Cineversity

I’m rendering my scene using the Physical Renderer in C4D R18, and I’m getting these dark splotches in my render that move around. When I disable GI, they disappear, so I’m assuming it has something to do with that. I have a number of lights that have area shadows (which I’d like to keep), although turning off shadows for those lights also appears to fix the problem. I’m using Irradiance Cache as my primary GI method with Light Mapping as my Secondary. I saw reference to splotches in the manual under the Irradiance Cache’s smoothing feature, but while that does change the image, the problem remains.

I attempted to change the Samples, and while it made it a little better, it was still there (and render times increased dramatically). What things might I try to fix this?

Hi vidox,

Without a scene and perhaps some “investigative” it is certainly not easy to say, just from three tiny little images. These look like a scene from a Pin ball machine, and they would be fast I assume, so Motion Blur. They show up even in Motion blur?

When you shut GI off the problem stops showing, but that doesn’t mean it is GI. Perhaps the samples of the Area Shadow are just too low, and here the problem start. (Which is grayed out in Physical and needs to be adjusted with the Shadwo Subdivision (mAx) parameter) But I start to guess and I always think that guessing is not pro like.

I suggest to have a look here:
https://www.cineversity.com/vidplaylist/the_physical_renderer/the_physical_renderer_-_part_5

Of course the whole series and Patrick’s series about GI shouldn’t be missed.

If you need an upload link let me know. But please reduce the scene to the problem, I do not have a lot of render power here, as the support would have.

All the best