3D projective geometry
These concepts generalize naturally to 3D
•Homogeneous coordinates
–Projective 3D points have four coords:  P = (X,Y,Z,W)
•Duality
–A plane N is also represented by a 4-vector
–Points and planes are dual in 3D: N P=0
•Projective transformations
–Represented by 4x4 matrices T:  P’ = TP,    N’ = N T-1