PNG Decal affects base material

Hello.
Just purchased Rhino 8 and am mostly delighted with it. However I’m having an issue with the Decals.
I’ve created an Asphalt texture for a roof on a tower. When I apply the Decal to the surface it’s causing the texture to go dark. This despite it being a PNG with alpha channel. The colour parts of the decal show but seem way to strong. but the alpha transparent areas are leaving the asphalt dark. The render preview looks fine, so I’m a little lost as to the issue.
Any ideas? Thanks in advance,
Nathan



Hi Nathan - please post a file with that surface with the decal applied, or send to tech@mcneel.com with a link back to this topic in your comments.

-Pascal

Thanks Pascal.
Files attached,
Nathan.
Tower Roof.3dm (1.2 MB)

Hi Nathan - thanks - My Rhino does not like this file at all… I’ll need to dig a little more.

-Pascal

Hi Pascal,
Sorry my bad I uploaded the wrong file, with all the blocks (Railings etc)
Try this one!
Apologies,
Nathan
Tower Roof Surface.3dm (2.9 MB)

Hi Nathan - thanks, that is better, (I still need to look into why the first one is so nasty). I get a different result from you, but still not right - I’ll invesigate.

-Pascal

Thanks,
much appreciated!

@nrtreeves change the material on top of which you apply a decal to PBR, it will look correct.

I don’t know exactly why this happens with custom material - probably related to the alpha channel indeed.

I’ve logged RH-79660 Decal with alpha channel on custom material incorrect base color

Thanks!
I just tried swapping it to PBR and like you said it worked!
The colours still seem a tad strong but for now I can dial that back in the software I used to make the Decal (Affinity).

Many thanks guys,
Nathan.