Patents
SketchUp holds a U.S. Patent 6,628,279 on its "Push/Pull" technology:
"System and method for three-dimensional modeling: A three-dimensional design and modeling environment allows users to draw the outlines, or perimeters, of objects in a two-dimensional manner, similar to pencil and paper, already familiar to them. The two-dimensional, planar faces created by a user can then be pushed and pulled by editing tools within the environment to easily and intuitively model three-dimensional volumes and geometries."
The patent was applied for in November 2000, and awarded in September 2003.
Read more about this topic: Sketch Up