Announcement

Collapse
No announcement yet.

Image rendering differences with Vray 6 update 2 and PhoenixFD when switching from CPU to CUDA/RTX

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Image rendering differences with Vray 6 update 2 and PhoenixFD when switching from CPU to CUDA/RTX

    Hi all,
    I have two questions regarding issues I'm facing when switching to Vray GPU.
    I was testing Vray GPU vs CPU in a personal test scene made for fun (think of it as a futuristic submarine emerging in a stormy sea night).

    QUESTION 1, IMAGE TOP ROW: as you can see, rendering the exact same frame the PhoenixFD sea surface seems to shift or displace differently, also the water on the top of the "ship" looks noisier/bigger/fatter. It looks like a cache frame offset/shift too. Differences are subtle but visible (see the sea surface in the lower right corner, or the splashes and sea surface at the center of image below the ship window, or the splashes at the left side of image).

    QUESTION 2, IMAGE BOTTOM ROW: the Chaos doc for Vray says "The supported features of V-Ray GPU running on CUDA and RTX are the same. Although CUDA and RTX share the same user interface as the V-Ray engine, V-Ray GPU differs from the regular V-Ray engine in the way it performs certain calculations". But as you can see, when switching from CUDA to RTX, the background part of image is different (in this scene I use EnvFog with Box gizmo).Fog seems to be present only in the top of picture, but no more on the center section of scene.​

    I'm on Vray 6 update 2 and 3ds max 2024.2; PFD cache is on UNC path; no error messages reported. I didn't change anything in the scene, only the render engine. Render times are quite different: CPU 2':45", GPU CUDA 0':39".
    System: win 11, i9 13900kf, 64GB ram, RTX 4080, nvidia drivers 546.01 .

    Thank you to all who'll may provide some advice.
    Last edited by ilmelovfx; 03-12-2023, 04:47 PM.

  • #2
    EDIT: Referring to Q1​, I rendered an 82 frames long animation (from 0 to 81) and the differences are evident (see attached video). I also compared frame by frame the animation, looking for frame offset/shifting, but I can exlude this is the problem.
    I'm sorry but forum tells me I'm not allowed to post or attach MP4 files.
    Last edited by ilmelovfx; 03-12-2023, 05:46 PM.

    Comment


    • #3
      From Georgi Zechov of Phoenix developers team who answered in the Facebook Phoenix group (thank you Georgi):

      "...For the first one - the vector displacement that is used for the Ocean texture is not working properly with V-Ray GPU - it's already in our bug tracking system.

      As for the black part of the image - really have no idea. Can you send over the scene through the support system and we will take a look? You can send it over from here - support.chaos.com (there is a Submit a request button at top right)."

      I've sent the max file.


      Last edited by ilmelovfx; 05-12-2023, 02:44 PM.

      Comment

      Working...
      X