I am encountering some strange lighting behaviour when rendering with cycles when using a glass material. I wanted to make a render of my building and turned on the raytraced viewport, which yielded the following result.
As you can see, the lighting in this is way different. I then used the normal render function and it resulted in the same lighting as the higher resolution -viewcapturetofile.
Trying to find the cause of this behaviour, I changed the render processor from my GTX 3060M on CUDA to my Ryzen 5 5600h. Using the raytraced viewport then yields me this image, which is again the same as my double resolution variant: (don’t mind the grain, cpu rendering was very slow).
Now when I switched back to GTX 3060 CUDA the rendering also looks like the second variant with more lighting. I cannot get it to go back to the way it was before. Neither of the lighting behaviours through the glass looks right to me however. In the first version the glass almost completely blocks out the light, while in the second version it blows the light way out of proportion, and makes it brighter than it should be.
Is this a bug or does anybody know a solution to get correct and consistent lighting behaviour?
If you can upload your model using Rhino - Upload to Support I can have a look this week to see what is going on. Obviously the results should be the same across all ways of rendering.
For what it is worth though you can also just use _Render command since the Rhino Render in Rhino 7 is essentially the same as Raytraced - exactly the same render engine is used. It will be less stressing on your system resources since you don’t have to have a Raytraced running and then do a _ViewCaptureToFile. That uses double the resources. Just have your viewport you want to render in say shaded mode, then use _Render at the resolution you want.
Anyway, I’m looking forward to see your file for further investigation so I can determine if I have introduced bugs anywhere or not.
Also please post the full results of the Rhino command _SystemInfo.
Just to let you know I’ve received your file, and I am investigating now.
Edit: I don’t know yet how this is caused, but I think as a workaround for now set in object properties for your huge ground surface to not cast shadows. I believe with that you should be able to get better rendering results.
It seems my last message didn’t get through. My ISP is having some trouble with the mcneel forum. Thank you, I’m looking forward to hearing the results. I tried to disable cast shadows for the ground surface. This unfortunately didn’t change anything. Changing the sun direction suffices for my renders for now.