14Calibration = * Relationship between Ellipse center to Scene Image HomographyPupil CenterScene Position
15Solving for homographies X’ = Hx8 degrees of freedom in 3 x 3 matrix H, so at least n = 8 pairs of points are sufficient to determine itSet up a system of linear equations:Ah = 0where vector of unknowns h = [a,b,c,d,e,f,g,h]TNeed at least 8 eqs, but the more the better…Solve for h. solve using least-squares
16calibration method1. Look at Scene Marker and Press corresponding number on keyboard,2. Each marker press 2 to 3 times.3. Randomly select 8 pairs of points to calculate Homography.(Repeatly)3. Choose the best Homography matrix.