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Texture mapping

By default, a 3d model has the appearance of a clay, or plastic object when it is rendered (see rendering). In order to make a model appear realistic, all of the material properties of objects we are used to seeing in the real world must be painted into the surface of a model.

To paint these textures on a model, A square image file must be "shrink wrapped" on the surface around the entirety of the model. The problem with this is that if you simply project a map on the surface, you can imagine that the view you project from will stretch across the surface from any other angle the model is viewed at. To compensate for this, special coordinates can be manipulated on the model's geometry to "unwrap" the shape to be easier painted. These coordinates are called UV mapping. You can imagine UV mapping as taking the peel off of an orange and laying it out flat. Once the UV coordinates are created, a seemless texture can be painted onto the surface using image files.

To simulate the material properties of a surface type (metal, stone, wood, etc.) Special care must be given to making the texture maps have the right Values and properties for the given material. For example, in the 3d realm, there is no difference between a block of wood and a block of stone as far as the computer is concerned. These different properties must be carefully created.

Texture maps are assigned to different channels in a Shader (or material). For example, you would have texture maps coresponding to The color channel, The specular color (how much light is reflected back to the camera), and perhaps surface bumpiness and transperency depending on the model.