Compositing Images Using SketchUp and Artlantis - Google SketchUp Workshop: Modeling, Visualizing, and Illustrating - page 198

At this point, the principal difficulty is the absence of a magic and totally
automatic tool that allows you to painlessly composite a 3D vector model
onto a 2D bitmapped photograph. There are, however, some tools that can
ease the task of matching the perspective of the virtual building to that of a
photograph (see Figure 11.8).
FiG 11.8 Site photos taken from various angles.
FiG 11.9 Photoshop's interface, with Alpha mask applied to the image.