Take the HP commercial for example, the guy which is singing and "taking pictures" by holding a white frame in front of his head. (It is shown here in the Netherlands...).
They use the high contrast of the frame to determin the perspective and size of the frame contents. Maya can do this (just like the software that has been mentioned).
At the moment the guy holds the frame in front of his head and moves it away, a "snapshot" of the guy is rendered inside the frame and it looks like it has become a photo.
A simple concept, but amazingly well done.
For movies like Lord of the Rings, "motion track cameras" (I dont know the exact name) are used. They "save" the position of the camera, and when you pan the camera in X,Y,Z, the coordinates are saved. When connected to equipment like a crane, the crane then later can playback the exact movement that has been recorded earlier.
Even better, the X,Y,Z data can be important by a 3D application (3dmax, Maya, ...) which exactly matches the viewport perspective, FOV etc.
In the end the 3D is placed on top of the movie as a layer. During modelling the movie is used as a background. I think the real hard thing is to match the light of the 3D models with the actual movie footage.
They use the high contrast of the frame to determin the perspective and size of the frame contents. Maya can do this (just like the software that has been mentioned).
At the moment the guy holds the frame in front of his head and moves it away, a "snapshot" of the guy is rendered inside the frame and it looks like it has become a photo.
A simple concept, but amazingly well done.
For movies like Lord of the Rings, "motion track cameras" (I dont know the exact name) are used. They "save" the position of the camera, and when you pan the camera in X,Y,Z, the coordinates are saved. When connected to equipment like a crane, the crane then later can playback the exact movement that has been recorded earlier.
Even better, the X,Y,Z data can be important by a 3D application (3dmax, Maya, ...) which exactly matches the viewport perspective, FOV etc.
In the end the 3D is placed on top of the movie as a layer. During modelling the movie is used as a background. I think the real hard thing is to match the light of the 3D models with the actual movie footage.