I have a rather complex scene, with a lot of fur on one character; so I rather expected high RAM usage. What I did not expect was that RAM is used more between frames of an animation, rather than during the rendering itself. I want to note that this is not the building phase, there is no info at the top like during building, and building does happen after this “high RAM” phase. This is a ~1 minute 13 second phase before building where Ram is eaten (and I’ve often crashed to my login screen). I have decreased subdivision where I can, limited texture resolution, enabled and disabled tiling, and disabled spacial splits. No change to this “high RAM” phase. The only thing that did lower the usage was decreasing the fur multiplication by about 35X but that only lowered by about a Gig. Disabling the character with the fur did decrease it by 10 Gigs for “high RAM”, but only 2 gigs while rendering!
I am using:
Ubuntu 22.04
RTX 4090
32 Gib RAM
5900x
Blender 4.0
Considering that the ram usage is at a very specific and odd time, I am hoping that it is an easy fix of a toggle I missed in my searching.
…this… is an odd question… why do you expect any render software to use less RAM before it actually renders ?? There is some work to do before doing so and it may just not inform about any step in “the building phase”…
So may you can try some Debug Options:
Thanks for getting back to me on this. I am still new to most of the more detailed functions.
The odd part for me is that it uses so much more than the actual build/render step, being over twice what is used during render, tiling or otherwise. I have no simulation occurring in my animation that is not already baked, or part of armature controlled movement, so that should not be an issue. Right?
Shouldn’t the assets in frame still be in RAM during the render phase as they need to be calculated for light bouncing?
I don’t know the underlying function of each step and am going off explanations I have found to in the blender docs and tutorial videos. My assumption was that if I have everything visible in my scene and viewport on cycles, that the render phase would be what would take more RAM, as that is what does the complex lighting and everything, as well as what everyone complains about. and that if it uses too much I should enable settings that decrease RAM usage and lower texture size. However no setting seems to decrease this step.
It’s also very odd to me that this step does not change at all based on anything like texture size or tiling and only changemosts when removing assets, despite a majority of my visible assets being instanced. I’m building from source right now to see if that might help my issue, after that’s done I’ll try to record a video during the odd step to see if someone might be able to help me to lower it.
Some operations calculates in VRAM, not RAM. And when you take render, example textures, stores in the RAM and transfer to VRAM, but they do not remove from RAM.
Try disabling persistent data, and also try without the vector pass enabled (if the vector pass is enabled it will also calculate the previous and next frame). If no help, then also try increasing ‘dicing rate render’ in the render panel to 4 if you have adaptive subdivision in the scene.
…