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View Full Version : Shadow catcher node shows up in renders?



Spinland
01-28-2013, 08:20 AM
Not sure what I'm doing wrong, I expect it's simple. I have a background image projected onto some geometry, and the character standing on a ground plane with the shadow catcher node applied. In VPR and in renders the ground plane looks like it obscures the background and is showing the Image World lighting image instead of being invisible so the background can show through. Radiosity is enabled but turning it off didn't seem to change anything.

Attached is a sample render and a screen shot of how i have the ground plane nodes set up. Can someone help steer me towards how to make this work as I intended?

Many thanks in advance!

110734

110735

RebelHill
01-28-2013, 08:58 AM
set reflection to 0 in catcher node.

Spinland
01-28-2013, 09:10 AM
Thanks. I just tried that per your suggestion (screen shot attached) but it didn't seem to have any effect at all. It's almost as though the ground plane is making the back plane beyond it transparent rather than it's reflecting the environment. Is there some kind of z buffer ordering or something that might apply or is that completely off base?

Thanks again!

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Spinland
01-28-2013, 11:00 AM
Okay, re-reading the docs on Shadow Catcher and I can see I misunderstood something. You still have to have a background image defined in the compositing window, as that's what the Catcher gets its color from--so it still seems like a front projection in that regard.

The problem I have, then, is I didn't want to use a BG image like that. I want a little bit of camera pan and with a BG image it would stay static no matter how the camera moved--that's why I projected the BG onto geometry instead and I thought the Shadow Catcher would just let that show through with shadow added.

So it seems the Shadow Catcher node is only really useful for static images? How do folks get around needing some camera movement when using both a shadowed ground plane and a background image?

Thanks in advance!

dwburman
01-28-2013, 11:12 AM
You could prerender the camera move with just the background and use the resulting image sequence in the compositing tab.

Spinland
01-28-2013, 11:16 AM
Excellent idea, thanks!

RebelHill
01-28-2013, 11:52 AM
Okay, re-reading the docs on Shadow Catcher and I can see I misunderstood something. You still have to have a background image defined in the compositing window, as that's what the Catcher gets its color from--so it still seems like a front projection in that regard.

The problem I have, then, is I didn't want to use a BG image like that. I want a little bit of camera pan and with a BG image it would stay static no matter how the camera moved--that's why I projected the BG onto geometry instead and I thought the Shadow Catcher would just let that show through with shadow added.

So it seems the Shadow Catcher node is only really useful for static images? How do folks get around needing some camera movement when using both a shadowed ground plane and a background image?

Thanks in advance!

Aha... yeah that explains it... I thought u were jsut picking up a reflection from enviro and that u had static BG. DWs solution works fine... but its more common that this gets used without any BG image in LW at all (unless a simple static setup) and the results used in a compositing package.

Spinland
01-28-2013, 12:36 PM
Cool. That all makes sense, thanks. I need to get more comfortable with compositing, that's for certain.

In the meantime I sidestepped the issue: I just Photoshopped the shore area out of the image entirely and built it as geometry. ;)

Thanks again, guys!

Eagle66
01-30-2013, 01:33 PM
Another quick question: does the Shadow Catcher node work correct with radiosity (GI) - image based lighting?