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Object with transparency channel on a Vray Material flickers and look smeared/blurry every few frames

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  • Object with transparency channel on a Vray Material flickers and look smeared/blurry every few frames

    I'm rendering an effect made of a rig in Maya that scales up and translates some texture UV on a "+" shape piece of geometry that is 2 single polygon squares merged with each other that scale forward to simulate a smoke trail from a projectile in a video game. The texture applied is a standard Vray Material with solid white diffuse color and a smoke texture applied as the opacity map. It's rendered from an animated camera that is changing focal length mid-shot, and every few frames it seems to flicker in a strange way where the texture gets smeared. It happens at the same frames every time I render via command line, and even when rendering the sequence from within maya.

    I've tried even using a simple ramp shader as the transparency texture and it still happens. I've also tried applying it to a double-side shader, and swapping the Vray Material node for a Vray Light Shader, but nothing seems to work. I've attached a comparison picture of the same frames with both types of textures on a flickering and non-flickering frame.

    The strange thing is that it doesn't seem to happen in the Vray VFB if I start on a non-flickering frame and then switch to a flickering one while it's in the middle of rendering.

    I'm using the GPU rendering in Maya 2023 and Vray 6 for Maya v6.00.02 from Aug 30 2022.

    Any help would be appreciated.

    Edit: I have also noticed the same flickering on a similar effect render using ramp textures and alpha channels, to look like a laser beam, on another shot, but one where the camera does not have an animated focal length.
    Last edited by chris_dike; 03-11-2024, 10:38 PM.

  • #2
    Mind if you send the scene so we can troubleshoot?
    Aleksandar Hadzhiev | chaos.com
    Chaos Support Representative | contact us

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    • #3
      Originally posted by hermit.crab View Post
      Mind if you send the scene so we can troubleshoot?
      Here's the archived scene. I also filled out the ticket request form in the links.
      https://drive.google.com/file/d/1iJb...ew?usp=sharing

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      • #4
        Thanks. Will report back after I've finished troubleshooting.
        Aleksandar Hadzhiev | chaos.com
        Chaos Support Representative | contact us

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        • #5
          I managed to reproduce the issue on a simple scene. It seems that transparency-mapped objects, scaled with large values produce artifacts. This happens in a very simple scene as well. I've logged it for dev investigation (internal bug-tracker id: VGPU-6652). It does happen quite randomly so I'm not sure if there's a simple workaround. I suggest you render your whole animation, locate the bad frames, and re-render them in CPU.
          Aleksandar Hadzhiev | chaos.com
          Chaos Support Representative | contact us

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