Mental ray's mia_material is a versatile, physically correct shader which is the right choice for Final Gathering. However, final gathering is not a cheap and easy solution for animation. In many cases,
a traditional "Ambient light" approach for simulating indirect illumination is still a popular solution.
The problem is the mia material doesn't respect Maya's ambient light. They don't interact at all by default.
So, I'm going to show how to make a mia material respect Maya's ambient light.
Here's a simple scene, a plane and the dragon.
A Lamber shader si assign to the floor and a mia material is assign to the dragon.
The only light source in the scene is just a single ambient light.
The below is the render result.
