Disable DOF calculations for objects backplates/geometry with ShadowCatcherMtl

[pokoy]

I am rendering content over photographs screen mapped to geometry with the ShadowCatcherMtl and they all have DOF which I'm trying to match in the rendering. Unfortunately, Corona's DOF will add defocus blurring on the shadow catcher geometry and it's too extreme. I can composite the rendered content over the original backplate in post, but in places with more extreme DOF it will not blend correctly as I still have doubled DOF in places where the alpha is not completely black or white...
I am trying to get a solution for this but it seems the only working way would be to exclude that screen mapped geometry from DOF calculations. Would something like this be possible at all?

[maru]

I think this may be impossible as DoF in Corona is "physical". It's hard to imagine for me to have some objects affected by DoF, and some not.

[pokoy]

I think this may be impossible as DoF in Corona is "physical". It's hard to imagine for me to have some objects affected by DoF, and some not.

Yes, since it's even impossible in any of the ray tracers I already had my doubts.

[Ludvik Koutny]

On the one side, not even Vray can do it, let alone mental ray. On the other side applying DoF to already blurred plate kinda breaks correct compositing, so option no to do that would be useful.

[pokoy]

On the one side, not even Vray can do it, let alone mental ray. On the other side applying DoF to already blurred plate kinda breaks correct compositing, so option no to do that would be useful.

If possible, having that would be fantastic. What if ShadowCatcher would be 'transparent' and would multiply over the directly visible background override? I think that should be possible somehow.

[Ludvik Koutny]

On the one side, not even Vray can do it, let alone mental ray. On the other side applying DoF to already blurred plate kinda breaks correct compositing, so option no to do that would be useful.

If possible, having that would be fantastic. What if ShadowCatcher would be 'transparent' and would multiply over the directly visible background override? I think that should be possible somehow.

I thought something similar. Will ask Ondra about that.

[pokoy]

Great, thanks!

[Ludvik Koutny]

Great, thanks!

Ondra told me it should be possible. Practical implementation would probably be a checkbox in ShadowCatcher material. So fingers are crossed.

[Ondra]

long story short: probably possible for screen mapping

[pokoy]

Great, glad to hear that!

[Ondra]

note to self: will be probably best if added to CoronaBitmap instead of shadowcatcher

[maru]

to self: btw ticket 477

[pokoy]

Bumping the thread to ask if this is on the horizon. It would make working with photographed plates a lot easier.

[pokoy]

And another bump to see if it's possible for 1.5 - I am fighting with this problem in every other project since we often work with backplates and many of them have strong DOF. It would make life really easier in those cases.

[Ondra]

well... maybe ;) I would like to focus more on smaller requests such as these in 1.5