Just standing in RT-Mode needs 100% CPU

[Anonymous]

Hi there,

I have a strange behavior with a VRED-file. If I switch to RT (without antialias), all 56 Cores go to 100% - and stay there. So it's not even possible to switch antialias on, select render.layers and so on...

I already optimized the model and the scene, but nothing works. It is a complete car, almost 2.1GB large, a view lights and a white backplate. So, nothing unusual...

What can be the problem?

Thanks, Clemens

[michael_nikelsky]

Hi,

this is very hard to tell without knowing what settings you use, which RT-Mode and so on.

Here are some things that can cause Problems:

- high trace depth with multiple glass surfaces in another mode but FullGI. This can lead to ray explosion since each glass surface will trace 2 rays, one for reflection, another one for refraction. Having for example 8 layers of glass means it will have to trace 256 rays per pixel, having 16 layers and we are already at 65536 rays per pixel. This should not be a problem in FullGI since only on raypath is calculated.

- displacement mapping on a poorly subdived surfaces or on a surface with UV-coordinates going all over the texture in one place. This forces the raytracer to basically check every pixel in the displacement texture once or multiple times, depending on how often the texture is repeated accross the surface of one triangle.

Anything else is impossible to tell without having the scene.

Kind regards

Michael

[Anonymous]

Hi Michael,

hmm, I'm using the standard settings, but I'll crosscheck this again. I noticed there is a warning if I start up VRED (see image).

I'd love to give you the scene to check, but - as always - the scene is based on OEM-Data and therefore secred. Umless you have an KVS-Account, I'm unable to 😕

CU, Clemens

[michael_nikelsky]

That warning can be ignored, it will revert to SSE42 or SSE2 if the DLLs are not found.

[Anonymous · Accepted solution]

Hi Michael,

that was a good tip, regarding the material! My first guess were the tires, but they are ok.

So I went and have hidden geometry, switched to RT and watched my CPU's until I identified (after an hour sor so...) a light material in the steering wheel. I gave the symbols a light using dragging a retangular with the mouse around them. I didn't realize that all (not visible) geometry beneath the symbols got this light material, too. Changed that to plastic - problem solved!

Just 4 Info, if someone else runs into that behavior 🙂

Kind regards, Clemens