I tried rendering an scene today with the branched path tracer and found that Blender always crashes after a minute or so of rendering (several tiles have been rendered at this point). The exact message is the rather mysterious “Blender has stopped working”:
- The scene has 4 layers (objects, lighting, particles and volumetrics). The scene renders fine if I only render layers 1, 2, 3…or 1, 2, 4…but it always crashes at some point if I try to render 1, 2, 3 AND 4.
- I’m using the latest version of Blender 2.73 64-bit, downloaded today.
- My computer has 32 GB RAM and I’m CPU rendering on a stock i7-4770k.
- According to task manager I have at least 9 GB of RAM spare at all points during the render, including at the point of the crash. Blender was reporting a steady memory usage of 6837 MB.
- If I change the number of samples, then more of the image is rendered before the crash occurs, if I increase the samples then less of the image is rendered.
- I am using the standard feature set.
- The scene renders fine with the standard path tracer, but it is incredibly slow in comparison. I don’t know why exactly this the case for my scene, but a quick test I did now to demonstrate this showed that I had comparable noise in a 3 minute path traced render vs 15 seconds in the branched path traced render. Given that my final render is going to take many many hours with the branched path tracer, I know now that the normal path traced render would take a prohibitively long duration.
Branched path settings:
- 1 sample for every type (diffuse, glossy etc)
- 0 clamping
- Tested with 1 to 100 AA samples (square option not checked)
- Sampling all direct lights
- Sampling all indirect lights
- Sobol pattern (tested correlated multi-jitter too)
I actually had this problem with all the earlier versions of Blender too, but I’d never paid it much attention since I wasn’t near the rendering stage with a project that was affected by the problem.
Any ideas why I can’t render my volumetrics and particles layer in the same pass when using the branched path tracer?