A Comparator for Rays which compares them by their theta angle.
A Comparator for Rays which compares them by their theta angle. This is used in the binary search that is performed in thetaToAlpha.
Compute the viewshed of the tile using the R2 algorithm.
Compute the viewshed of the tile using the R2 algorithm. Makes use of the compute method of this object.
Elevations in units of meters
The x position of the vantage point
The y position of the vantage point
The aggregation operator to use (e.g. Or)
Compute the viewshed of the elevatonTile using the R2 algorithm from [1].
Compute the viewshed of the elevatonTile using the R2 algorithm from [1]. The numbers in the elevationTile are assumed to be elevations in units of meters. The results are written into the viewshedTile.
1. Franklin, Wm Randolph, and Clark Ray. "Higher isn’t necessarily better: Visibility algorithms and experiments." Advances in GIS research: sixth international symposium on spatial data handling. Vol. 2. Taylor & Francis Edinburgh, 1994.
Elevations in units of meters
The tile into which the viewshed will be written
The x position of the vantage point
The y position of the vantage point
The absolute height (above sea level) of the vantage point
The direction from which the rays are allowed to come
Rays shining in from other tiles
A callback to communicate rays which have reached the periphery of the tile
The resolution of the elevationTile in units of meters/pixel
The maximum distance that any ray is allowed to travel
Whether to account for the Earth's curvature or not
The aggregation operator to use
The absolute altitude (above sea level) to query; if -∞, use the terrain height
The direction (in radians) of the camera
The camera field of view, rays whose dot product with the camera direction are less than this are filtered out
Any ray within this many radians of vertical (horizontal) will be considered vertical (horizontal)
Generate an empty viewshed tile.
Generate an empty viewshed tile.
The number of columns
The number of rows
An implementation of the R2 [1] Viewshed algorithm.
1. Franklin, Wm Randolph, and Clark Ray. "Higher isn’t necessarily better: Visibility algorithms and experiments." Advances in GIS research: sixth international symposium on spatial data handling. Vol. 2. Taylor & Francis Edinburgh, 1994.