plot_azimuth: Plots an azimuth raster using arrows.
In STARStools: R functions for working spatial/remote sensing data.

Description Usage Arguments Author(s) See Also Examples

Plots an azimuth raster using arrows.

  plot_azimuth(azimuth_raster, basemap_raster,
    magnitude_raster, max_arrows_per_dim = 25,
    arrowfun = arrows, arrow.ex, length = 0.05,
    magnitude_stetch = c(0.2, 0.8),
    azimuth_raster_aggregate_method = "ngb",
    magnitude_raster_aggregate_method, na.rm = TRUE)

`azimuth_raster`	RasterLayer. A raster with azimuth values in units of radians.
`basemap_raster`	RasterLayer. The underlying image (defaults to azimuth_raster).
`magnitude_raster`	RasterLayer. An optional raster which is used to scale the arrow lengths.
`max_arrows_per_dim`	Numeric. The maximum number of arrows to display in the longest dimension.
`arrowfun`	The arrow function to use (see ?arrow.plot).
`arrow.ex`	Numeric. Controls the length of the arrows (see arrow.plot). In general, don't set this as the length will be chosen based on the arrow spacing.
`length`	Numeric. Length of the edges of the arrow head (in inches).
`magnitude_stetch`	Ignore. Not currently working.
`azimuth_raster_aggregate_method`	Character. Function used when resampling the azimuth raster. Defaults to "ngb" (nearest neighbor), but can be "pa" (pixel aggregate).
`magnitude_raster_aggregate_method`	Character. Function used when resampling the magnitude raster. Defaults to "ngb" (nearest neighbor), but can be "pa" (pixel aggregate).
`na.rm`	Logical. Remove NAs when aggregate_method="pa"?

Jonathan A. Greenberg STARStools@estarcion.net

arrow.plot,arrows

tahoe_lidar_bareearth <- raster(system.file("external/tahoe_lidar_bareearth.tif", package="STARStools"))
tahoe_lidar_bareearth_azimuth <- slopeAspect(tahoe_lidar_bareearth,out=c('aspect'),unit='radians')
# Azimuth plot with 25 arrows in the longest direction.
plot_azimuth(azimuth_raster=tahoe_lidar_bareearth_azimuth,basemap_raster=tahoe_lidar_bareearth,magnitude_raster=tahoe_lidar_bareearth,max_arrows_per_dim=25)
# Azimuth plot with 10 arrows in the longest direction.
plot_azimuth(azimuth_raster=tahoe_lidar_bareearth_azimuth,basemap_raster=tahoe_lidar_bareearth,magnitude_raster=tahoe_lidar_bareearth,max_arrows_per_dim=10)