plug-ins from the registry
CFLAGS="-O2 -DG_DISABLE_ASSERT -DENABLE_NLS" gimptool --install l2height-0.7.c
<Image>/Filters/Map/Light to Height
I didn't do much to the plug-in options, I just changed the height some.
The resulting image was unintentionally beautiful, I thought:
GIMP/registry/l2height GIMP