'shadevis' is a tool designed to compute a per vertex, ambient occlusion term;
This term can be used for a shading effect, commonly known as ambient occlusion
shading, that is aimed to provide more faithful simple realtime rendering of rather complex meshes.
In practice tather than considering the ambient lighting to exist uniformally throughout a scene,
this approach determines the ambient brightness of each part of a surface to be proportional to the extent
to which the surface has "its outward view of its environment" free i.e. occluded, by other surfaces of the object. For example, the upper part of the David forehead is less exposed to its local environment than the nose and as a consequence it will be proportionally darker.
The most common techniques to compute ambient occlusion is based on shooting rays from each surface element to evaluate the quantity of light that reach it. Shadevis tools use OpenGL to accellerate this process by simply rendering the scene ortographically from a set of uniformely distributed directions and checking against the zbuffer if each vertex is occluded or not.
The Shadevis tool is oriented to handle rather large meshes, we have successfully used on a 8M triangle mesh of the David on a 512Mb machine.
We have used this tool also for computing the exposition of falling agent over the Michelangelo's David.
Please, when using this tool cite the following references:
R. Borgo, P. Cignoni, R. Scopigno
An easy to use visualization system for huge cultural heritage meshes
VAST<EFBFBD>01 Conference, Greece, Nov. 28-30, 2001. s
