Thursday, 6 January 2011

ALAN/JON. Tree Issue

Hey Alan or Jon,

Can you explain how the tree matte pass is going to work on when I come to rendering and then comping? I'm slightly confused.

When I come to rendering the trees, I render off a colour pass with the surrounding environment black holed but the trees on a coloured surface shader. I then render a pass where the environment/structures etc is on a black surface shader and the trees on a white surface shader to simulate an alpha channel.

How in After Effects do I make the black and white pass the alpha channel?.


Jon Stewart said...

You want to render the trees on a seperate render pass? You can use a render layer, and apply ' use background shader ' to everything in the scene except the trees. If you render as Tiff it should then have an alpha channel built into the file. Which you can then use as a transparency in Premiere.

Tom Beg said...

But the alpha channel for the trees are square because I've used a transparent image plane, its not the shape of the tree. Or by doing it with your method would it keep the shape of the tree for the alpha channel?

If it was the shape of the tree, then it'd be plain sailing :(.

Tom Beg said...

No wait! just tried rendering the trees on a different layer and the alpha channel is the correct shape!

I've just had stupid panic attack.

Jon Stewart said...

Yeah, was going to say. You still render the trees with the correct texture / transparency. You just render everything else with use background shader.

Tom Beg said...

Yep, there's a lot of methods I can use. Going with a mixture of render layers and black holes. Got a few last minute jitters I think. :/

Alan Postings said...

Indeed Tom, Try and stay calm.