View Full Version : Rendering Transparent Object on Composited Background

11-08-2006, 03:50 PM
I have a semi transparent object which is sitting on a background image that has been added in the Compositing window.
When I render the scene, my background image does not show through my transparent object.
Any help much appreciated.

11-08-2006, 04:35 PM
You'll eaither have to turn off raytrace transparency and refraction, or put the image on a polygon, backdrop images can't be raytraced -

11-10-2006, 08:15 AM
You could also set it as an image map for refraction in the environment tab of the surface window

11-16-2006, 05:32 AM
I have a similar problem with an object that is composited onto a video. I need the object to disappear behind an object in the video so I created an object for it to hide behind. What do I do to the surface of the 'hide behind' object so it displays the background video and hides the other object behind it? Making the 'hide behind' object transparent just shows the object I'm wanting to hide

11-16-2006, 06:20 AM
karlm, set its surfaces' alpha channel to constant black. It's in the advanced tab on the surface editor.

11-16-2006, 06:24 AM
or was it white? either 0 or 255..

11-16-2006, 09:59 PM
this only effects the alpha image, which would work fine if I was using Adobe Premiere but I'm not. the surface is supposed to show what the background would show so the other object can disappear and all this done through lightwave. thanks for your suggestion anyway.

11-17-2006, 04:08 AM
Use a Front Projection map on the 'hide' object. Project the same video onto it.

11-19-2006, 06:15 PM
It worked, Brilliant. And using 40% luminosity the object is the same shade as the background making it invisible. Thanks for your help.

11-20-2006, 02:24 AM
Doh! Forgot the luminosity. You actually want to turn diffuse off completely, and set luminosity to 100%. That will give you a perfect match.

11-21-2006, 09:10 PM
yeah thanks for that extra bit, 40% luminosity 100% diffuse only works on a flat object, as soon as I made a rotation it stopped working...