matlab - Can't compute homography -

matlab - Can't compute homography -

i'm quite inexperienced matlab , image processing, , i've been struggling problem past few days.

i have 12 point correspondence between coplanar plane coordinates , image projections. know intrinsics of camera. understood, plenty compute homography. (my final goal obtain extrinsic parameters of camera, believe straightforward after computing homography h.)

i've tried different methods obtain h, different matrix each method/function try, when apparently have same input/output. example, using vgg_h_from_x_lin(x1,x2) found here http://www.robots.ox.ac.uk/~vgg/hzbook/code/ , homography_solve http://www.mathworks.com/matlabcentral/answers/26141-homography-matrix gives me 2 different matrices.

i've tried well, https://cseweb.ucsd.edu/classes/wi07/cse252a/homography_estimation/homography_estimation.pdf , led me different h.

what doing wrong here? should quite simple have point correspondence , photographic camera intrinsics, can't understand how compute h correctly.

thanks in advance.

matlab camera-calibration homography