Each camera in the model is capable of producing output. Therefore, each such cam-era must have the destination of that output specified. That is done by means of the pix and mask components of each camera. Setting the output destination with the matte parameter will apply only to the first camera. Subsequent cameras must have the components specified. The matte parameter is included simply for compatibility with previous versions of SDL. Users are encouraged to use the camera components instead. See the description of those components for the de-faults used, and for the order of priority among the command line option, the components, and the matte pa-rameter.
The matte file specifies how the image must be weighted when compositing. When using a matte for compositing against another image, the scene should be rendered with composite_rendering = TRUE..
The <filename> can be a full or relative UNIX pathname. Relative path names are applied with respect to the current working directory when the renderer is in-voked.
When animating several frames in an animated sequence from a single SDL file, the number of files (and their names) depends upon the renderer.
For the Raycaster or the Raytracer, a series of files with names in the form <filename>.<integer> are created. Note that this extension is in addition to (and ap-plied after) any other extension that may exist as a result of using a filename variable.
matte output is ignored when using the wireframer.
