Vray Hair Shader won't render when camera gets too close

[frame48]

Just as title says. Very easily reproducible on any scene where the camera gets close to the hair strands. Moving the camera back fixes it, applying a Vray Material fixes it as well. When it does manage to render, a bunch of buckets flicker and go crazy.

Is this a known issue or limitation? Is it cause by the edge length on the render settings?

[daniel.kapsazov]

Hi frame48,

Thank you for reaching out to us!

Could you please specify which version of Houdini and V-Ray you are using? This information will greatly assist us in investigating the issue.

Additionally, it would be helpful if you could provide a short video or screenshot of the behavior and node setup.

[frame48]

Houdini 20.0.653

V-Ray for Houdini number:22693 hash:3e95b05 from 12 Apr 2024 01:25
V-Ray Core 6.20.07 [ceebd8e2] from 11 Apr 2024

Wasn't able to upload the hip file here. But here's a google drive link: https://drive.google.com/file/d/1w0V...ew?usp=sharing

I noticed it doesn't happen just for the hairs directly in frame, but if there's hairs out of frame close to the camera sensor it will also not render.

[frame48]

daniel.kapsazov Please let me know if the provided scene file works for you.

[daniel.kapsazov]

frame48

Thank you for providing the scene. It works perfectly on my end. Unfortunately, I was not able to reproduce the issue using the same versions as you. Please try updating your V-Ray version to the latest nightly version (22725 from July 10) and check if the behavior is still present. I’ll be here to assist further if the issue persists.

[frame48]

daniel.kapsazov Unfortunately we can't get it to work. If we let the machines run for long enough, eventually the IPR will pick it up. But as soon as the camera moves any further it will not render. Tried it on 3 machines at the office and all have the same issue. Is there a way to force the hair strands to not subdivide based on camera distance (in case they are). Could you try moving the WONT_RENDER camera forward to see if you can reproduce?

[daniel.kapsazov]

frame48 This is the result I'm getting with the same version of Houdini and V-Ray as you, with the camera moved closer to the hair strands.

I just wanted to confirm that you did try with the latest nightly build, correct?

[frame48]

Just tested out the following version and seems to be working so far! Will let you know if we are able to reproduce the same issue. Thank you.

V-Ray for Houdini number:22733 hash:c018887 from 01 Aug 2024 00:40
V-Ray Core 6.20.20 [92b4ce37] from 30 Jul 2024