Automatic Level of Detail


Air 6.0.10 and later can automatically reduce the number of polygons in a polygon mesh based on an object’s on-screen size and other factors.  Automatic LOD applies only to polygon mesh primitives.

Enable automatic level of detail for an object with the following custom attribute:

Attribute “render” “float autolod” [n]

where n gives an error tolerance when simplifying a model.  Reasonable values to try are 0.1 to 0.3.  A level of 0 disables automatic LOD.

Automatic LOD is also influenced by the “flatness” attribute:

GeometricApproximation “flatness” 0.5

which gives the maximum difference in pixels between the original surface and the simplified surface.  The default flatness value is 0.5.  A value of 1 or 2 will produce smaller final meshes.


A reasonable set of values to start with are:

Attribute “render” “float autolod” [0.2]
GeometricApproximation “flatness” 1

When applied to cloth, auto LOD may result in clothing that does not cover the underlying limbs.  Using a smaller autolod tolerance may help prevent this condition.  Another solution is to use an opacity map to hide parts of a limb that would be hidden by clothing anyway.


© 2001-13 SiTex Graphics, Inc.  All rights reserved.