imageplane projection on object issue

# 1 29-11-2006 , 11:43 AM

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Join Date: May 2006

Posts: 79

Hi Guys!

Got a maybe small problem here...

I try to explain it with a test scene...

I want to have a object laying on the street, but on a image street. No Prob so far. as u can see:

I modeled the scene (just the shape, not very detailed here)

user added image

... Then Ive put a projection of the image over this scene in the back.

user added image

My problem is now, that I want to keep the image but only with the shadow of the object (the cube) I want to render (later a car) ...

Maybe some can help me with that?

Greeds S3rj

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# 2 29-11-2006 , 12:04 PM

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Join Date: Jun 2004

Location: Cleveland, Ohio (USA)

Posts: 1,542

you want to use a 'use background' shader on where you want the shadow to fall... it will only render out where the shadow of your object is (alpha included), which is perfect for compositing.

edit: i would recommend creating a 'faked' scene (objects that stand in where the building, street, and sidewalk would be... looks like you've already got them) and put the 'use background' shader on that. then you can composite your car and shadow over top of your original image.

Accept no substitutions.

Last edited by NeoStrider; 29-11-2006 at 12:06 PM.

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# 3 01-12-2006 , 08:45 AM

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Join Date: May 2006

Posts: 79

okay thats a way, but I know from cinema4d thats possible to tell the object, to throw a shadow on the imageplane, without doing a second rendering...

this must be also possible with maya! ... I hope so ^^

otherwise thx for ur option!

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# 4 01-12-2006 , 09:00 AM

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Join Date: May 2005

Location: Manchester Uk

Posts: 6,300

Can you not just render a shadow pass in the render layers option? Or am I missing the point?

"No pressure, no diamonds" Thomas Carlyle

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# 5 04-12-2006 , 10:17 PM

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Join Date: Oct 2002

Location: London, UK

Posts: 2,800

It's a better solution to render as two passes and comp them togther afterwards. e.g.

you render your shadow as one pass as in cinema4d. Lets say you want to change the shadow colour without re-rendering everything. You will have fun roto-ing the shadow user added image