"The American Video Graphics suit was originally filed against game software publishers Electronic Arts, Take-Two, Ubisoft, Activision, THQ, Vivendi Universal Games, Sega, Square Enix, Tecmo, Lucasarts, and Namco in August 2004, and alleged infringement of US Patent No. 4,734,690: method and apparatus for spherical panning.
"The patent in question was originally filed in 1987 by William G. Waller of company Tektronix, Inc., and covers the situation when "a graphics display terminal performs a pan operation with respect to a view motion center to effectuate spherical panning, thereby providing perspective and non-perspective views", in addition to a zoom feature. Taken in the context of video games, this would seem to mean that any 3D game engine that uses camera movement or zooming of any kind relative to a specific object would be liable, a description that encompasses the vast majority of current video games. ..."
Read article: Gamasutra - Atari, Other Parties Settle Major Game Patent Suit