I've been working with the renders of Roy's Revenge for awhile and have come across a problem with my outdoor scenes. In the scene, Princess, Roy's next door neighbor's dog is white standing in some green grass and a big blue sky. But there's a problem, when it renders with Final Gather it looks like this:
As you can see, the green from the grass and the blue from the sky bleed onto Princess and makes her look ugly. Why does it do it? It's the way Final Gathering works, it makes everything a light source, so the giant green ground the little dog is standing on becomes a giant green light.
How do you stop this? Well, I figured out how.
First create a giant grid to cover the ground and set it a couple of inches (in terms of the scene scale) above the ground. In my scene, it's just up to Princess's ankles. Then give it a new material, Pong, and make the Colour, Ambient and Specular all white.
Once that's done, go to the Selection Button on the Right and select Visibility. In the Rendering portion of the Visibility deselect Shadow Caster and Receiver since we don't want this thing to give off shadows. Then turn off the Primary of the Ray Visibility off. Here's the result:
Ta-da! Fixed! Princess is no longer greenish! I also do it with the sky so Roy doesn't turn up blue.