V-Ray Rectangle Light Randomly Changing Shape/Size (Rhino 7 & 8)

Hi everyone,

I’m hoping someone might have come across this before because it’s causing a significant amount of rework on my projects.

I frequently use V-Ray Rectangle Lights to simulate concealed LED strip lighting in my Rhino models. Quite often, after creating the lights, changing the Kelvin colour temperature seems to randomly alter the size and shape of the rectangle light. It doesn’t happen every time, which makes it very difficult to isolate.

What’s even more frustrating is that sometimes I haven’t edited the light at all. I’ll reopen a file and find that several (or all) of the rectangle lights have changed dimensions or proportions completely. Because they no longer align with the LED recesses they were created for, I end up having to recreate them from scratch.

I’ve tried to identify a pattern, but so far there doesn’t seem to be any consistent trigger. The issue appears to happen randomly.

Some additional information:

  • Rhino 8 (currently)
  • V-Ray for Rhino (latest version)
  • The same issue also occurred in Rhino 7.
  • The lights are generally long, thin Rectangle Lights used to represent LED strip lighting integrated into cabinetry and interior detailing.

Has anyone experienced this behaviour, or is this a known issue? Is there a setting, workflow, or bug that could be causing the rectangle light geometry to change unexpectedly?

Any suggestions would be greatly appreciated, as this has become a recurring problem in my workflow.

Thanks in advance.

Hello @kitto ,

Thank you for your report.

I haven’t been able to reproduce the issue on my end so far. Would it be possible to send us a scene or a simplified version of it? This can help us reproduce and identify the issue. You can do this by packing the scene (V-Ray menu > Pack Project) and attaching the archive directly here or via a support request. Please make sure to mention this forum thread in your support request so we can easily link the files back to your query!

Thank you in advance!

Kind regards,
Iva