Compositing EIAS renders into live action footage

[apu]

Hi

I have a live action footage of a bar. I tracked the camera with PFTRack and imported the camera movement into EIAS. I want to render some beer bottles and composite it into the live action footage for product placement. The problem is that I have some beer bottles and I placed them on top of a plane model that acts as the table where I am going to cast the shadows into. If I turn GI on, I can't get a shadow mask of the plane. How can I isolate the shadows so I can composite it into the live footage?. Cause I need the GI illumination to get the feeling that the bottles are "touching" the table. I need realistic shadows. I turned on raytrace softshadows with GI optimization on, because if not, the render times are too long.

Any suggestions?. Other times, what I did is to render two passes, one of the whole scene, and the other one of the alfa channel of the bottle. What I did then is composite the whole scene render with multiply layer mode (this works if the plane acting as table/floor is white), and then on top the same image with the alfa of the model.

But as I said, this only works if the plane is withe, and the illumination is with based. But in this case, I have neon lights, red, lights, green lights, etc....

Please, help, I'm desperate!!!!!

[Ian]

I'll look into this, getting the GI out is easy (do an occlusion pass) - getting the colour bleeding out is not so easy... You can't even do that with Vray. I will do a few test tonight.

Ian

[Arketype]

Hi Apu,

This is easy if you use the Layers feature.

In the layers tab add the layers shader to "all objects" and edit it's settings

to produce a "final render" with layer mode set to multiply.

Also create a selection set of all objects, but exclude your shadow plane.

Add this selection set to the Layers tab, and add the layers shader.

This should also be set to "final render" but the layer mode should be "normal.

This technique works very well with still images.

I have been meaning to do a quick tutorial video of this ;)

I have not tried it with animation, so hopefully sequential PSD files won't be a problem.

Let us know how it works for you.

Dave

[Ian]

Okay I did some tests, and you can't do this with 'generate shadow mask' but, as Dave says, you CAN do this with a layer mask and the Ambient/GI layer.

You could of course do the layer manually by setting your ground plane to black and you objects to shadow only, then 'add' that back onto your composite.

I've attached a sample project if you want to take a look.

Ian

bleeding.prj.zip