The following images were created by testfilter.c which was used to call libprman.a and librdc.so to print out ASCII WaveFront Object files that show sideviews of the various RenderMan Standard filters. The WaveFront Object files were imported into Alias to create the final images below which are simply window captures. Notice that the filter is shown from 0 to 3 even though the filter's actual range would be from -1.5 to 1.5. This range is why RenderDotC suddenly switches to zero at 1.5 where the filter is in fact supposed to stop.
Keep in mind that filters are normalized by the renderer as stated in the specification, so even though two curves may have radically different heights, once normalized they can become the exact same curve. Take for example the CatmullRom filters shown below. Once both are restricted to a range of -1.5 to 1.5 (in this case 15 grid units to left and right) and normalized, these curves become identical filters.
The PRMan filter is shown on the left and the RDC filter is shown on the right.
