Watertight ray triangle intersection

Gaming and Visualization Technologies Visualization OptiX
1

Hi, I remember we had issues with ray-triangle intersections back in optix 6.5 when by chance a ray would intersect triangles along their shared edge and fail to intersect with either of the triangles.

It appears to have been fixed in optix 8.0 - it works flawlessly from what I can tell. But I can’t seem to find any mention of that in the documentation / release notes.

I see that there is a patent that was filed on behalf of Nvidia: US20220230380A1 - Watertight ray triangle intersection - Google Patents
Also Detlef mentioned that HW-accelerated ray-triangle intersections are watertight.

And so I am wondering, are watertight ray-triangle intersections something that was introduced at some point in of the >6.5 versions? It wasn’t a thing in 6.5, was it? Thanks!

2

Hi @rastislav.starkov,

The RTX hardware supports watertight mesh intersections, and that’s independent of OptiX versions. Since RTX was introduced in OptiX 6, watertight intersections have existed at least since then. I just asked around and I’m told there were efforts to make things watertight in earlier OptiX versions, though it might have been incomplete or had a more strict set of requirements in order to work effectively.

In terms of documentation for the feature, DirectX documents the watertightness requirements, and our ray tracing driver supports DirectX, Vulkan, and OptiX. DirectX Raytracing (DXR) Functional Spec | DirectX-Specs

–
David.