View Full Version : Image compositing

11-26-2005, 03:02 PM
Hello.....kind of a new here...especially with compositing....not sure if anyone watches HBO..they currently run a commercial for their series where they have the name of the series show up in some of the shots for Rome, Curb Your Enthusiasm etc....so I grabbed a pic of some penguins and just want to comp in the word penguins....was wondering if there is a tut or someone can give me a quick idea on it...

What I have done so far is added the image as the background and matched the camera angle pretty well....the problem is that I added a plane to recieve my shadow and added the image as a front projection on the plane....but you can clearly see the plane......

How much harder does this get with video..and if you want to comp the 3d element behind portion of the video too?

thanks for any help.

11-26-2005, 03:53 PM
Normally, I would render out the 3d type that you made on black with an alpha channel. Then, I would render out the shadow by itself. Next, I would composite it onto the background using a compositing program like After Effects. This way, you have more control over the individual elements and you can tweak them. Also, you can make your 3d object appear behind things in the live-action by creating masks.

It can get more complicated when using moving video, especially if the camera is moving. Then, you need to track your elements to the movement of the camera.

11-26-2005, 03:59 PM
Little tip, in surface options "alpha: shadow density"

11-26-2005, 05:17 PM
The plane should have diffuse turned off and luminosity set to 100%. Then the front projection will match perfectly. Of course then your shadow won't show up, which brings you back to what Axis was saying about rendering it separately. And to do that you'll need what Walfridson mentioned, the shadow density option in the plane's surface.

11-26-2005, 06:54 PM
You can also use this simple technique. Use frontprojection on the plane with 100% luminosity and 100% diffuse. Clone your light that cast shadows and set it -100% and turn off shadows and exclude all objects but the plane. Ready.

Here's a test I did with LW, no comp.