Merge pull request #6 from dbech/t3code/7d116f6f

Add Fresnel zone overlays

Author: dbech

electron/raster/gdal-loader.ts

@@ -22,6 +22,16 @@ type Stats = {
   std_dev?: number;
 };
 
+type GdalUnitInfo = {
+  units?: string;
+  value?: number;
+};
+
+type SpatialReferenceWithUnits = SpatialReference & {
+  getAngularUnits?: () => GdalUnitInfo;
+  getLinearUnits?: () => GdalUnitInfo;
+};
+
 export async function loadDsmProject(
   paths: string[],
 ): Promise<DsmProjectSummary> {
@@ -76,6 +86,9 @@ export async function loadDsmProject(
       projection,
     );
     const firstNoData = openedFiles[0]!.nodata;
+    const distanceUnit = distanceUnitForSrs(firstSrs);
+    const elevationUnit = firstFile.band.unitType || "unknown";
+    const elevationMetersPerUnit = metersPerElevationUnit(elevationUnit);
 
     const summary: DsmProjectSummary = {
       id: projectId,
@@ -91,10 +104,12 @@ export async function loadDsmProject(
       ),
       crsWkt: firstSrs?.toWKT() ?? "",
       epsg,
+      distance: distanceUnit,
       extent: projectExtent,
       pixelSize: firstFile.pixelSize,
       elevation: {
-        unit: firstFile.band.unitType || "unknown",
+        unit: elevationUnit,
+        metersPerUnit: elevationMetersPerUnit,
         min: projectMin,
         max: projectMax,
         ...(firstNoData === undefined ? {} : { nodata: firstNoData }),
@@ -208,6 +223,8 @@ function warningsForProject(
   sourceSrs: SpatialReference | null,
 ): string[] {
   const warnings: string[] = [];
+  const horizontalUnit = distanceUnitForSrs(sourceSrs);
+  const elevationUnit = files[0]?.band.unitType || "unknown";
 
   if (!sourceSrs) {
     warnings.push(
@@ -219,6 +236,18 @@ function warningsForProject(
     );
   }
 
+  if (horizontalUnit.metersPerUnit === null) {
+    warnings.push(
+      "Fresnel zones are hidden because the DSM horizontal unit cannot be converted to metres.",
+    );
+  }
+
+  if (metersPerElevationUnit(elevationUnit) === null) {
+    warnings.push(
+      "Fresnel zones are hidden because the DSM elevation unit cannot be converted to metres.",
+    );
+  }
+
   for (let i = 0; i < files.length; i++) {
     for (let j = i + 1; j < files.length; j++) {
       if (extentsOverlap(files[i]!.extent, files[j]!.extent)) {
@@ -239,6 +268,57 @@ function warningsForProject(
   return warnings;
 }
 
+function distanceUnitForSrs(sourceSrs: SpatialReference | null): {
+  unit: string;
+  metersPerUnit: number | null;
+} {
+  if (!sourceSrs) return { unit: "unknown", metersPerUnit: null };
+
+  const srsWithUnits = sourceSrs as SpatialReferenceWithUnits;
+  const unitInfo = sourceSrs.isGeographic()
+    ? srsWithUnits.getAngularUnits?.()
+    : srsWithUnits.getLinearUnits?.();
+  const unit = unitInfo?.units || "unknown";
+  const metersPerUnit = sourceSrs.isGeographic()
+    ? null
+    : finitePositiveOrNull(unitInfo?.value);
+
+  return { unit, metersPerUnit };
+}
+
+function metersPerElevationUnit(unit: string): number | null {
+  const normalized = unit.trim().toLowerCase();
+  if (normalized === "" || normalized === "unknown") return null;
+
+  if (["m", "meter", "meters", "metre", "metres"].includes(normalized)) {
+    return 1;
+  }
+
+  if (
+    [
+      "ft",
+      "foot",
+      "feet",
+      "international foot",
+      "international feet",
+      "us survey foot",
+      "us survey feet",
+      "survey foot",
+      "survey feet",
+    ].includes(normalized)
+  ) {
+    return 0.3048;
+  }
+
+  return null;
+}
+
+function finitePositiveOrNull(value: number | undefined): number | null {
+  return typeof value === "number" && Number.isFinite(value) && value > 0
+    ? value
+    : null;
+}
+
 function rasterStats(band: RasterBand): Stats {
   try {
     const stats = band.computeStatistics(true) as Stats;

electron/raster/project-registry.test.ts

@@ -36,7 +36,8 @@ function testProject(id: string, close: () => void): DsmProject {
     sourceSrs: null,
     summary: {
       crsWkt: "",
-      elevation: { min: 0, max: 1, unit: "unknown" },
+      distance: { metersPerUnit: null, unit: "unknown" },
+      elevation: { metersPerUnit: null, min: 0, max: 1, unit: "unknown" },
       extent: {
         minX: 0,
         minY: 0,

package.json

@@ -1,6 +1,6 @@
 {
   "name": "path-profile",
-  "version": "0.1.3",
+  "version": "0.1.4",
   "private": true,
   "type": "module",
   "main": "dist-electron/main.cjs",

src/components/path-profile-app.tsx

@@ -28,6 +28,7 @@ import { getPathProfileApi, hasDesktopBridge } from "~/lib/electron-api";
 import { exportProfileStatus } from "~/lib/export-profile-status";
 import {
   createDefaultLineOfSightEndpoints,
+  type FresnelZoneUnitScales,
   type LineOfSightEndpointId,
   type LineOfSightEndpoints,
 } from "~/lib/line-of-sight";
@@ -194,6 +195,19 @@ export function PathProfileApp() {
     project?.elevation.unit && project.elevation.unit !== "unknown"
       ? project.elevation.unit
       : null;
+  const fresnelUnitScales = useMemo<FresnelZoneUnitScales | null>(() => {
+    const horizontalMetersPerUnit = project?.distance.metersPerUnit;
+    const verticalMetersPerUnit = project?.elevation.metersPerUnit;
+
+    if (
+      !isPositiveFinite(horizontalMetersPerUnit) ||
+      !isPositiveFinite(verticalMetersPerUnit)
+    ) {
+      return null;
+    }
+
+    return { horizontalMetersPerUnit, verticalMetersPerUnit };
+  }, [project]);
 
   const noticeMessages = useMemo(
     () => (project ? warnings : ["Open a DEM from File > Open DEM..."]),
@@ -1022,6 +1036,7 @@ export function PathProfileApp() {
         <div className="min-h-0 flex-1 px-4">
           <ProfileChart
             elevationUnit={elevationUnit}
+            fresnelUnitScales={fresnelUnitScales}
             lineOfSightEndpoints={lineOfSightEndpoints}
             lineOfSightDrafts={lineOfSightDrafts}
             points={profilePoints}
@@ -1211,6 +1226,10 @@ function errorMessage(error: unknown): string {
   return error instanceof Error ? error.message : String(error);
 }
 
+function isPositiveFinite(value: number | null | undefined): value is number {
+  return typeof value === "number" && Number.isFinite(value) && value > 0;
+}
+
 function themeLabel(theme: ThemeMode): string {
   switch (theme) {
     case "system":