The Technical term for this is “Match Moving”. Its a technique used though-out the world in the Visual Effects industry to insert computer generated graphics into live action footage. When it’s done correctly it will look absolutely seamless and real and will fool even the most Wily of us.
Thing you will need;
A Camera – preferably a good quality video camera.
Some 3D Software – Don’t worry they are not all thousands of pounds to purchase. Software such as Maya, Cinema 4D and 3D Studio Max can be very expensive, though Blender is free and there a literally thousands of tutorials on the web to get you truly up and running.
So how is it done?
The first thing we need to do is take our footage shot on our camera and track it so we can create an “identical” camera that is virtual, it sits in our 3D program. So when you add our 3D elements they will appear to fit into the footage perfectly, as the perspective matches exactly.
The way this is done is call tracking. We need to identify some features of the footage that may stand out. For example; corners of doors, areas of high contrast, black and white spots (some 3D programs even do this automatically). Once these have been selected the 3D program will then scan the footage following these points you have selected and create a virtual camera that matches your “real” camera movements exactly.
There you have it. This is how they get a transformer to run down a busy high street and meteors to smash into entire cities.