Texturing a Pre-modelled Environment

Texturing refers to the use of additives in paint to give depth and texture to the surface being painted. (Gillette, 1999) This essay discusses the difference between 2d and 3d texture mapping techniques, including the way they are mapped. When looking at 2d mapping, one has to take into consideration the coordinates in the U (horizontal) and V (vertical) axis which go from 0 to 1. A texture map is applied using the coordinate system to match each 3D point on the surface to a 2D point on a texture (any regular image). This is called UV mapping, because the 2D surface consists of a U and V axis.

While 2d texture mapping consists of a flat 2d bitmap image on a flat or curved 3d surface, 3d texture mapping computes the texture color by mapping the object's 3d location in a space directly into a color using small C language procedural texture functions. 3D textures may also be locally and globally transformed just as with cameras and basic geometry.

The three methods of mapping 3d objects are:
1. Automatic mapping
This method yields the fastest mapping results and is used before any other mapping tool, because it maps the whole scene regardless of any mapping procedures already performed.

2. Unwrapping
Is fast yet has high quality mapping of complex shapes

3 Unwrapping using the Interactive Mapper
Has the highest quality results for planar, spherical, polar, and cylindrical shapes, mapping different parts of the models separately available in real time interactive mapping environment.

There are bump map textures that change the way light interacts with the applied surface, these come in two types, grayscale and RGB (Red, green and blue). Bump maps change the depth of the rendered pixels and are only available in 3d viewpoint. On the other hand height maps are useful for rivets, screws, gashes and stuff that is not complex. Normal maps are RGB images, depicting where change in the angle of rendered pixel occurs. This is useful for rendering folds, wrinkles and complex surfaces like the face and body.

Different implementations of 2D texture mapping often can be distinguished from the method used to filter the texture. Since a 2D texture image must be shrunk or enlarged to match the dimensions of its projected area on a textured object, texture filtering is required so that no unusual artifacts are introduced into the final image.


Reference:
Gillette, M. J. Theatrical Design and Production: An Introduction to Scene Design and Construction, Lighting, Sound, Costume, and Makeup. 1999. Forth Edition. McGraw Hill.

https://www.okino.com/new/toolkit/1-11.htm

http://www.righthemisphere.com/support/tutorials/duv/User_Reference_for_Deep_UV.pdf