Audience: But Tethuida, what is displacement mapping?
Tethuida: Well boys and girls...
Quote:
Displacement Mapping is an alternative technique in contrast to bump mapping, normal mapping, and parallax mapping where the actual geometric position of points over the textured surface are displaced along the surface normal according to the values stored into the texture.
For years displacement mapping was a peculiarity of high end rendering systems like renderman, while realtime Application Programming Interfaces, like OpenGL and DirectX, lacked this possibility. One of the reason of this absence is that the original implementation of the displacement mapping required an adaptive tessellation of the surface in order to obtain micropolygons whose size matched the size of a pixel on the screen.
With newest generation of graphics hardware displacement mapping can be interpreted as a kind of vertex-texture mapping, where the values of the texture map do not alter the pixel color, but change the position of the vertex instead. Unlike bump mapping and normal mapping, displacement mapping can in this way produce a genuine rough surface. It is currently only implemented in a few desktop graphics adapters, and it has to be used in conjunction with adaptive tessellation techniques (that increases number of rendered polygons according current viewing settings), to produce highly detailed meshes, and to give a more 3D feel and a greater sense of depth and detail to textures which displacement mapping is applied to.
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