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View Full Version : Refractive/Transparent geo not seeing background ?



SaturnX
06-08-2012, 09:47 AM
I might be having a brain fart here.
I have a 3D motion tracked scene, involving animated glass geometry on top of a video plate. My transparent geometry is not seeing the backdrop imagery inside layout. Both texture layers and node shaders don't see the background. Am I missing something silly?

Tobian
06-08-2012, 11:09 AM
The background plate does not actually exist in the scene, it's simply composited into the render. To get it to show up inside the render of complex objects, create a large polygon, place it behind the object set it to diffuse 0 and luminosity 100 (and everything else off) plug in your texture, to colour, and change the mapping type to 'front' which will project it to fit the display. This way the backplate will physically exist in the scene. Remember however that nothing exists outside of it, so for the POV or refraction or reflection, they see more than just the background, so you may need to also create an environment which matches the backplate.

Sensei
06-08-2012, 03:01 PM
Nevermind. I understood question incorrectly..

SaturnX
06-13-2012, 07:30 AM
The background plate does not actually exist in the scene, it's simply composited into the render. To get it to show up inside the render of complex objects, create a large polygon, place it behind the object set it to diffuse 0 and luminosity 100 (and everything else off) plug in your texture, to colour, and change the mapping type to 'front' which will project it to fit the display. This way the backplate will physically exist in the scene. Remember however that nothing exists outside of it, so for the POV or refraction or reflection, they see more than just the background, so you may need to also create an environment which matches the backplate.

Thanks for the response.
It turns out it was the refractive index and the geometry that was the problem. I had to simplify the glass geometry I was using. the refractive qualities when set to anything higher tan 1.1 was causing series opacity problems for some reason.
I'm just after coming off the back of a small project in Maya, involving dialectric glass objects etc and had tried similar modeling methods in LW.

It's seeing the backdrop ok now after simplfying the geometry in LW.

As for the environment, I have a base HDR setup complete with reflection maps. It's been the refraction and geometry that's been not playng ball however.

suzaku
08-04-2012, 03:14 PM
I have a related issue; I have a glass geometry in the scene and a video backdrop (my scene is also a motion tracking exported into Layout). I've set reflection and refraction values and everything looks great, but when I render a .png image, the refraction doesn't appear though it does in VPR or .jpg renders.

I also have a plane with the shadow catcher node applied and it doesn't appear refracted in .png renders