Projective Mappings for Image Warping
Paul S. Heckbert · 1995
.56> 6=0form the equivalence class of homogeneous representations for the real point #x; y# T . To recover the actual coordinates from a homogeneous vector, we simply divide by the homogeneous component; e.g., the homogeneous vector p =#xw;yw;w# T =#x 0 ;y 0 ;w# T represents the actual point #x; y# T =#x 0 =w;y 0 =w# T . This division, a projection onto the w =1plane, cancels the effect of scalar multiplication by w. When representing real points with homogeneous notation we could use any nonzero w, but it is usually most convenient to choose w =1so that the real coordinates can be recovered without division. Projective space also includes the