Add 3d buildings to Live action Footage

In this video LightArchitect shows how to 3d track your live action footage in Blender and then recreate the lighting in Blender so that you can add cgi to over your footage in compositing. 

Motion Tracking is used to track the motion of objects and/or a camera and, through the constraints, to apply this tracking data to 3D objects (or just one), which have either been created in Blender or imported into the application. Blender’s motion tracker supports a couple of very powerful tools for 2D tracking and 3D motion reconstruction, including camera tracking and object tracking, as well as some special features like the plane track for compositing. Tracks can also be used to move and deform masks for rotoscoping in the Mask Editor, which is available as a special mode in the Movie Clip Editor.