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To define the surface material of each object, we have a diffuse(color) map that defines the color and subtle shadows of the object, and a specular map that defines which parts of it are reflective.  We then multiply the diffuse map with the diffuse lighting, and multiply the specular map with the specular lighting, and add them both together to get the composite result.  We will discuss how exactly we get the diffuse and specular lighting in a later post! 

One of my biggest goals for the Overgrowth graphics technology is to minimize the 'cgi look' that is common in games and movie special effects, where scenes don't quite look like they fit together.  I think we can drastically reduce that effect by simulating ambient and indirect lighting: how each object reflects the color of the sky and nearby surfaces.  Most games approximate this by just adding a flat 'ambient light' value to the shadows, but we are going a step farther and using blurred cube maps to simulate the true ambient light colors in every direction.