LuxCoreRender Forums

This keeps coming back again and again.

opencl cpu even on cpu some very thin and long triangles show up black! It's just that opencl is more sensitive to the issue... It almost looks like some overlapping is happening..

raising min epsilon won't help and main scene contains volumes so even if it helped it might give me problems with volumes..

scene note:
In this particular case I know how to fix stairs, but the back wall would need more work and I've been given CAD files from people where I cannot simply tell them how to tesselate meshes so that luxcore doesn't have issues with it, so it can easily turn into unsolvable problem.

And even when I have option to tesselate meshes on my own it requires a trial and error

tesselated stairs

I use this to help fix imported CAD (stl) files. It works quite well. I hope it helps

https://github.com/wjakob/instant-meshes

Racleborg wrote: Mon Aug 19, 2019 8:48 am I use this to help fix imported CAD (stl) files. It works quite well. I hope it helps

https://github.com/wjakob/instant-meshes

Thanks... but this is a bug and needs fixing.

small triangles can make luxcore flip out too...
and if I move camera closer they tend to disappear changing min. epsilon isn't helping

please can we see a wireframe of the same view ?

Sharlybg wrote: Tue Aug 20, 2019 9:37 am please can we see a wireframe of the same view ?

I don't know what you hope to gather from that but here you go

Bevel modifier???
See if you apply it, are there any weird overlappings or onmanifold edges.

There are no modifiers, and no custom shading and no overlapping faces...
Mesh has coumple ngons, but it doesn't matter if I triangulate it manually...

Also the defect changes with angle of camera sometimes it seems Let me make one thing clear. I know how to fix this or the stairs mesh scene I posted if I really want cause these are my meshes... But:
A: I can't always fix this
B: Even when it can be fixed it is sometimes a lot of extra work that's usually not needed with other renderers
C: Issue is also present in cpu rendering but a less visible sometimes

lacilaci wrote: Mon Aug 19, 2019 8:36 am This keeps coming back again and again.

opencl
trianglesGPU.png
cpu
trianglesCPU.png

even on cpu some very thin and long triangles show up black! It's just that opencl is more sensitive to the issue... It almost looks like some overlapping is happening..

raising min epsilon won't help and main scene contains volumes so even if it helped it might give me problems with volumes..

It looks like a different problems (if there is a problem), if I just disable bump mapping on the used Disney material (or replace the material with a plain white matte), I get a good rendering, both on CPU and OpenCL:


So, it is not the geometry problem you are talking about. I don't know how the bump was intended to affect the rendering (or if it was intended at all) so I'm not sure if there is a problem at all.

Do you have a different test scene where the problem is really related only to the geometry ?

Dade wrote: Tue Aug 20, 2019 1:43 pm

lacilaci wrote: Mon Aug 19, 2019 8:36 am This keeps coming back again and again.

opencl
trianglesGPU.png
cpu
trianglesCPU.png

even on cpu some very thin and long triangles show up black! It's just that opencl is more sensitive to the issue... It almost looks like some overlapping is happening..

raising min epsilon won't help and main scene contains volumes so even if it helped it might give me problems with volumes..

It looks like a different problems (if there is a problem), if I just disable bump mapping on the used Disney material (or replace the material with a plain white matte), I get a good rendering, both on CPU and OpenCL:


gpu.jpg


So, it is not the geometry problem you are talking about. I don't know how the bump was intended to affect the rendering (or if it was intended at all) so I'm not sure if there is a problem at all.

Do you have a different test scene where the problem is really related only to the geometry ?

Oh shit, you are correct... This was happening cause there was missing UV map on those meshes...
If mesh has uv's it all works fine. I keep forgetting that it is a problem in luxcore.

no uv map: with uv map: