Research and development

 Mantra :- Void Occlusion Shader

I always wanted to make an advanced Ambient light shader like the one mentioned in The Renderman Language Guide book by Rudy Cortes & Saty Raghavachary for Mantra.This was to be my first attempt at shader writing in Mantra. So here we are with a great deal of help from Mario Marengo I finally completed a working Void Ambient Occlusion shader that can sample colour from an environment file or use a defined sky colour and ground colour.It is really going to help in any lighting pipeline towards building a great lighting rig

A screen shot of the shaders interface all you do is assign it to a light  template. As you can see you have the ability to us look up a user defined sky colour or ground colour or you can add a spherical environment map often this will be a HDR converted to a .rat file. Also from the interface you can see the occlusion function tab with the ability to use bent normals.

The  render above shows just the occlusion in action with a sampled ground and sky bounce colour. Remember there are no lights in the scene.

This render shows just pure ambient light from the sampled colours.

This render is using an blurred environmnet map from a HDR 

A still from a test animation using the void occlusion shader to test render proving that writing out an irradiance cache will not cause flicker in the occlusion