Shigang Li Saburo Tsuji Masakazu Imai Determining of camera rotation from vanishing points of lines on horizontal planes. 499-502 1990 ICCV http://dx.doi.org/10.1109/ICCV.1990.139581 conf/iccv/1990 db/conf/iccv/iccv1990.html#LiTI90