Sometimes is very useful to generate inverse occlusion bakes to reach an interesting starting point to paint our dirt maps.
Vray dirt material is perfect for this goal, but if you don’t work with Vray, is very easy to do the same with Mental Ray and Binary Alchemy Shaders.
- You need to install the Binary Alchemy Shaders. Some packages are free and you will have to pay for another ones.
- Apply a “surface shader” to the object and connect a “BA_color_raylenght” to it.
- Put this shader in “Inverted Normal” mode and play with his parameters.
- We get an inverted “ambient occlusion”.
- Use a “blend colors” , “layered shader” o similar to combine this inverted occlusion with a nice bitmap.