Add multi-observer viewshed and line-of-sight profiles (#1145)

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::