-  <text x="207" y="222" font-size="12" font-weight="bold" fill="#999">d</text>
-  <!-- Arc label -->
-  <text x="445" y="230" font-size="11" font-style="italic" fill="#e67e22">arc</text>
+  <line x1="196" y1="245" x2="204" y2="245" stroke="#999" stroke-width="1" />
+  <text x="207" y="224" font-size="12" font-weight="bold" fill="#999">d = 3</text>
+
+  <!-- Point count annotation -->
+  <text x="460" y="224" font-size="11" fill="#e67e22">11 points</text>
+  <text x="460" y="237" font-size="11" fill="#e67e22">(9 on arc)</text>
+
   <!-- Caption -->
-  <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Negative offset creates a smooth arc at the outer corner</text>
+  <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Negative offset creates a segmented arc at the outer corner</text>
   <!-- Legend -->
   <rect x="73" y="265" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
   <text x="89" y="276" font-size="13" fill="#333333">Input line</text>
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg
index 393cb2a4efd..a4aa7587542 100644
--- a/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve_positive.svg
@@ -5,30 +5,35 @@
     </style>
   </defs>
   <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve — Positive Offset on L-shape</text>
-  <!-- Geometry range: x[0,10] y[0,10]. Canvas: x[60,440] y[40,240]. Scale: 38x, 20y (inverted) -->
-  <!-- (0,0)→(60,240) (10,0)→(440,240) (10,10)→(440,40) (5,5)→(250,140) -->
+  <!-- Mapping: x range [0,13] → [60,450], y range [-1,10] → [230,35] -->
+  <!-- cx = x*30+60, cy = 230 - y*17.7 -->
+  <!-- (0,0)→(60,230) (10,0)→(360,230) (10,10)→(360,53) -->
+  <!-- (0,5)→(60,141) (5,5)→(210,141) (5,10)→(210,53) -->
+
   <!-- Input: LINESTRING(0 0, 10 0, 10 10) -->
-  <polyline points="60,240 440,240 440,40" fill="none" stroke="#4a90d9" stroke-width="3" />
-  <circle cx="60" cy="240" r="4" fill="#4a90d9" />
-  <circle cx="440" cy="240" r="4" fill="#4a90d9" />
-  <circle cx="440" cy="40" r="4" fill="#4a90d9" />
-  <text x="36" y="245" font-size="11" fill="#4a90d9">(0, 0)</text>
-  <text x="443" y="255" font-size="11" fill="#4a90d9">(10, 0)</text>
-  <text x="443" y="38" font-size="11" fill="#4a90d9">(10, 10)</text>
-  <!-- Result: LINESTRING(0 5, 5 5, 5 10) = positive offset clips inner corner -->
-  <!-- (0,5)→(60,140) (5,5)→(250,140) (5,10)→(250,40) -->
-  <polyline points="60,140 250,140 250,40" fill="none" stroke="#2ecc71" stroke-width="3" />
-  <circle cx="60" cy="140" r="4" fill="#2ecc71" />
-  <circle cx="250" cy="140" r="4" fill="#2ecc71" />
-  <circle cx="250" cy="40" r="4" fill="#2ecc71" />
-  <text x="36" y="135" font-size="11" fill="#2ecc71">(0, 5)</text>
-  <text x="253" y="155" font-size="11" fill="#2ecc71">(5, 5)</text>
-  <text x="218" y="38" font-size="11" fill="#2ecc71">(5, 10)</text>
+  <polyline points="60,230 360,230 360,53" fill="none" stroke="#4a90d9" stroke-width="3" />
+  <circle cx="60" cy="230" r="4" fill="#4a90d9" />
+  <circle cx="360" cy="230" r="4" fill="#4a90d9" />
+  <circle cx="360" cy="53" r="4" fill="#4a90d9" />
+  <text x="36" y="235" font-size="11" fill="#4a90d9">(0, 0)</text>
+  <text x="363" y="245" font-size="11" fill="#4a90d9">(10, 0)</text>
+  <text x="363" y="50" font-size="11" fill="#4a90d9">(10, 10)</text>
+
+  <!-- Result: LINESTRING(0 5, 5 5, 5 10) — inner corner is clipped, no arc -->
+  <polyline points="60,141 210,141 210,53" fill="none" stroke="#2ecc71" stroke-width="3" />
+  <circle cx="60" cy="141" r="4" fill="#2ecc71" />
+  <circle cx="210" cy="141" r="4" fill="#2ecc71" />
+  <circle cx="210" cy="53" r="4" fill="#2ecc71" />
+  <text x="36" y="136" font-size="11" fill="#2ecc71">(0, 5)</text>
+  <text x="213" y="155" font-size="11" fill="#2ecc71">(5, 5)</text>
+  <text x="178" y="50" font-size="11" fill="#2ecc71">(5, 10)</text>
+
   <!-- Distance marker -->
-  <line x1="150" y1="140" x2="150" y2="240" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
-  <line x1="146" y1="140" x2="154" y2="140" stroke="#999" stroke-width="1" />
-  <line x1="146" y1="240" x2="154" y2="240" stroke="#999" stroke-width="1" />
-  <text x="156" y="195" font-size="12" font-weight="bold" fill="#999">d = 5</text>
