A "windshed" is a raster layer representing upwind or downwind connectivity for a given point. This function computes a range of statistics summarizing a windshed, such as the size, centroid location, and isotropy of the wind accessibility surface. It is useful primarily for comparing the windshed properties of multiple different sites.
Arguments
- x
SpatRaster representing wind accessibility, with higher values indicating greater accessibility. (For example, this could be the output of
random_walk(), orleast_cost(..., rate = TRUE).)- origin
Coordinates of center point (matrix with 2 columns and 1 row).
- radius
Optional windshed radius, in km; cells farther from the origin than this will be excluded from the summary statistics.
Value
A named vector of summary statistics:
centroid_x: Longitude of windshed "centroid". The centroid is the mean of all lon-lat coordinates, weighed by the wind accessibility values inx.centroid_y: Latitude of windshed centroid.centroid_distance: Distance from origin to windshed centroid, in km.centroid_bearing: Bearing from origin to windshed centroid, in degrees.windshed_distance: Mean distance from origin, in km. This is the average distance from the origin to every grid cell, weighted by accessibility.windshed_bearing: Mean bearing from origin, in degrees. This is the circular-mean bearing from the origin to every other grid cell, weighted by accessibility.windshed_isotropy: Circular standard deviation of the bearing from the origin to every other grid cell, weighted by accessibility. Low values indicate that accessible sites are concentrated in a narrow range of compass directions, while high values indicate a wide distribution of directions. The range of possible values is 0-1.windshed_size: Mean accessibility. This is the average of all accessibility values, weighted to correct for grid distortions. Higher values indicate landscapes with greater overall wind accessibility.windshed_landarea: A relative measure of the land area covered by grid cells with nonzero wind accessibility.