Issues with transparent PNG images using the old diffuse layer

[matthewg]

Sorry about the long title, not sure how else i could have worded it.

Please excuse me if i get any terminology incorrect as i just handle the IT i am not a designer myself.

One of our designers send this message through to me.

"Ive found a potential issue with the new vray! We tend to work a lot with png files for products in our models, the new vray has made it a bit more complex to use a png as a transparent file. The material needs to have a VrayBRDF layer in which you can adjust the opacity values (as attached)

If you don't do this the png has will render with a white background!! It might mean product made in older versions wont render clear if the settings aren't first adjusted. If the material doesn't already have a BRDF layer then it means reimporting and scaling the texture!"

The renders shes shown me this happening on are clothing items. I believe what shes asking is there an easier way of converting the opacity from the old diffuse Layer option to a new VrayBRDF layer without having to recreate it.

Regards

Matt

[matthewg]

Attachment that was sent with the query sent to me

[Peter.Chaushev]

Hello, Matt,

If recreating a material is not an option, simply keep it as it is, open the old Diffuse layer and enable the layer's Advanced Options > "Diffuse Map Alpha as Transparency" option.

Kind regards,
Peter

[sigrid]

Hello! I've had the same issue yesterday...
It took me a while to figure out that even creating a new material and putting it on the surface wasn't enough, it still would render white. Even using an alpha map in a new materials didn't work when the texture was applied onto an "old" surface.
Once I succeeded in making the background transparent but then the shadows would still turn up as a rectangle instead of the three shadow.

The only thing that seemed to help was:
- deleting all objects using the png
- deleting the now "unused" texture
- adding the png as a new material into the model
- REDRAWING the surface on which the PNG is needed
- Apply and scale the NEW material on the NEW surface.

This is a hell of a lot of work to do for all library models... So it would be great if this bug could be fixed...

[matthewg]

That's fantastic Peter,

Simple answer for a simple question

I think what was happening is they tried the Diffuse Map Alpha as Transparency box but were not being patient enough for the preview to update so were ticking it back on again. (we had to disable it to get the result we wanted)

Thanks a lot for your help once again Peter.

Regards

Matt

[Peter.Chaushev]

Hello, Sigrid,

Have you applied different materials to the front and back faces of these objects?
Could you please save the scene (Extensions > V-Ray > Pack Project) and share it either here or by email addressed to support@chaosgroup.com ?

Kind regards,
Peter

[sigrid]

Hi Peter,

The materials should be the same front and back. This is is a model I use for simple backgrounds when rendering an interior view (I know it looks quiet silly but it does the trick).

I just imported the model from the one I used in 2.0. I'll e-mail it since the packed project is too big for upload.

Many thanks!

Sigrid

[Peter.Chaushev]

Thank you for providing the sample scene!
To fix your problem, simply open each material's Bitmap texture and set Color Space to "Screen Space (sRGB)" and then disable the Diffuse Layer's Advanced Options > Linear Workflow checkbox. (Functionality limited in GPU render mode.)
Alternatively, you can recreate the materials manually using V-Ray Generic materials as template.

Kind regards,
Peter