Rendering with composites???

I’ve already got the 3d inserted into the video. (I motion tracked using Icarus and imported the video as a background in blender, and then inserted the cgi in the appropriate places) Now, what would be the best way to render?? When I tried, (Though I have no idea what I’m doing)all I say in the render window was a black square (in the same place it is in the video) against a blue background. Can someone please tell me the proper way to render??

In the Buttons Window go to Scenes (F10). In the render tab use Premul instead of sky, In the Anim tab press Do Composite, and make sure that in the Format tab all the settings there are the same as your source video. Go into the Node editor and click on the Composite Nodes button and then Use Nodes. Add an image( spacebar > input > add > image) and click the up and down arrows and load your video. You might have to manually set how many frames there are but you can just set it to a ridiculously high number that will cover it. Also click on the icon on the bottom right of the node that looks like a car. Add an Alphaover Node ( spacebar > add > color > alphaover). Attach your source video to the top image input on the alphaover node and attach your rendered layer to the bottom one. Attach the alphaover node to the composite node and that should do it.
Hope that covers it.

For some reason, it won’t allow me to attach the top image input of the alphaover node to the source video.

Nevermind. Thanks BFish. Is this how they render all composites??

There are a few other ways you CAN do it but to answer you question, yes, this is how it’s done. :smiley: