if you cant basically draw on a vdeo to put cgi in it but have to develop the model and animations then import it composit whatever it into the video how are you supposed to know where your putting the actions and such
Pre-production! Having a clear idea of what you want the shot to look like and the action that will take place before you shoot is the key. Story-boards, written descriptions, things like that.
Also, a 3D model is only going to show up where the model is. In other words, you can see the video under the model, so you can SEE where to place it.
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