When rendering an image in cycles render, I find that lots of the time is spend rendering completely blank tiles, especially when I have high samples. Is there any way for blender to know when a tile does not have anything in it and skip rendering it? If not is there any add on that can help with this? Thank you for all your help.
1 Answer
There is no automatic way.
Cycles render engine uses path tracing to render a scene. In order to calculate whether there are additional objects that might cast light/shadow in a scene, it has to calculate the whole scene based on the camera's view.
The only method for Cycles to get that information before the final render would be through pre-processing, which in the end would take more time than rendering empty tiles.
However, you can restrict the render area by using the Render Border feature. Hit 0 on the Numpad to enter Camera View, then hit Ctrl+B and draw a box around the area you want to have in your final result.
Now only the selected area gets rendered and the result gets resized to the final image's size.