CGTalk - Problem with the Matte Material and Compositing.

View Full Version : Problem with the Matte Material and Compositing.

RockinAkin

01-30-2003, 11:28 PM

Alright...

I'm setting up an animation, where a character will walk into an environment in front of a non moving camera. I've created and rendered the environment from the stationary camera
(which took about 1.5 hours to render cause of GI, which is obviously too long to create an animation with frame by frame.)

So I want to composite the animation of the character onto the image of the environment I've rendered out.

So, now... in MAX, I assign the Matte Matterial onto everything in the environment scene (this will prevent the environment from being rendered, but still allow for it to receive shadows cast by the character).

My problem is that the environment casts shadows onto itself... which slows down the matte render almost as much as if I rendered it out regularly.

I'm trying to make it so ONLY the character casts shadows onto environment, and the environment casts shadows onto the character. The environment can NOT cast shadows onto itself.

Hope you understood that.
-DivideByZero-

phil

01-31-2003, 12:40 AM

that's a nasty little prob.
The only way I can see to get around it would be to do 2 shadow passes. 1 where the character casts a shadow on the environment but the environment casts no shadows. The other pass would be the opposite - the environment casts shadows but does not recieve while the character recieves shadows but does not cast them. Then comp these 2 passes together.
make sense?

might be an easier way but i can't think of one off the top of my head.
cheers:beer:

E.T

01-31-2003, 10:09 AM

im going to do this pretty soon too, so i also want to know this.:wavey:

RockinAkin

01-31-2003, 05:42 PM

I tried the 2-pass shadow idea, and it didn't work well... it still takes unusually long.

The only solution I can think of is to have a MAXScript in which we can select an object's properties, then have an Include/Exclude button for the Cast and Recieve Shadow properties, that works on the object level.

This way, we could select the environment with the matte material, and tell it to only recieve shadows from the character object... and only cast shadows onto the character object.

Now, anyone know how to program that?

-DivideByZero-

Antilles

02-01-2003, 04:10 AM

forgive me if i sound uninformed or something but phils solution should have worked...its sad that it takes a long time to render each pass, but oh well. Would using that maxscript thingy really make it faster? Doesnt it still have to calculate all those shadows anyway?

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