Artefacts in old scene - Material support problem?

[Eszter Kallai]

Hi,

I was reopening one of my older scene I've made in March and got strange artefacts in latest daily build when rendering it. (I'm using the build from 05.09.2017).
You will find a reduced scene in the attachment.
I've had no more time to figure out what exactly is causing it but you might have an idea when you open the scene. This used to render fine.

[TomG]

Downloaded the scene and rendered in R19 and R18, Corona daily build Sep 5th, result is attached - I believe this is the correct result without artefacts? I swapped it from a C4D material to a Corona one after that, and it still rendered fine too.

Does this happen every time you render? Anything else that may be different from my test, for example, were you using Team Render?

[Eszter Kallai]

Hi TomG,

no I haven't use Teamrender.
sorry for not getting back to you earlier. I just remember posting this bug since I came across with a similar effect in a new scene.

I've checked the render_artefacts scene again and actually the new PBR materials (introduced in R19) is causing the problem I think.
I attach a new scene where you have a single material with 2 reflectance channels. The top one shows the correct look on the render (see on the below image). The one below results to a broken look.
Since I see no difference between these two channels on the GUI, there must be something internally which is off.

You can reproduce the same from scratch if you open a new cinema scene and go to Create > New PBR material on Material Manager and assign this material to an object in the scene then render with Corona.