material retouch using material node with vertex color.
Material retouch is control a shaded área by material node with vertex color. If you didnt get desired results in a tiny shaded área of a model, do you remake a modelé but, remaking it takes time. In other way, mensaje effects as typified by composite node give a 2d effect, thus, partially incorrect 3d. You can control Shading of model as like 3d painting by material retouch in short time.
First, Paint vertex color a Shading control área in red and blue at vertex Paint mode. Paint a bright área in red, Paint a shadow área in blue and, Paint a inefective Shading control área in black.
Figure.1: vertex color painting example.
Figure.2: material retouch material node.
Note: method of extraction of red or blue from vertex color using rgbcurve. Extraction of red is zero in all value of green and blue at rgbcurve. Finally, rendering your scene and adjust vertex color painting and material node structure for desired images.
Figure.3: left:normal Shading suzzane. Right:Concave retouch Shading suzzane.
It from colors, because Blender 2.45 not supported shader influence controls. Notice, material retouch is effect todo materiales only. Thus, inefective todo tracing and buffer shadows.
Locally controllable stylized Shading (english)
Locally controllable stylized Shading (Japanese)
Test of ton Shading retouch on 3d (Japanese,XSI)
https://artifacts, sakura, ne.jp/sakanaya/2007/10/3d.htm