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View Full Version : Advice needed on "shadow catching" and render



Turner
10-26-2004, 08:04 PM
Hi -

I'm creating an image in which I need to put an extruded logo on a wall; the logo has to cast shadows, and I'm rendering it with two spots above the logo casting long shadows down the wall and reflected light to fill in the shadowy areas of the logo.

I did it first in another program, with three passes - one alpha for the logo, one with a white wall behind the logo to enable the bounced light to fill in the shadows, and a third with the wall acting as a "shadow catcher" - in the other program, basically, the shadow cast from the logo "reveals" the surface of the wall; I've simply colored the wall black.

The reason for this is so I can fine tune the interaction/density of the shadows on the background.

But.... I'm ashamed to admit that I don't know how to create a shadow catcher in LW.

Any thoughts on how to do this, and possibly how to improve this rendering setup are greatly appreciated!

Cheers,
Andrew

exit6
10-27-2004, 10:27 AM
I'm not sure what you mean exctly, but I often do scenes where I cast a shadow on a ground layer that is transparent, so that when I composite it over a background the shadow is visible but not the ground. If that's what you mean, just throw an object back there to recieve the shadow, give it a black surface called "shadow catcher" or whatever, and in the advanced tab in surface editor change the Alpha mode to "shadow density."

Turner
10-27-2004, 11:03 AM
Thanks!

Actually, I also posted in the Mac forum and got some good response there, including this suggestion, and this is exactly what I did.

Worked! Cheers!
Andrew


I'm not sure what you mean exctly, but I often do scenes where I cast a shadow on a ground layer that is transparent, so that when I composite it over a background the shadow is visible but not the ground. If that's what you mean, just throw an object back there to recieve the shadow, give it a black surface called "shadow catcher" or whatever, and in the advanced tab in surface editor change the Alpha mode to "shadow density."