Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] General Discussion => Topic started by: jaco graaff on 2015-06-12, 14:17:45

Title: Problem with Shadow Catcher for objects inside a "building"
Post by: jaco graaff on 2015-06-12, 14:17:45

I am rendering a "back plate" of an interior which takes a long time to clean up. Then I need to composite new objects inside the building. The obvious workflow is to render the new objects in a new scene with a matte/shadow-catcher material so as not to re-render the background again...

I have a problem with the render - the walls of the building with a Corona shadow-catch material does not block the sun-light the same way as when a regular material is applied to the "building" - see the picture

see the attached coronaMatte.jpg file

and the Max2016 file in the testMatte.zip archive

Title: Re: Problem with Shadow Catcher for objects inside a "building"
Post by: maru on 2015-06-12, 14:21:52

Can you re-save the scene for Max 15 or older?

Title: Re: Problem with Shadow Catcher for objects inside a "building"
Post by: jaco graaff on 2015-06-12, 15:29:14

saved as 2015

I want to animated various objects in the scene without the need to re-render the interior - the example interior is a simplification of my actual design, but it has the same problem

When the whole building is wrapped in a matte/shadow-catcher material the shadows from the sun are extremely sharp and dark

Title: Re: Problem with Shadow Catcher for objects inside a "building"
Post by: jaco graaff on 2015-06-12, 15:55:10

I included max 2015 scene in the previous post as an attachment - I think this is a limitation of the corona shadow-catcher/matte material

Title: Re: Problem with Shadow Catcher for objects inside a "building"
Post by: maru on 2015-06-12, 16:44:57

I'm not sure if it's possible. The boxes will be affecting the GI on the room, and the room will be affecting the GI on the boxes. There is also sunlight. So if the boxes would cover the windows (or even slightly block sunlight) and you would render boxes+rayswitch only, the sunlight would still be visible in the original "background" image. You would have to render the room with no lighting at all, GI, and boxes separately. I'm not sure if it won't be faster to render the whole beauty pass per frame. :)

(sorry if I don't understand something and I am writing complete nonsense)

Title: Re: Problem with Shadow Catcher for objects inside a "building"
Post by: jaco graaff on 2015-06-15, 01:18:24

Nope it is to simplistic an approach - what will work is if I render the interior as an environment map using the corona camera modifier's "spherical" lens-distortion setting - see the attached image

I then do not have to re-render the whole scene but just the animated small items and composite them on top of the static background

I forgot a bit about this workflow and glad Corona might be able to support it...