Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: enzodiac on 2014-12-03, 23:06:41

Title: DOF affecting backplate
Post by: enzodiac on 2014-12-03, 23:06:41
I am trying to render a model on shadow catcher material with a backplate as background. However when I turn on DOF everything outside of the shadow catcher gets dof. Even the background. Is this a known bug?
Title: Re: DOF affecting backplate
Post by: romullus on 2014-12-03, 23:45:07
No, it's not a bug, it's a correct behaviour. Although i would like to have control over what amount of blurriness backplate will recieve.
Title: Re: DOF affecting backplate
Post by: Ludvik Koutny on 2014-12-04, 09:58:18
Actually, it could be a bug/ I will have to check if MR does DoF on backplates too. From what i remember, it does not. It does not make sense to add another DoF blurring to the backplate already photographed with DoF.
Title: Re: DOF affecting backplate
Post by: romullus on 2014-12-04, 11:00:16
And what if user has picture with infinite DOF (more often than not, this is the case), or he want to to change amount of DOF? That's way it would be good to have control over what amount of blurriness backplate will receive. Actually, i expressed such wish in feature request a while ago, but it was rejected.
Title: Re: DOF affecting backplate
Post by: enzodiac on 2014-12-04, 11:58:09
I can't really see the use of adding dof from corona to the backplate. That should be handled when photographing the backplate. Anyway the option should be there to turn it off just like we can turn off exposure for the backplates.
Title: Re: DOF affecting backplate
Post by: Ludvik Koutny on 2014-12-04, 13:42:58
I can't really see the use of adding dof from corona to the backplate. That should be handled when photographing the backplate. Anyway the option should be there to turn it off just like we can turn off exposure for the backplates.

Yeah, but there's also case, where backplate is perfectly in focus, yet you want to do DoF shot. In that case, you want backplate  to be blurred. This is quite tricky.
Title: Re: DOF affecting backplate
Post by: pokoy on 2014-12-04, 14:24:49
I can't really see the use of adding dof from corona to the backplate. That should be handled when photographing the backplate. Anyway the option should be there to turn it off just like we can turn off exposure for the backplates.

Yeah, but there's also case, where backplate is perfectly in focus, yet you want to do DoF shot. In that case, you want backplate  to be blurred. This is quite tricky.

Are we talking about viewport/render background or actual mapped plane geometry?

For viewport background, there should be a switch, I agree on that. In case you don't need any dof and want to preview correct dof you actually need a background without any dof added in the render.

If you need dof on the backplate and/or want to exaggerate it you could use a plane and figure what dof fits best by moving towards to or away from the camera.

Also, there should be also a way to exclude ShadowCatcherMtl from dof calculations, only direct visibility, reflections and bump should still render with dof. Not sure if possible, sound tricky, but definitely the way to do it if you want correct resulst.
Title: Re: DOF affecting backplate
Post by: Captain Obvious on 2014-12-04, 15:22:28
It's not a bug, as such. But there does need to be an option for it. Whether you want the background affected by DOF depends on the setup. Sometimes you do, sometimes you don't.
Title: Re: DOF affecting backplate
Post by: enzodiac on 2014-12-04, 16:32:28
Ok i get what you guys are saying. But as stated we do need a switch. Are there any work arounds as of now?
Title: Re: DOF affecting backplate
Post by: Ludvik Koutny on 2014-12-04, 16:53:37
Ok i get what you guys are saying. But as stated we do need a switch. Are there any work arounds as of now?

You can compose it in post. :)