Announcement

Collapse
No announcement yet.

Faster refraction on gpu

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

  • Faster refraction on gpu

    I have been wondering about this for quite some time. Why is rendering refraction so much slower on GPU than CPU?
    In many scenes I feel this is holding GPU back. Everything is faster but the refraction takes ages to refine...

    What are your thoughts about this?

    best regards Nikolaj
    www.nikand.com
    3D Freelance

  • #2
    What V-Ray version and for what host app are you using? Do you have a sample scene?

    Best,
    Blago.
    V-Ray fan.
    Looking busy around GPUs ...
    RTX ON

    Comment


    • #3
      Hi Blago
      I will create a scene for you. I have noticed this from the very beginning of Rt gpu.
      3ds max and vray 35004
      www.nikand.com
      3D Freelance

      Comment


      • #4
        Originally posted by nikand View Post
        Hi Blago
        I will create a scene for you. I have noticed this from the very beginning of Rt gpu.
        3ds max and vray 35004
        Make sure to compare for the same amount of render time, not for the same amount of samples. For the same amount of samples, V-Ray GPU will produce noisier results, it is just that it is expected to calculate samples from camera much faster.

        Best,
        Blago.
        V-Ray fan.
        Looking busy around GPUs ...
        RTX ON

        Comment


        • #5
          okay then here is test with a tv on a wall(solid glass plate in front of tvpanel) . 1m render brute force each.
          Gpu is clean compared to cpu, except for the refraction/caustics. These are noisier on gpu. Click image for larger version

Name:	slowrefraction.jpg
Views:	1
Size:	474.6 KB
ID:	867602

          scene is lit with a single hdri
          www.nikand.com
          3D Freelance

          Comment


          • #6
            Is that V-Ray mtl, or the refraction is part of blend material ?

            Best,
            Blago.
            V-Ray fan.
            Looking busy around GPUs ...
            RTX ON

            Comment


            • #7
              its a vray mat inside a multimat.
              I will try to leave out the multimat to see if there is any difference
              www.nikand.com
              3D Freelance

              Comment


              • #8
                It will not make a difference.
                Can you send the scene to us to debug it ?

                Best,
                Blago.
                V-Ray fan.
                Looking busy around GPUs ...
                RTX ON

                Comment


                • #9
                  I will send it later today Blago
                  /Nikolaj
                  www.nikand.com
                  3D Freelance

                  Comment


                  • #10
                    Seems that I have the same problem in a scene I'm working on now. I found that the reason is the HDRI I use for environment. If I disable the reflections coming from it by using a black color in "Reflection/refraction environement" the problem goes away but the rendered image is not as realistic. Please check the screenshot below. This was rendered for 4 min. on 2 x GTX 980

                    UPDATE: Seems that I get these fireflies with Adv as well so it seems it's not isolated to RT only.
                    UPDATE 2: I put the HDRI in a Vray Dome light instead of the environment slots and the noise is now gone!

                    Click image for larger version

Name:	RT_reflection_noise.jpg
Views:	1
Size:	99.0 KB
ID:	867704
                    Last edited by Alex_M; 07-05-2017, 03:15 PM.
                    Aleksandar Mitov
                    www.renarvisuals.com
                    office@renarvisuals.com

                    3ds Max 2023.2.2 + Vray 7 Hotfix 1
                    AMD Ryzen 9 9950X 16-core
                    96GB DDR5
                    GeForce RTX 3090 24GB + GPU Driver 566.14

                    Comment

                    Working...
                    X