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I am trying to bake a normal map (Currently trying to do 16384x16384, will downsize to 4096x4096 as compensation for no AA). The high poly object is ~750k poly while the low-poly is 1.2k. No matter the tile size and other optimisations in the performance tab, blender fills up 32GB of system memory + 32GB of swap in about a minute and crashes. I know the resolution is very high but this much memory seems abnormal. I'm using Blender 3.3.0 on Linux, baking with Cycles on CPU, any ideas?

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Not really an answer, more an analysis that wouldn't fit a comment....

If I am not wrong:

Baking is done with all four RGBA channels of each 32 bits depth.

$$ 16\,384\times16\,384=268\,435\,456\mathrm{\,pixels}\\ 32\mathrm{\,bits}\times4\mathrm{\,channels}=128\mathrm{bits}=16\mathrm{\,bytes}\\ 16\times268\,435\,456\approx4.29^{9}\approx4.29\mathrm{\,GB} $$

Now, I don't know what amount of memory Blender needs for the baking itself, but surely it isn't much.

So... Maybe try the menu Help > Report a bug? If it's abnormal behavior, we can't do much about it here aside telling you to use lower resolutions.

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  • $\begingroup$ I stumbled upon this bug report when researching, as a temporary workaround I added another 32GB of swap to see if it'd be enough to complete the bake, it's been going for a few hours (probably most of that time was swapping from memory to SSD) but so far, it seems like you'd need ~90GB of memory. $\endgroup$
    – ppk
    Commented Sep 19, 2022 at 3:04
  • $\begingroup$ Oh yeah, nice catch! Since it's a confirmed high priority bug, and it also seems that they want if fixed for the next bugfixes of the 3.3 LTS versions, ai think we can hope it will be dealt with quickly. $\endgroup$
    – Lauloque ♦
    Commented Sep 19, 2022 at 7:41

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