+  <line x1="150" y1="141" x2="150" y2="230" stroke="#999" stroke-width="1" stroke-dasharray="3,2" />
+  <line x1="146" y1="141" x2="154" y2="141" stroke="#999" stroke-width="1" />
+  <line x1="146" y1="230" x2="154" y2="230" stroke="#999" stroke-width="1" />
+  <text x="156" y="190" font-size="12" font-weight="bold" fill="#999">d = 5</text>
+
   <!-- Caption -->
   <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">LINESTRING (0 5, 5 5, 5 10)</text>
   <!-- Legend -->
diff --git a/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg b/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg
index e8703f4caf5..11c8c7b4781 100644
--- a/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg
+++ b/docs/image/ST_OffsetCurve/ST_OffsetCurve_quadrant.svg
@@ -4,39 +4,80 @@
       text { font-family: 'Segoe UI', Arial, Helvetica, sans-serif; }
     </style>
   </defs>
-  <text x="250" y="22" text-anchor="middle" font-size="16" font-weight="bold" fill="#333333">ST_OffsetCurve — quadrantSegments Effect</text>
-  <!-- Same L-shape with outer offset, comparing default vs qs=16 -->
-  <!-- Using same mapping as negative SVG -->
-  <!-- Input: LINESTRING(0 0, 10 0, 10 10) -->
-  <polyline points="69,196 356,196 356,49" fill="none" stroke="#4a90d9" stroke-width="3" />
-  <circle cx="69" cy="196" r="4" fill="#4a90d9" />
-  <circle cx="356" cy="196" r="4" fill="#4a90d9" />
-  <circle cx="356" cy="49" r="4" fill="#4a90d9" />
-  <text x="40" y="192" font-size="11" fill="#4a90d9">(0, 0)</text>
-  <text x="320" y="192" font-size="11" fill="#4a90d9">(10, 0)</text>
-  <text x="360" y="47" font-size="11" fill="#4a90d9">(10, 10)</text>
-  <!-- Default (qs=8): 9 arc points → coarser arc -->
-  <polyline points="69,240 356,240 373,239 389,237 404,233 417,227 427,221 435,213 440,205 413,196 413,49"
-    fill="none" stroke="#e67e22" stroke-width="2.5" stroke-dasharray="6,4" />
-  <!-- qs=16: 17 arc points → smoother arc (interpolated between the 9 default points) -->
-  <polyline points="69,240 356,240 364,240 373,239 381,238 389,237 397,235 404,233 410,230 417,227 422,224 427,221 431,217 435,213 438,209 440,205 441,200 413,196 413,49"
-    fill="none" stroke="#9b59b6" stroke-width="2.5" />
-  <!-- Zoom circle on the arc corner area -->
-  <circle cx="413" cy="218" r="45" fill="none" stroke="#ccc" stroke-width="1" stroke-dasharray="3,2" />
-  <text x="460" y="218" font-size="11" fill="#999">corner arc</text>
-  <!-- Annotations -->
-  <text x="69" y="254" font-size="11" fill="#e67e22">(0, -3)</text>
-  <text x="416" y="55" font-size="11" fill="#9b59b6">(13, 10)</text>
-  <!-- Point count labels -->
-  <text x="260" y="42" font-size="12" fill="#e67e22">default (8): 11 points</text>
-  <text x="260" y="57" font-size="12" fill="#9b59b6">quadrantSegments=16: 19 points</text>
+  <text x="250" y="18" text-anchor="middle" font-size="15" font-weight="bold" fill="#333333">ST_OffsetCurve — quadrantSegments Effect</text>
+
+  <!-- LEFT CHART: default qs=8 -->
+  <!-- Mapping: x[0,13]→[20,230], y[-3,10]→[230,40] -->
+  <!-- cx = x*16.2+20, cy = 230 - (y+3)*14.6 -->
+  <!-- (0,0)→(20,186) (10,0)→(182,186) (10,10)→(182,40) -->
+  <!-- (0,-3)→(20,230) (13,0)→(231,186) (13,10)→(231,40) -->
+
+  <text x="125" y="36" text-anchor="middle" font-size="13" font-weight="bold" fill="#e67e22">default (qs=8): 11 points</text>
+
+  <!-- Input -->
+  <polyline points="20,186 182,186 182,40" fill="none" stroke="#4a90d9" stroke-width="2" />
+
+  <!-- Default arc: 9 arc points from JTS -->
+  <!-- (10,-3)→(182,230) (10.59,-2.94)→(192,229) (11.15,-2.77)→(201,226) (11.67,-2.49)→(209,222) -->
+  <!-- (12.12,-2.12)→(216,217) (12.49,-1.67)→(222,211) (12.77,-1.15)→(227,203) (12.94,-0.59)→(230,195) (13,0)→(231,186) -->
+  <polyline points="20,230 182,230 192,229 201,226 209,222 216,217 222,211 227,203 230,195 231,186 231,40"
+    fill="none" stroke="#e67e22" stroke-width="2" />
+  <circle cx="182" cy="230" r="2.5" fill="#e67e22" />
+  <circle cx="192" cy="229" r="2.5" fill="#e67e22" />
+  <circle cx="201" cy="226" r="2.5" fill="#e67e22" />
+  <circle cx="209" cy="222" r="2.5" fill="#e67e22" />
+  <circle cx="216" cy="217" r="2.5" fill="#e67e22" />
