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Modern engines use up to 5 different textures for one single texture ingame. Those 5 types are explained here!

In almost all cases, you start making a new texture with the diffuse-map. Diffuse-maps are still almost always created manually in an image processing program, e.g. hand-painted or delivered from a photograph, similar to the way “old-style” textures were made in the past. The diffuse-map shows material color when the surface is diffusely lit. Thus, you should not draw any hard shadows into the diffuse lit - they are automatically created by the engine later (if a normal map is used too). You should however, in some cases, draw some soft shadow into the diffuse map, a sort of “rechability factor” (“How hard is it for the light to reach a certain spot on the texture?”). This implies that a diffuse-map of, for example, a corrugated metal or a rough rock surface could be an image that only has a single shade of grey! Also note that the end lit material tends to look best when you use pixel values of medium brightness. Moreover, high-contrast and high-frequency components should be used with care in diffuse-maps, as such components often interfere with normal-maps later, compromizing the effect of dynamic lightning. Also the specular highlights might look strange with such diffuse-maps.

Specular-maps (sometimes also called gloss-maps) define the shininess of the material. They are conveniently created together with or derived from their diffuse-map. Bright values mean that the material is mat. Note that specular-maps are not limited to gray-scaled images: Their tone (color) modulates with the color of the light source. Specular-maps often have the strongest impact on dynamic lightning. Note that for many materials that only have diffuse light reflection characteristics (e.g. sandstone), specular-maps can often be omitted entirely.

Luminance-maps define the light that a texture emits. As with specular-maps, they are easiest created together with their diffuse-map, and often very simple in nature. The light of luminance-maps is local to the texture, and does not cast on any other surfaces or objects. Typical occurances for luminance-maps are with LED panels or computer-screens, but frequently they are not present at all, because most materials do not actively emit light themselves.

Height-maps (also called bumb-maps) are gray-scale images that define the height of a surface: dark is low and white is high. They often only serve as an intermediate product for creating normal-maps. In fact, Ca3DE converts all height-maps to normal-maps internally before use. Some people convert the diffuse-maps to gray-scale images in order to obtain height-maps, but this does almost always yield in bad quality It's just a lazy trick that you should never use. Instead, you should rather draw the height-maps properly. This is almost always very difficult though, and works best with either natural or organic materials or high-frequency components like scratches, dents, and so on. Another method is to obtain height-maps from the depth buffer information of some rendered geometry. In this case, however, I'd recommend to skip height-maps entirely, and render normal-maps directly from geometry.

Normal-maps are the most important component in dynamic lightning. They contain information about the shape of the surface. They are normally never hand-made, but rather derived (using a software tool) from height-maps. Please note that, according to practical experiences, combining diffuse-maps and normal-maps that both have high-frequency components (and the diffuse-map possibly high-contrast colors) tends to compromize the effect of dynamic lightning.

Summary: Only diffuse-maps are needed but additional textures can change the appearance of the texture dramatically. Height-maps are not necessary because Ca3DE uses the normal maps for them.

textures/filetypes.1126552535.txt.gz · Last modified: 2013-01-07 12:07 (external edit)