after some confusion, then research I realized you can't pack .vdb files into blender files for sending. This is a zip file with the single frame of data it needs.
Sat, Oct 17
Fri, Oct 16
@Richard Antalik (ISS) here you go. The issue happens in both GPU and CPU, so you can use either. This just has the simulation frame I used for that animation packed in. Note how extreme I made the shader in order to make the issue visible without using an alpha mask. I checked your file, and when I used my shader on it, your issue, with the "flickering density" became my issue with the "pulsing shadows". I can only assume it looks like flickering because in your cases the clouds are so small, the "density gap" passes over them in only a frame or two. The smoke ball is about 1.5x the size of your entire cube, and I think it's related to raymarching
Thu, Oct 15
could this be related to/the same bug I reported? they've both been in blender for quite some time, I feel it likely has the same or a related cause. Because the alpha channel makes it so much more noticeable, it probably has to do with some kind of uneven sample distribution, where rays are more likely to return a value right at the end of a step, or are less likely to right after one. This makes the volume react as if it had bands of density. Can you confirm if it is only happening when the camera is inside the volume for you?
Wed, Oct 14
Tue, Oct 13
Sep 9 2020
renamed for clarity of scope and succinctness- the description should probably be where the supposed cause or influencing variables go, not the title, and it was overly redundant. Apologies for the multiple edits- kept finding out of date information, files, and redundant text, and my current test file was far better at exposing the bug/artifact. >