Not Possible to Export Object as FBX with 38mil. Polys. Blender Performance Abysmal

Hello,
I’m currently working on a game prop, which I want to paint in Substance Painter. I sculpted the model with a multires modifier, baked a normal map from the multires high poly source, exported the low poly model as FBX and now want to export the high poly model as FBX to use it for mesh map baking in Substance Painter.

The problem is that Blender just doesn’t seem capable of exporting such a high poly model as FBX. It either freezes my computer, crashes to desktop or just aborts the export process after some minutes without exporting the model but going back to be responsive (as if I’ve never chose to export anything).

I understand that it’s not a lightweighted model, but why is Blender having such a horrible time to deal with high poly models on export? Is there anything I can do? I really don’t want to fall back to more capable software in regards to high poly handling.

Here are my export setting:

My pc specs:
Intel I9900K
RTX2070
32GB DDR3 at 3200 Mhz

Blender version 3.3.1

have you applied modifiers before exporting? does blender work fine after applying modifiers?

I have applied the multires modifier before exporting. I have not tried to let the exporter apply the modifier on export, since I have little confidence that more work upon export will lead to an improvement, but I could try.

Have you decimated at all? 38 million polygons is a lot even for a high-poly sculpt. I would bet that you could drop down to 16 million and you wouldn’t be able to see a difference at all

While I found out that I don’t really need the highpoly mesh in Substance Painter, since I already baked a normal map from the high poly mesh in Blender and just can use that, I’m still a bit baffled by the export performance (luckily, I don’t actually need it in my case).

I tried to export the model with a subdivision level less, making it roughly 10mill polys, it still took Blender roughly 5-6 min to export it. All the time Blender was in “no response mode”, so I already thought Blender had crashed again.

However, I lose a lot of detail going from 38 to 10 mill polys.
I’m making a mountain basecamp tent and I lose half the detail of the zippers for example.

I have yet to try a middleground between 10 and 38 mill. but it’s not fun to experiment let alone work with such performance on export (NOTE: sculpting with 38mill. polys, didn’t seem to be huge problem for Blender, neither baking the normal map).

Well, since it’s getting late, I’m not continuing experimenting today. I may make another try to tomorrow, but since I’ve found another way to get the details to Substance Painter for now, I won’t pull out a leg to get it working in the original way I had planned.

That being said, while I’m aware it’s a high poly model, 38mill polys pure geometry, no shaders, no node setups etc. I think it’s not that high for 2022 and the hardware around.

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