mental ray Architectural and Design Visualization Shader Library
mental ray Architectural and Design Visualization Shader Library
mental ray Architectural and Design Visualization Shader Library
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
5.3 Light Surface 113the other two has it set to 0.0. But the rightmost patch has a point light hidden behind it.At close distances (or with very large light sources, like the entire outdoor sky) FG canilluminate objects just fine with very good quality. At long distances or with small sources,using an explicit light source is much more efficient.mia light surface gives separate control if the object should be “seen” by reflection <strong>ray</strong>s orFG <strong>ray</strong>s (<strong>and</strong> how much) via the fg contrib <strong>and</strong> refl contrib parameters. This image usesa slightly reflective checkered plane to illustrate this. No light sources are used behind thesepatches:Visibility to FG <strong>and</strong> reflectionsThe leftmost patch is visible both to FG (illuminates the plane) <strong>and</strong> reflection (reflects in thefloor). The center patch does not illuminate (fg contrib is zero) <strong>and</strong> the rightmost does notreflect (refl contrib is zero).5.3.2.2 Highlights vs. ReflectionsIn the real world, the visible light emitting objects are both visible to any cameraphotographing the scene, as well as reflect (glossily) in other objects. In computer graphics,light sources tend to be invisible to the camera, <strong>and</strong> their reflections are “cheated” with thehelp of “highlights” by material shaders.The mia material supports a protocol for light sources to tell it if they should generatehighlights or not. This is implemented by most OEM applications light sources, look forflags like “Affect Specular” or “Emit Specular” or similar on the lights.Light hidden behind patch with various flags.