Cycles V Optix

Two questions:

  1. In 2.9 betas, there’s no obvious indication that Optix rendering is being used (If you select Optix in prefs, then that’s what Cycles seems to use.) In 2.8 it explicitely stated Optix as the render engine. Is this by design, or something yet to be fixed?

  2. Optix seems to either be slightly underlit compared with Cycles, or the brightest and darkest pixels are closer together across the spectrum. Is this also a bug, or by design?

I can’t share the renders I’m testing with, unfortunately. They are themed, and I’m saving for next month before I post. However, if no-one has noticed similar, I’m sure I can throw a scene together that will demonstrate the difference.

Having said that, Optix even on a 1070 (i.e. non RTX) is rendering about twice as fast with everything else the same.

Do you have an rtx card for optix? If not then the lighting issue might has something to do with the lack of specific ray traycing cores. If you select optix in the system settings then ut uses optix. You would need to select cuda or none for cpu or gpu rendering not using optix. Plus no matter what cycles is primarily designed for cpu so it will render more arcuratley on the cpu.

GTX1070 is non-RTX. I can tweak the lighting. The difference is tiny, and can only really be seen on a side by side comparison.

However, I also have a hybrid render of exactly the same scene going, which looks like it will now be the slowest of the lot. Probably because previously, I had a GTX 1060 and Ryzen 1800X which seemed well balanced. I guess the 1070 has overtaken the balance, meaning GPU only will now be faster.

With a 2080 ti and a threadripper hybrid rendering is still the slowest. Basically gpu is almost always fsster but the vram limit is pretty easily hit so cpu and ram is then optimal/only option.