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Fusion 3d Compositing - Rendering Shadow Only


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#1 Alkesh

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Posted 08 December 2013 - 10:55 PM

Hello! Wondering if there is a way to cast shadow of a3D object (including primitives) on to a 3D plane in Fusion, and render ONLY the shadow area, and not the entire plane.

#2 Fresh_Powder

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Posted 09 December 2013 - 04:11 AM

Hi,
Try this comp. "Receives Lighting" unchecked in the Phong works fine for me.
:)

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#3 xmare

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Posted 09 December 2013 - 04:30 AM

or the old compo tricks - make everything white - render out as separate 3D renderer and compo it back into footage...
basically You can have as many override3D / 3D replace materials / 3D renderers as You want, so You can dissect the scene into Your Own "render passes"
:)

#4 Alkesh

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Posted 09 December 2013 - 07:42 AM

Thanks "xmare", "Fresh_Powder". In the file attached ("Shd_Only.comp"), I see that the plane is rendered as white as well. What I am trying to get is just the shadow area, and the rest of the frame to be transparent. I will try xmare method and see if that works. Thanks!

Idea is that I have a live footage. It is tracked in SynthEyes. I need shadow only casted on the road. So, I am making a road in Fusion via a plane. I only need shadow of another object on the road plane,and not the whole plane. I need any part of the road plane that is outside the shadow to be transparent.

#5 xmare

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Posted 09 December 2013 - 08:01 AM

it works :)
just merge it and set the mrg as "multiply" - white areas will be transparent

#6 Dunn

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Posted 09 December 2013 - 08:20 AM

This seems to work too with the "Shd_Only.comp"

Add a ChannelBooleans after the render node & connect both inputs to it
Set the Operation to Subtract
To Red > Red BG
To Green > Green BG
To Blue > Blue BG
To Alpha > Red BG

:)

#7 Alkesh

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Posted 09 December 2013 - 08:21 AM

Got it. Thanks! That's what was missing.




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