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Daniel Whitton
03-02-2004, 10:45 PM
I am placing this post with opes of receiving feedback from the comunity on developing a strong understanding of some basic/advanced concepts on lighting with mental ray for maya.

I have been trying to establish alighting model for a BMW Z 4 that I have modeled 3 months ago. the last 3 months have been put to researching light and rendering. I have been using Rendering with Mental Ray and Digital Lighting and Rendering as my guides.

I'm posting a rendering of my car. It is by no means qualtiy and I hope to improve it with your help.
The scene is set up with 3 point lights emitting 100,000 photons each and sharing the same physical light shader with and intensity of 300. To make it easy to debug the light color and environment color are both white. Also I am using 500 Final gather rays.

What I can't figure out is the render is completly washed out when I add the GI to my render.

The wall is a DGS shader that is Diffusing white light. While the ground is a DGS Diffusing Black while have 100% Glossy refelctions. The render however is to different tones of grey.

If I omit GI and only use Fg the colors render as expected.

From what I understand so far is that when I use a physical light shader it suppresses the maya light shader and only calculates the physical shader which works from the inverse square law.The exponent value of the photon energy is suppresed when physical is checked on. Photonic energy is the intesity of the indirect illumination passed off by the photons as the bounce through the scene.
With that said I have tried atleast 20 different renders with various settings of photonic energy values and light energy values. I either receive dark or nuclear renders.
I set this up with a black floor and white wall and grey reflective car so I can hopefully grasp the concept a little better then render out more impressive scenes.

I beg anyone to please help with concepts,ideas,theories,anything to get this going in the right direction.

Thanks in advance.:blush:

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