reyes renderer also include ray tracers but they handle 3d data different.

renderman can even calculate the pixels of curves nurbs without breaking them down into polygones as far as i know.

the good thing about reyes is they are fast with displacements.
other renderer sucks in terms of speed and detail!

aqsis is also a kinda self made project. the support the api but do it their own way. no offense dudes!

claas