Camera Mapping is a technique used for matte paintings by turning a flat 2D photograph into a 3D animation using 3D Application like Maya, this technique is also called “Camera Projection”.
Shaded Projection
How It Works
Grap the 2d image to a 3D Application then create simple 3d geometries as the objects in the 2D image and try to match the position and the scale of the objects then use the camera to project the material (the 2d image) to the greometries they enjoy playing with the camera 
Geometry Wires
Advantages and Disadvantages
The best advantage of this technique is to animate and walk through a 2d image but the woth disadvantage is that you don’t have much space to move the camera, for example if have an image of a building and the sky is behind it, if you moved alot in the sence a gap will appeare behind the building becouse there can’t be nothing behind the building in the 2d image, so you don’t have much of space to animate the camera to avoid the gaps.
Original 2D Image
Jon
You can really increase the range of motion available to the camera within the scene by extending out the individual layers of your matte painting/photograph in Photoshop. This will get rid of any of the gaps that start to appear with the camera parallax.