When using EEVEE Volumetrics the minimum Tile Size is limited to 2 pixels. Why it is not possible to use 1 pixel or even 0.5 pixels?

Using higher Global Sampling does not help to refine the VDBs, since the Volumetrics do not seem to react on changes there. (You can check this by setting Vol. Tile Size to 16 px and then render with different Global Sampling - in all cases the Volume is blocky)

  • $\begingroup$ That is due to a GPU limitation. Lower tile size would allocate textures that don't fit on a GPU anymore. $\endgroup$ – J. Bakker Nov 30 '20 at 15:30
  • $\begingroup$ Thank you for the insight. But modern GPUs have lots of RAM. So this should be available, maybe when selecting "Experimental Options" or with a Warning... $\endgroup$ – rs3d Nov 30 '20 at 18:50
  • $\begingroup$ It is not about VRAM, but about the maximum 3D texture size the driver let you allocate. When hard coding the tile size to 1, I wasn't able to allocate the needed texture and Blender will crash due to that reason. $\endgroup$ – J. Bakker Dec 1 '20 at 9:46
  • $\begingroup$ Ah, thanks, that makes sense. What kind of VDB resolution you were using? Some smaller grids, like 64x64x64 are so small in the first place, that they are probably downsampled without need. Maybe you could have the 1 pixel option with grids smaller than the specific grid size that crashes? Thank you :-) $\endgroup$ – rs3d Dec 1 '20 at 14:19
  • $\begingroup$ Hi J, what is the maximum 3D Texture size after all? $\endgroup$ – rs3d Dec 4 '20 at 11:27

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