Coordinate Systems

In The NVidia GVDB Voxels programming guide, there are images that show both right hand and left hand coordinate systems. Page 11 shows Atlas space as left handed with x/y on the floor. Page 22 shows World and Index space as left handed with x/z on the floor. And then page 23 shows Atlas space again as right handed with x/y on the floor. I’m really hoping that all spaces are right handed. Can we get some clarification on this?

Yes, you’re right, there is a mistake with figure 2.3 (page 11). The positive directions are not labeled, and the x-axis should go to the right (not left). Despite that, I’m afraid to say (for you) that all spaces are left handed systems. With that correction, the atlas in page 11 and page 23 should both have X+ right, Y+ out-of-page, Z+ upward. The world & index system have X+ right, Z+ outward, Y+ up.

You noticed that World and Index space have Y+ up, while the Atlas has Z+ up. However, the Atlas orientation does not matter. If you want to think of the Atlas as also being like World space, X+ right, Z+ outward, Y+ up, that works just as well (atlas orientation is irrelevant). You just need to know that the Atlas expands with new bricks along Z+, due to hardware performance advantages from making that the growing direction.

Regards,
Rama