GDAL does has hillshading routines (gdaldem hillshade), but it does not have the raytracing, spherical UV shading, or ambient occlusion layers included in raysh

GDAL does has hillshading routines (gdaldem hillshade), but it does not have the raytracing, spherical UV shading, or ambient occlusion layers included in rayshader. It's hillshading routine is basically the rayshader's lamb_shade function--functional, but not going to win any beauty contests. GRASS does have a raytracing option, but if you look up the images produced by it--they aren't pretty. Much more of a functional API to see where actual shadows are falling, and not at all something to produce nice looking maps. The real killer feature in rayshader is the seamless API for combining all of these layers. Being able to adjust the intensity of each layer individual, add water, change color and texture programmatically--no other software focuses nearly as much on the aesthetics of a great looking map. I haven't found anything other than actual 3D modeling software that can produce similar-style hillshades--combining texturing, raytracing, local shadows, and ambient occlusion. What's great (in my highly biased opinion!) about this package is the ability to go programmatically straight from the DEM to a hillshade, without having to save the data and load it into Blender or something similar.