What are image maps?
An image map (sometimes called texture map) is a regular picture file in an image format such as jpeg, bmp, tiff, or png. Image maps are used in materials to create
specific effects or patterns.
They are known by various names depending on the parameters they are used for:
- Color maps replace a solid color with an image that repeats across a surface; for example, cloth or wood patterns.
- Highlight maps (or specular maps) create the appearance of relief. Specular maps work best to create visible noise that in the real world
if touched would feel smooth; for example, metallic paint.
- Reflection maps provide an image that is reflected off shiny objects. The default in Hardware rendering is to use the environment’s reflection
map, so that the object reflects the environment.
Note
Reflection maps have no effect in Ray Tracing. The reflections in Ray Tracing will accurately reflect the environment and
other objects in the scene. A large visual difference will be seen between Hardware rendering and Ray Tracing if a reflection
map is used.
- Transparency maps determine which parts of an object are opaque and which parts are transparent. They can be used for materials with holes
punched out such as a metal grill or perforated rubber. Darker areas of the transparency map produce an opaque material, while
brighter areas create a more transparent appearance.
Often a transparency map is the inverse of a color map. If the color map image format has an alpha channel, you can use that
alpha as the transparency map.
- Bump maps break up the relief of a surface. In the real world, if the surface were touched it would feel bumpy; for example, tire treads
or rough plastic.
Bump textures must be normal maps (that is, they must contain elevation as well as vector information).
- Decal maps define the shape and transparency of a decal material. This is similar to a transparency map, except that decals can be layered
on top of other materials; for example, the numbers on a keypad or a painted logo.
