Autodesk 12812-051462-9011 User Guide 3 - Page 1088

"Screen" Compositing for Specular and Reflection Elements The other exception to additive composition is when specular or reflection elements have been generated by certain material shaders. These shaders generate specular and reflection elements you must composite differently: ■ Anisotropic ■ Multi-Layer ■ Oren-Nayar-Blinn Shaders are assigned on a per-material basis, in the Material Editor. If you render specular or reflection elements in a scene that uses these shaders, then composite them with the diffuse and other foreground components (aside from colored shadows, as described above), by overlaying them using an operation called "Screen" in some compositing programs. Screen compositing uses this formula to combine elements: Background * (1 - Foreground) + Foreground The background is multiplied by the inverse of the foreground color, and then the foreground color is added to the result. For more information, see the documentation for the compositing program you use. Procedures To have the Render Elements dialog assign names to the rendered element files automatically: 1 Assign an output file name and file type for the (entire) rendered scene using the Files buttonFiles on page 6129 on the Common Parameters rollout of the Render Setup dialog. 2 On the Render Elements rollout, use the Add button to specify elements for rendering (see following procedure). To render elements to files without rendering the entire scene to a file, follow this procedure, and then turn off Common panel > Common Parameters rollout > Render Output group > Save File. To add an element for rendering: 1 Click Add. Render Elements Panel and Rollout | 6343