Hello, having a weird issue with the upres Fluid node...
I have a pretty low-res base simulation, and when I apply the upres node everything works as expected, but when I render the high res simulation my simulation will "soften" and expand very slightly midway through the render, causing a visible jump in the fluid. I have confirmed this isn't a render issue, as the jump is noticable in the actual working scene, and is present in the upres fluid cache.
Thing is, this seems to change its timing depending on how much I multiply the base fluid. Let me describe an example...
Lets say I have a 300 frame animation, with a starting multiplier of 3. Rendering the whole high res sequence looks fine and stays consistent, but the resolution is still too low for a final.
I increase the multiplier to 6, and now when I render, the upres fluid suddenly softens and expands on frame 250. This causes a slight flicker or jump in the render when it changes, which isn't desirable. Before frame 250 everything looks fine, and after frame 250 it continues with the softer version to the end.
If I now increase the multiplier to 8, the softening still happens, but now it happens sooner, say on frame 100.
If I increase the multiplier to 12, the softening happens really quickly, like frame 10 (before the fluid is visible to the camera), but now the size of the cache files is too large and the scene is too slow and cumbersome to work with, let alone render.
Just for the record, I'm NOT using auto resize. Since that seems to be the problem most people are making out of the gate, I wanted to make sure I mentioned that up front.
Anyone know why is this happening?