Repository and download: github.com/zoran-cuckovic/QGIS-terrain-shading
The algorithm for relief shading is available in the official QGIS plugin repository and can be installed as usual (In QGIS go to Plugins -> Manage and install … ). Be sure to enable experimental plugins.
The tool will be available in the top level of the QGIS processing toolbox as a separate provider.
If the standard installation does not work, the plugin can be downloaded for the repository (above) and installed manually: First you need to locate your QGIS plugins folder. On Windows it would be ‘C:\users\username\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins’ (or just do a file search for ‘QGIS3’ …)
Plugin code can then be extracted in a new folder inside the plugins folder (you should name the folder TerrainShading). Take care that the code is not inside a subfolder - the folder structure should be like this:
QGIS3\profiles\default\python\plugins\
[some QGIS plugin folders…]
TerrainShading
dem_shading.py
metadata.txt
[other files and folders…]
Finally, there is a version made as QGIS script, which can be downloaded from the script branch and installed as a QGIS script.
See at LandscapeArchaeology.org/qgis-terrain-shading.
To test the algorithm output, you can find a series of models in the Test branch of this repository (test-data).