Add visibility module to exports, accessor, docs, and README (#1145)

Author: brendancol

README.md

@@ -316,6 +316,9 @@ Same-CRS tiles skip reprojection entirely and are placed by direct coordinate al
 | [TRI](xrspatial/terrain_metrics.py) | Computes Terrain Ruggedness Index (local elevation variation) | Riley et al. 1999 | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Landforms](xrspatial/terrain_metrics.py) | Classifies terrain into 10 landform types using the Weiss (2001) TPI scheme | Weiss 2001 | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Viewshed](xrspatial/viewshed.py) | Determines visible cells from a given observer point on terrain | GRASS GIS r.viewshed | ✅️ | ✅️ | 🔄 | 🔄 |
+| [Cumulative Viewshed](xrspatial/visibility.py) | Counts how many observers can see each cell | Custom | ✅️ | 🔄 | 🔄 | 🔄 |
+| [Visibility Frequency](xrspatial/visibility.py) | Fraction of observers with line-of-sight to each cell | Custom | ✅️ | 🔄 | 🔄 | 🔄 |
+| [Line of Sight](xrspatial/visibility.py) | Elevation profile and visibility along a point-to-point transect | Custom | ✅️ | 🔄 | 🔄 | 🔄 |
 | [Min Observable Height](xrspatial/experimental/min_observable_height.py) | Finds the minimum observer height needed to see each cell *(experimental)* | Custom | ✅️ | | | |
 | [Perlin Noise](xrspatial/perlin.py) | Generates smooth continuous random noise for procedural textures | Perlin 1985 | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Worley Noise](xrspatial/worley.py) | Generates cellular (Voronoi) noise returning distance to the nearest feature point | Worley 1996 | ✅️ | ✅️ | ✅️ | ✅️ |

docs/source/reference/surface.rst

@@ -81,6 +81,27 @@ Viewshed
 
     xrspatial.viewshed.viewshed
 
+Cumulative Viewshed
+===================
+.. autosummary::
+    :toctree: _autosummary
+
+    xrspatial.visibility.cumulative_viewshed
+
+Visibility Frequency
+====================
+.. autosummary::
+    :toctree: _autosummary
+
+    xrspatial.visibility.visibility_frequency
+
+Line of Sight
+=============
+.. autosummary::
+    :toctree: _autosummary
+
+    xrspatial.visibility.line_of_sight
+
 Perlin Noise
 ============
 .. autosummary::

xrspatial/__init__.py

@@ -119,6 +119,9 @@
 from xrspatial.hydro import twi_d8  # noqa
 from xrspatial.polygonize import polygonize  # noqa
 from xrspatial.viewshed import viewshed  # noqa
+from xrspatial.visibility import cumulative_viewshed  # noqa
+from xrspatial.visibility import line_of_sight  # noqa
+from xrspatial.visibility import visibility_frequency  # noqa
 from xrspatial.hydro import basin  # noqa: unified wrapper
 from xrspatial.hydro import basin_d8  # noqa
 from xrspatial.hydro import basins  # noqa: backward-compat alias

xrspatial/accessor.py

@@ -212,6 +212,18 @@ def viewshed(self, x, y, **kwargs):
         from .viewshed import viewshed
         return viewshed(self._obj, x, y, **kwargs)
 
+    def cumulative_viewshed(self, observers, **kwargs):
+        from .visibility import cumulative_viewshed
+        return cumulative_viewshed(self._obj, observers, **kwargs)
+
+    def visibility_frequency(self, observers, **kwargs):
+        from .visibility import visibility_frequency
+        return visibility_frequency(self._obj, observers, **kwargs)
+
+    def line_of_sight(self, x0, y0, x1, y1, **kwargs):
+        from .visibility import line_of_sight
+        return line_of_sight(self._obj, x0, y0, x1, y1, **kwargs)
+
     def min_observable_height(self, x, y, **kwargs):
         from .experimental.min_observable_height import min_observable_height
         return min_observable_height(self._obj, x, y, **kwargs)