Crazy (Bad) Cycles renders

I am rendering an animation – simple, slow pan across a scene

about 75% of the frames turn out fine(see here)


However, from time to time this sort of thing happens:


And other times the fit hits the shan (see here):


Any idea what is up?

The purple in a render usually means that Blender can’t find a texture… The green, that’s new! Never seen… Are you sure your GPU isn’t over-heating just a little bit? When was the last time you used the vacuum cleaner on the fan(s)? :wink:

Well – if it was textures then there would never be a good frame rendered

It is set on CPU rendering (out of memory on the GPU) (memory is not an issue with the CPU)

Its the randomness of the issue that bugs me. I render a sequence and most frames are fine. Others are FUBAR. If I change the seed, the stats are about the same, though different frames work and others are crazy.

The purple/pink areas that you see is generally a universal sign of shading errors.

Perhaps it’s best to file a bug report, the fact the first image is fine discounts the possibility of user error when building the node material so it might be the possibility of the Cycles shader code throwing errors and/or getting corrupted instructions on certain materials when everything is re-initialized for some of the frame.

Submitted a bug report –
I don’t understand exactly what Sergey said – NaN were thrown about and that caused an error – solution is to use the clamp option in the short term, and there are some general stability/robustness tweaks that can be made in the long-term.

Once again, the Blender Foundation shows itself interactive and helpful. Thanks to them!