I think this is a real Shadow Catcher problem this time

[treddie]

For those of you who remember my last stupid post , here is what I think is a REAL shadow catcher problem. The attached image is self-explanatory:

[gordonrobb]

Do you have any lights (blackbody or texture) inside the car bay any chance. I had this problem and it was only present when I had an illuminated interior light switched on. Thought it had been fixed though.

[treddie]

Ahhhh, GOOD CATCH! Thank you! The yellow turn signals and the taillights all have very very weak emitter surfaces behind them so that they would not be so dark.
Curiously it is only happening at the front of the car and not the back.

[gordonrobb]

So have you tried disconnecting those emitters? Does that make ther terminator dissapear?

As I said, I thought this had been fixed? What version are you using?

[treddie]

1.53.1, the latest.

Have not had a chance to turn the emitters off yet...Have to finish a render first.

Here is an expanded higher res test of the same problem. It is not as simple as the one diagonal, unfortunately.

This image is with the shadow catcher diffuse surface set to Matte:

[abstrax]

The only thing I can think of would be some self-shadowing (e.g. duplicate geometry) or the emitters. To check you have to switch off all emitters and have the scene illuminated only by the environment. If the matte material is behaving correct now, it's the emitters. If the matte material is still behaving incorrectly, it's either self-shadowing or a bug.

[treddie]

When I get this one render out of the way, I'll test that out and report back.

[treddie]

It is DEFINITELY caused by the emitters!

Thanks to gordonrobb for the tip of the day! Five stars *****

[treddie]

I assumed when first working with the shadow catcher that the gray tone to the catcher surface was normal. So my entire workaround was based on that. Turns out this is a bug. Can there be a fix so that these emitters do not cause this? Otherwise, you have to do two to three passes to get one final image:
1. A shadow catcher render for just the shadows, where any emitters in the subject need to be turned off.
2. A beauty pass for just the subject with its emitters on, w//o shadow catcher on.

If you want the best result, a third pass:
3. A mask image for the subject needed to erase "swelling" of the outline of the subject when the beauty pass is layered over the shadow pass in PShop.

[gordonrobb]

Yup, it's a bug. As I said, fairly sure it was gone, but us now back.