OTOY Forums

Hello,
I am coming across something when using large volumes and need to increase the voxel size quite a bit for performance. After increasing voxel size above a certain number the fog starts disappearing and then reappearing in the render viewport as you continue to increase the size, resetting the grid to 0 x 0 x 0 before reappearing with correct grid size as you continue to increase voxel size value.

It seems to happen when the voxel size goes above the height of the mesh in testing.

But the strange part is that sometimes it does show the volume and does work even when the voxel size exceeds the height of the meshvolume.

See attached scene, the voxel size should be 199m and the height of the mesh is 200m if you keep increasing this voxel value past 200m (make sure to have renderview open) you will see the mesh appear and disappear at certain intervals all the way up to say 1000m voxel size.

Not sure if this is actually an issue or just how the grid is calculated?

Thanks

Don't worry i dont think this is actually an issue. I did a bit more digging, and apparently, this is how voxels are calculated and displayed and it's directly tied to the voxel size relative to your volume bounds.

For example

Your volume container is 500 meters tall

Your voxel size is set to 100 meters

That means Octane slices your volume into just 5 vertical layers (500 ÷ 100 = 5)

But voxel grids are center-sampled, not edge-aligned — so:

The first and last voxels only partially cover the top and bottom edges

Visually, this "chops off" the top/bottom as the interpolation fades out

This becomes more visible with low voxel resolution (larger voxel size)