prman -rif RIBBound.so rib-files
RIBBound.so is a rif plugin provided with prman. It tracks the world-space bounding box of a rib stream and prints it to stdout on close. Procedural bounds are used as given in the rib; the procedurals are not cracked open. Transformation and deformation motion blur are taken into account.
RIBBounds.so only works with prman; it will not function correctly with catrib. To find the bounds of a rib file without having to actually render it, the -catrib prman option can be used to prevent actually rendering an image.
prman -rif RIBBound.so -catrib /dev/null foo.rib
Pixar Animation Studios