When this is happening, it is necessary to give PhotoRealistic RenderMan both a larger clipping region and a smaller threshold for giving up. Here are a few other tricks you can try as appropriate to cut down the overall rendering time and limit memory usage. It is important to notice that fine details on an object that is heavily motion-blurred are simply not visible. Only broad bands of color will be seen in the final image. For this reason, it is advantageous to set a very large shading rate for fast-moving objects.
Displacement maps are almost always inappropriate, for the same reasons.
It also cuts back the amount of memory required to maintain the object description over the large portion of the screen it influences. A RIB file that has been converted to binary encoding will use about half the disk space, and will load into PhotoRealistic RenderMan in about half the time. This can be crucial when using very large polygonal models. This process can be done using the catrib program, or the modeler can request binary encoding when it is creating the file. It is important that this be set correctly, because PhotoRealistic RenderMan uses this value to calculate how much earlier than normal the object must be handled.