I’m working on this scene and from doing test renders I’ve found that the black curves on the floor in the pic below take about 35% of the time to render this scene. This seemed rather oddly long because those curves are just plain mi lambert shaded black surfaces. In comparison, those desks and chairs that have dielectric or some level of reflection on all surfaces takes up about 9% of the render time. The stairwell in the back which is entirely dielectric takes up about 8% of the render time.
After fooling with it some more I’ve discovered that what takes so long is the fact they are actually just perfectly rounded curves extended quite a ways. Because putting different shaders on the curves didnt change the render time much at all. From what I can tell when MR does the sampling on these curves it just takes absurdly long in comparison to straight edges.
Is this just how it is? or am i doing something wrong? Why do the curves take so long to render? Is there anyway to make curves like that render faster? My BSP settings are correct, I tested that thoroughly as well. The percentages stay just about the same for all min/max sampling settings and contrast ratios.
BTW I tried making the curves out of both polygons and NURBS with various surface sample settings. It didn’t change the render time by more than 1%, so it doesn’t have anything to do with polycount either.