Normalmap

Normalmap for a bowl model

Heightmap for parallax mapping

Normal maps are images that store per-pixel surface normals directly in the RGB values of an image. Properly done normalmaps can dramatically increase object detalisation without adding more polygons.

Therefore, normalmaps have a bunch fo limits and quirks:

• Tangentspace normalmap is based on vertex normals, if vertex normals is adjusted, normalmap is outdated.
• There is DirectX and OpenGL normalmap format, should figure out what format tool is producing and fix normalmap if it doesnt fit.
• UV seams and 'hard edges' produces by vertex normals is tricky.
• Normalmappers have a couple of quirks (aliasing, noise).

Recommended articles on normalmaps:

• Polycount Wiki
• Normalmaps for the Technical Game Modeler

In Darkplaces Engine, normalmaps are:

• Tangent-space RGB
• OpenGL-oriented (X stores horizontal, Y vertical)
• Optionally can store alpha component which represents height that will be use for parallax mapping.
• Compressed to DXT1 (if not alpha) or DXT5

See also

• Texture