Vray Decal Gradient ramp opacity issue

[stevesideas]

I am using a vray decal. I have imported a map from Quixel Bridge. One of the mud splats.

I am trying to graduate the opacity using a gradient ramp but it only delivers a harsh cut of the decal...not a gradual reduction to zero opacity. Any ideas where I am going wrong?

[vladimir_krastev]

Hi, it seems to work in a simple scene.

Could you share a bit more detail about your application? It will be best if you use screengrabs or a scene to illustrate your workflow.

[stevesideas]

Sure. I have a decal placed over the side of a vehicle as shown in the image. I've then applied a gradient ramp as a composite blend to the opacity texture with a black vray colour layer below in the composite.



Which outputs this preview



On the rendered car though there is a harsh line...almost like the gradient is in solid mode and there is no interpolation between the shades.

[stevesideas]

So, I tried a standard Vray material. I thought it might be the vrayscanned material that was causing this issue. It wasn't.

The gradient black is 0,0,0 rgb. It just will not fade to black (zero opacity).

[stevesideas]

So, if I apply just a vraymaterial to the object underneath it works fine. If I have a vrayblend with the same material at 100% opacity but the original vrayscan on the layer underneath, the problem persists..albeit it becomes less noticable.

[stevesideas]

Right. I worked it out. It was because I was using cryptomatte in the VFB for the door paint...it was screwing around the the opacity threshold. Now that I've included the vraydecal into the same set of curves/cryptomattes it looks fine.