Editing Normal mapping (section)

== History ==
In 1978 [[Jim Blinn]] described how the normals of a surface could be perturbed to make geometrically flat faces have a detailed appearance.<ref>Blinn. ''[https://www.microsoft.com/en-us/research/wp-content/uploads/1978/01/p286-blinn.pdf Simulation of Wrinkled Surfaces]'', Siggraph 1978</ref>
The idea of taking geometric details from a high polygon model was introduced in "Fitting Smooth Surfaces to Dense Polygon Meshes" by Krishnamurthy and Levoy, Proc. [[SIGGRAPH]] 1996,<ref>Krishnamurthy and Levoy, ''[http://www.graphics.stanford.edu/papers/surfacefitting/ Fitting Smooth Surfaces to Dense Polygon Meshes]'', SIGGRAPH 1996</ref> where this approach was used for creating [[displacement mapping|displacement maps]] over [[nurbs]]. In 1998, two papers were presented with key ideas for transferring details with normal maps from high to low polygon meshes: "Appearance Preserving Simplification", by Cohen et al. SIGGRAPH 1998,<ref>Cohen et al., [http://www.cs.unc.edu/~geom/APS/APS.pdf Appearance-Preserving Simplification], SIGGRAPH 1998 '''(PDF)'''</ref> and  "A general method for preserving attribute values on simplified meshes" by Cignoni et al. IEEE Visualization '98.<ref>Cignoni et al., [http://vcg.isti.cnr.it/publications/papers/rocchini.pdf A general method for preserving attribute values on simplified meshes], IEEE Visualization 1998 '''(PDF)'''</ref> The former introduced the idea of storing surface normals directly in a texture, rather than displacements, though it required the low-detail model to be generated by a particular constrained simplification algorithm. The latter presented a simpler approach that decouples the high and low polygonal mesh and allows the recreation of any attributes of the high-detail model (color, [[texture mapping|texture coordinates]], [[displacement mapping|displacements]], etc.) in a way that is not dependent on how the low-detail model was created. The combination of storing normals in a texture, with the more general creation process is still used by most currently available tools.