Back 
Next
Geometric Transformations
Homogenous Coordinates
Translation, scaling and rotation are expressed (non-homogeneously) as:
Composition is difficult to express
Homogeneous coordinates allow all three to be expressed homogeneously, using multiplication by 
matrices
P2d (x, y) -> Ph (wx, wy, w), w xb9 0
Given Ph (x, y, w), w xb9 0
Then P2d (x, y) = P2d (x/w, y/w)
-
W is 1 for affine transformations in graphics
Back Next
Geometric Transformations - 09 MAY 95
Page 35 of 51
sl@cs.brown.edu
Generated with CERN WebMaker