+  <circle cx="222" cy="211" r="2.5" fill="#e67e22" />
+  <circle cx="227" cy="203" r="2.5" fill="#e67e22" />
+  <circle cx="230" cy="195" r="2.5" fill="#e67e22" />
+  <circle cx="231" cy="186" r="2.5" fill="#e67e22" />
+
+  <!-- Divider -->
+  <line x1="250" y1="30" x2="250" y2="250" stroke="#ddd" stroke-width="1" />
+
+  <!-- RIGHT CHART: qs=16 -->
+  <!-- Mapping: x[0,13]→[270,480], y[-3,10]→[230,40] -->
+  <!-- cx = x*16.2+270, cy = 230 - (y+3)*14.6 -->
+  <!-- (0,0)→(270,186) (10,0)→(432,186) (10,10)→(432,40) -->
+  <!-- (13,0)→(481,186) (13,10)→(481,40) -->
+
+  <text x="375" y="36" text-anchor="middle" font-size="13" font-weight="bold" fill="#9b59b6">qs=16: 19 points</text>
+
+  <!-- Input -->
+  <polyline points="270,186 432,186 432,40" fill="none" stroke="#4a90d9" stroke-width="2" />
+
+  <!-- qs=16 arc: 17 arc points from JTS -->
+  <!-- (10,-3)→(432,230) (10.29,-2.99)→(437,230) (10.59,-2.94)→(442,229) (10.87,-2.87)→(448,228) -->
+  <!-- (11.15,-2.77)→(451,226) (11.41,-2.65)→(455,223) (11.67,-2.49)→(459,222) (11.90,-2.32)→(463,219) -->
+  <!-- (12.12,-2.12)→(466,217) (12.32,-1.90)→(470,214) (12.49,-1.67)→(472,211) (12.65,-1.41)→(475,207) -->
+  <!-- (12.77,-1.15)→(477,203) (12.87,-0.87)→(478,199) (12.94,-0.59)→(480,195) (12.99,-0.29)→(481,190) (13,0)→(481,186) -->
+  <polyline points="270,230 432,230 437,230 442,229 448,228 451,226 455,223 459,222 463,219 466,217 470,214 472,211 475,207 477,203 478,199 480,195 481,190 481,186 481,40"
+    fill="none" stroke="#9b59b6" stroke-width="2" />
+  <circle cx="432" cy="230" r="2" fill="#9b59b6" />
+  <circle cx="437" cy="230" r="2" fill="#9b59b6" />
+  <circle cx="442" cy="229" r="2" fill="#9b59b6" />
+  <circle cx="448" cy="228" r="2" fill="#9b59b6" />
+  <circle cx="451" cy="226" r="2" fill="#9b59b6" />
+  <circle cx="455" cy="223" r="2" fill="#9b59b6" />
+  <circle cx="459" cy="222" r="2" fill="#9b59b6" />
+  <circle cx="463" cy="219" r="2" fill="#9b59b6" />
+  <circle cx="466" cy="217" r="2" fill="#9b59b6" />
+  <circle cx="470" cy="214" r="2" fill="#9b59b6" />
+  <circle cx="472" cy="211" r="2" fill="#9b59b6" />
+  <circle cx="475" cy="207" r="2" fill="#9b59b6" />
+  <circle cx="477" cy="203" r="2" fill="#9b59b6" />
+  <circle cx="478" cy="199" r="2" fill="#9b59b6" />
+  <circle cx="480" cy="195" r="2" fill="#9b59b6" />
+  <circle cx="481" cy="190" r="2" fill="#9b59b6" />
+  <circle cx="481" cy="186" r="2" fill="#9b59b6" />
+
   <!-- Caption -->
-  <text x="250" y="290" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Higher quadrantSegments produces smoother arcs at outer corners</text>
+  <text x="250" y="280" text-anchor="middle" font-size="13" fill="#333333" font-style="italic">Higher quadrantSegments adds more line segments to approximate the arc</text>
   <!-- Legend -->
-  <rect x="43" y="265" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
-  <text x="59" y="276" font-size="13" fill="#333333">Input</text>
-  <rect x="133" y="265" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
-  <text x="149" y="276" font-size="13" fill="#333333">Default (qs=8)</text>
-  <rect x="293" y="265" width="12" height="12" rx="2" fill="#9b59b6" stroke="#9b59b6" stroke-width="1" />
-  <text x="309" y="276" font-size="13" fill="#333333">Smoother (qs=16)</text>
+  <rect x="73" y="258" width="12" height="12" rx="2" fill="#4a90d9" stroke="#4a90d9" stroke-width="1" />
+  <text x="89" y="269" font-size="12" fill="#333333">Input</text>
+  <rect x="163" y="258" width="12" height="12" rx="2" fill="#e67e22" stroke="#e67e22" stroke-width="1" />
+  <text x="179" y="269" font-size="12" fill="#333333">Offset (qs=8)</text>
+  <rect x="293" y="258" width="12" height="12" rx="2" fill="#9b59b6" stroke="#9b59b6" stroke-width="1" />
+  <text x="309" y="269" font-size="12" fill="#333333">Offset (qs=16)</text>
 </svg>
diff --git a/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java b/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
index b95f45c09e3..2171ecc78ea 100644
--- a/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
+++ b/flink/src/test/java/org/apache/sedona/flink/FunctionTest.java
@@ -261,10 +261,21 @@ public void testOffsetCurve() {
 
