Applying opacity map to section of model alters shader look

[stevesideas]

Instead of creating geometry for small holes on a model I often use opacity maps. I have applied an opacity map with a hole texture (black and white) to part of the model and the shader completely changes its look even though every other parameter is setup the same as the shader used for the solid parts of the model.

I've attached a portion of a render to show you what I mean.

[gunny263]

can you also post a screencap of your opacity map settings which show the alpha source?

[stevesideas]

Here you go...

[jacksc02]

is the blacks in your opacity map 100% black? same with the whites?

[LarsSonparsson]

It looks like the reflection ior is changing to 1 when using opacity map.
Afterall, opacity map is working like refraction with ior set to 1.

You could allways do the same with blendmat, right?

[stevesideas]

is the blacks in your opacity map 100% black? same with the whites?

Yep, the blacks and whites are 100%.


It looks like the reflection ior is changing to 1 when using opacity map.
Afterall, opacity map is working like refraction with ior set to 1.

You could allways do the same with blendmat, right?

I've done this before on previous scenes and not had this problem where the shader changes its properties.

Also, even if you were to use a black and white map for refraction it shouldn't change the reflection ior at all.

[DanielBrew]

Could it be a flipped face on the model?

[stevesideas]

hmm.possibly. I'll double check.It shouldn't be though as the faces were just selected from the original mesh and I know for sure the normals are fine on that.

[vlado]

When you use opacity map, V-Ray will automatically assume the refraction IOR of the material is 1.0; this may affect the look of the reflections (there is a very specific and somewhat convoluted reason for this, but we need to do it).

You can solve this by using a Falloff map for the reflections.

Best regards,
Vlado

[stevesideas]

Thanks Vlado. I'll give this a try.