.RPF File Extension

what sort of things can you do with an RPF sequence? and what are the advantages in doing such things in a seperate compositing application?

RPF files are a type of multi-channel image for use in compositing. They're most often created as image sequences by 3D rendering software such as Autodesk's 3ds Max, and they're used to include any number of channels beyond the normal red, green, and blue. For example, you can include an alpha, object ID, Z-depth, or normal channel. The RPF image sequence is then opened in a compositing program such as Adobe After Effects, which can make use of the additional channels. For example, the Z-depth channel can be used to create a adjustable depth-of-field look. Unfortunately, most software can't read these files, including Photoshop.