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View Full Version : Merging render into photo/background

joost_db
11-14-2007, 06:54 PM
I am trying to render out an object so that the plane it is sitting on will blend perfectly into the background color of a webpage. I.e. so that that plane the object is sitting on is a #33333 grey, and that there is a seamless transition to the #333333 webpage.

Adding lights etc will change the color of the floor, i am only wanting a bit of shadowing and ambient occlusion underneath the object.

How is this best done? I am guessing somehow in post, rendering the shadow pass seperatly in black&white and then using a multiply blend mode in PS layering it onto #333333 color? Then dropping the aplha channeled object ontop??
metal0130
11-14-2007, 11:23 PM
im not sure exactly what you are doing? you want an image with transparent shadows so you can see the background through the shadows?

what about applying a "use background" shader onto the ground plane and rendering it out with a mask. the shadows will be transparent in the alpha map, and so as long as you are saving it to an appropriate file format, the alpha will be preserved and the shadows will be transparent in the final image...

render the object all alone sitting on a plane (plane textured with use background shader - no reflectivity, no reflective samples or whatever... all sliders down except shadow mask left at 1. the color channels will only have the object and transparent shadows... alpha will have object in white, transparent shadows and black background.
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11-14-2007, 11:23 PM
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