   @Test
   public void testOffsetCurveWithQuadrantSegments() {
-    Table table = tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom");
-    table = table.select(call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), 5.0, 4));
-    Geometry result = (Geometry) first(table).getField(0);
-    assertEquals("LINESTRING (0 5, 10 5)", result.toString());
+    Table table =
+        tableEnv.sqlQuery("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)') AS geom");
+    Table defaultTable =
+        table.select(
+            call(
+                "ST_NPoints",
+                call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), -3.0)));
+    Table customTable =
+        table.select(
+            call(
+                "ST_NPoints",
+                call(Functions.ST_OffsetCurve.class.getSimpleName(), $("geom"), -3.0, 16)));
+    int defaultPts = (int) first(defaultTable).getField(0);
+    int customPts = (int) first(customTable).getField(0);
+    assertTrue(customPts > defaultPts);
   }
 
   @Test
diff --git a/python/tests/sql/test_function.py b/python/tests/sql/test_function.py
index ff3e1497c4d..ad7cabe7395 100644
--- a/python/tests/sql/test_function.py
+++ b/python/tests/sql/test_function.py
@@ -1998,12 +1998,16 @@ def test_st_offset_curve(self):
         actual = actual_df.take(1)[0][0]
         assert actual == "LINESTRING (0 -5, 10 -5)"
 
