Parts of geometry dissapearing

[ksgfx]

I'm not sure if this is a bug or just a feature that v-ray doesn't support, sorry if it is the latter.

Here is the setup. I have two teeth setting on top of each other. One is cut in half and the other one is whole and slightly bigger (so faces don't coexist in the same space). The whole one is using the visibility track to reveal the tooth cut in half. The problem is that while the whole one fades out part of the half ones faces dissapear, untill the whole one is completely gone. Here is the image, notice the missing faces on the top of the tooth next to the probe:





Here is what it looks like after the whole tooth is completely gone:





I'm stumped. Has anybody seen this problem before? Any resolutions?

[Syclone1]

I have had similar issues and found the best way was to render 2 seperate camera passes, in your case one with the entire tooth and another pass with the half tooth and composite them later in your prefered nle video editor.

-dave

[vlado]

Which VRay version is that?

Also, do you have the Secondary rays bias set to more than 0.0?

You can try scaling your scene up, in case the distance between the two surfaces is too small and VRay cannot distinguish between them.

Best regards,
Vlado

[ksgfx]

I love the fact that you guys are so responsive.

The v-ray version is .13. I'm in the middle of a pending deadline and don't want to upgrade right now. Is it something that may be corrected in .15?

My Secondary rays bias is .01.

The scale is actual size, so the distance between them is probably less than 1mm. Everything I do needs to be to scale so I hesitate to scale it out of proportion.

[vlado]

My Secondary rays bias is .01.

Reduce it to something like 0.001 and it will probably be fine. If not, you may need to rescale the scene, or at least change the generic system units.

Best regards,
Vlado

[ksgfx]

Thanks vlado, that seemed to do the trick. Does that lower setting increase render time? I've notice it has now gotten quite a bit slower but not sure if it is that or some other tweaks I did?

[vlado]

Well, it should not slow things down a lot, but VRay has some more work to do - now it must shade the parts that were missing before.

Best regards,
Vlado

[dbuchhofer]

So basically what the secondary ray bias does is if 2 planes are very very close to each other (within the value set in the dialog), it will remove the one furthest from the camera from the rendering?

[vlado]

So basically what the secondary ray bias does is if 2 planes are very very close to each other (within the value set in the dialog), it will remove the one furthest from the camera from the rendering?

Not exactly. It will intersect the first plane properly, but will skip any geometry after it that falls within the bias value.

Best regards,
Vlado