Announcement

Collapse
No announcement yet.

Interfering opacity

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

  • Interfering opacity

    Hello,

    First of all, the following example is a simplified version of a real project. The opacity map will be more complex and controlled by other geometry through a VRayDistanceTex.

    I have a setup where I’ve cut an object in half by applying a clipping map to two copies of the same object. Please have a look at the images.

    Image 1:
    Top: Here’s the setup with two boxes, both cut in half with an opacity map.
    Bottom: The problem. When the objects are moved together the transparent surfaces on one object interfere with the opaque surfaces of the other, and vice versa. I realise this is due to overlapping geometry.
    However, please have a look at image 2, showing the same setup in Arnold.

    Image 2:
    The same setup but rendered with Arnold. This is to show that other renderers deal with this differently. I understand there would be a problem with opaque and semi-transparent surfaces interfering with each other, but with full transparency using a opacity map, I would expect it to work like it does with Arnold.

    I would like to do this with VRay though, because Arnold is lacking a lot of nice features that VRay has. And I like VRay.
    Is there someway to make a object's material invisible like in the Arnold example?

  • #2
    You can try increasing the "secondary rays bias" parameter to some small value like 0.001 and see if it helps.

    It's best to avoid overlapping geometry though.

    Best regards,
    Vlado
    I only act like I know everything, Rogers.

    Comment


    • #3
      You can achieve a similar effect with a single object and a VRaySwitchMtl, where an opaque and a transparent shader are plugged with the switch being a ramp texture. Not sure if it will work in your particular project, but it's worth a mention.
      Aleksandar Hadzhiev | chaos.com
      Chaos Support Representative | contact us

      Comment


      • #4
        Hi vlado ,

        Thanks for your reply and the suggestion. I tried the method and it gave me a different result, however it didn't solve the issue. The transparent parts still interfere with the opaque parts, making the opaque parts look kind of semi-transparent. I've attached some renders with different bias settings below.

        Comment


        • #5
          Hi hermit.crab ,

          Thanks for your reply and the tip on using the VRaySwitchMtl. I tried it out, and it works pretty much as my original setup where I used a VRayBlendMtl. And in regards to my issue with transparent parts interfering with opaque parts, it gives the exact same result as previous images I attached. Below are the setups, just to make sure I've done it correctly:

          Comment


          • #6
            Yes, the setup is correct. However, the workaround was meant to bypass any overlapping of objects.
            Aleksandar Hadzhiev | chaos.com
            Chaos Support Representative | contact us

            Comment

            Working...
            X