-        # With quadrantSegments parameter
-        actual_df = self.spark.sql(
-            "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))"
+        # With quadrantSegments parameter on a line with a corner
+        default_df = self.spark.sql(
+            "SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0))"
         )
-        actual = actual_df.take(1)[0][0]
-        assert actual == "LINESTRING (0 5, 10 5)"
+        default_pts = default_df.take(1)[0][0]
+        custom_df = self.spark.sql(
+            "SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))"
+        )
+        custom_pts = custom_df.take(1)[0][0]
+        assert custom_pts > default_pts
 
     def test_st_collect_on_array_type(self):
         # given
diff --git a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java
index 689c65476fd..0e66423c10c 100644
--- a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java
+++ b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java
@@ -775,9 +775,10 @@ public void test_ST_OffsetCurve() {
         "select sedona.ST_AsText(sedona.ST_OffsetCurve(sedona.ST_GeomFromText('LINESTRING(0 0, 10 0)'), 5.0))",
         "LINESTRING (0 5, 10 5)");
     registerUDF("ST_OffsetCurve", byte[].class, double.class, int.class);
+    registerUDF("ST_NPoints", byte[].class);
     verifySqlSingleRes(
-        "select sedona.ST_AsText(sedona.ST_OffsetCurve(sedona.ST_GeomFromText('LINESTRING(0 0, 10 0)'), 5.0, 4))",
-        "LINESTRING (0 5, 10 5)");
+        "select sedona.ST_NPoints(sedona.ST_OffsetCurve(sedona.ST_GeomFromText('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))",
+        19);
   }
 
   @Test
diff --git a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java
index 14039081a71..df864987fe9 100644
--- a/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java
+++ b/snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java
@@ -723,9 +723,10 @@ public void test_ST_OffsetCurve() {
         "select sedona.ST_AsText(sedona.ST_OffsetCurve(ST_GeometryFromWKT('LINESTRING(0 0, 10 0)'), 5.0))",
         "LINESTRING (0 5, 10 5)");
     registerUDFV2("ST_OffsetCurve", String.class, double.class, int.class);
+    registerUDFV2("ST_NPoints", String.class);
     verifySqlSingleRes(
-        "select sedona.ST_AsText(sedona.ST_OffsetCurve(ST_GeometryFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))",
-        "LINESTRING (0 5, 10 5)");
+        "select sedona.ST_NPoints(sedona.ST_OffsetCurve(ST_GeometryFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))",
+        19);
   }
 
   @Test
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala b/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
index e2e4964d4d7..c14608bc31c 100644
--- a/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/dataFrameAPITestScala.scala
@@ -583,10 +583,13 @@ class dataFrameAPITestScala extends TestBaseScala {
     }
 
     it("Passed ST_OffsetCurve with quadrantSegments") {
-      val lineDf = sparkSession.sql("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0)') AS geom")
-      val df = lineDf.select(ST_OffsetCurve("geom", 5.0, 4))
-      val actual = df.take(1)(0).get(0).asInstanceOf[Geometry].toText()
-      assertEquals("LINESTRING (0 5, 10 5)", actual)
+      val lineDf =
+        sparkSession.sql("SELECT ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)') AS geom")
+      val defaultDf = lineDf.select(ST_NPoints(ST_OffsetCurve("geom", -3.0)))
+      val customDf = lineDf.select(ST_NPoints(ST_OffsetCurve("geom", -3.0, 16)))
+      val defaultPts = defaultDf.take(1)(0).getInt(0)
+      val customPts = customDf.take(1)(0).getInt(0)
+      assertTrue(customPts > defaultPts)
     }
 
     it("Passed ST_BestSRID") {
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala b/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala
index 0903a5b818e..9629cd406ca 100644
--- a/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala
@@ -3060,11 +3060,14 @@ class functionTestScala
     actual = df.take(1)(0).get(0).asInstanceOf[String]
     assertEquals("LINESTRING (0 -5, 10 -5)", actual)
 
-    // With quadrantSegments parameter
-    df = sparkSession.sql(
-      "SELECT ST_AsText(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0)'), 5.0, 4))")
-    actual = df.take(1)(0).get(0).asInstanceOf[String]
-    assertEquals("LINESTRING (0 5, 10 5)", actual)
+    // With quadrantSegments parameter on a line with a corner
+    val defaultDf = sparkSession.sql(
+      "SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0))")
+    val defaultPts = defaultDf.take(1)(0).get(0).asInstanceOf[Int]
+    val customDf = sparkSession.sql(
+      "SELECT ST_NPoints(ST_OffsetCurve(ST_GeomFromWKT('LINESTRING(0 0, 10 0, 10 10)'), -3.0, 16))")
+    val customPts = customDf.take(1)(0).get(0).asInstanceOf[Int]
+    assertTrue(customPts > defaultPts)
   }
 
   it("Should pass ST_AreaSpheroid") {