SoBumpMap(3) on Linux
The text 987c81d5827e, as Debian 8 (Jessie) shipped it.
The SoBumpMap class is used to map a bump map onto subsequent shapes. SoBumpMap has support for two types of maps. If the image is a three component (RGB) image, it will be treated as a normal map, where the red image component equals the X normal component, green equals Y, and blue is Z. See http://www.paulsprojects.net/tutorials/simplebump/simplebump.html for a nice introduction about bump mapping and normal maps.