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gamedev:textureproperties:absorption_range

Summary

Texture Property Nameabsorption.range
DescriptionDefines the sub surface absorption range.
Excepted Data Source1 component value
Data Range0 or grater
Default Value0
Affected ModulesGraphic
Linked Propertiesabsorption

Description

The absorption.range texture property defines the range of scattering in sub surface absorption of a material. Sub surface absorption affects light entering the material after surface based texture properties have taken effect. Sub surface absorption has two main effects. The first is that light is scattered under the surface and exits at a nearby point. The second effect is translucency. In both cases the absorption.range texture property defines the range of absorption. Beyond this limit the light is fully absorbed by the material. In between the light is partially absorbed using an exponential decay function. In contrast to the absorption texture property the absorption.range is a single component value and defines the largest radius. The actual absorption used is thus absorption times absorption.range component wise. See absorption texture property more information about absorption.

The source is a value with 1 color component with values 0 or greater.

The default value for this texture property is 0 which disables sub surface light absorption and scattering.

A value of 0.02 is a typical choice for human skin. Most materials have absorption ranges below 0.1 .

Note on the values in the examples below. The stanford armadillo model is small. If you want a full size 2 meter high armadillo to show these absorption properties you have to multiply the range by 10 to obtain similar values.

Examples

Stanford armadillo with 0 absorption range and back-lit.

Stanford armadillo with 0 absorption range and back-lit. No light penetrates in this situation. A good choice for solid materials like stone.

Stanford armadillo with 0.02 absorption range and back-lit.

Stanford armadillo with 0.02 absorption range and back-lit. This matches human skin and yields translucency on extremities where geometry thickness is low.

Stanford armadillo with 0.05 absorption range and back-lit.

Stanford armadillo with 0.05 absorption range and back-lit. With larger radius value light starts to penetrate also thicker geometry like the legs.

Stanford armadillo with 0.2 absorption range and back-lit.

Stanford armadillo with 0.2 absorption range and back-lit. Extreme radius example resulting in heavy light penetration. This one looks like jelly doesn't it?

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gamedev/textureproperties/absorption_range.txt · Last modified: 2014/03/30 16:34 by dragonlord