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I'm trying to understand the code of findhomography function, while for the pose refine after ransac/prosac, ie. the 'createLMSolver(makePtr<homographyrefinecallback>(src, dst), 10)->run(H8);' line in findHomography() function, I'm confused about the computation of the jacobian (in the compute() function of HomographyRefineCallback when implementing the LM solver:

Jptr[0] = Mxww; Jptr[1] = Myww; Jptr[2] = ww; Jptr[3] = Jptr[4] = Jptr[5] = 0.; Jptr[6] = -Mxwwxi; Jptr[7] = -Mywwxi; Jptr[8] = Jptr[9] = Jptr[10] = 0.; Jptr[11] = Mxww; Jptr[12] = Myww; Jptr[13] = ww; Jptr[14] = -Mxwwyi; Jptr[15] = -Mywwyi;

The source and dest points are 2d points, and the homography matrix to refine is a 3*3 matrix (opencv sets the last element to 1, so h has 8 elements here), so why the jacobian here has 16 elements? Could anyone explain it, or provide the original paper on this solution here?

Thanks!

I'm trying to understand the code of findhomography function, while for the pose refine after ransac/prosac, ie. the 'createLMSolver(makePtr<homographyrefinecallback>(src, createLMSolver(makePtr<HomographyRefineCallback>(src, dst), 10)->run(H8);' 10)->run(H8); line in findHomography() findHomography() function, I'm confused about the computation of the jacobian (in the compute() function of HomographyRefineCallback HomographyRefineCallback when implementing the LM solver:

Jptr[0] = Mxww; Mx*ww; Jptr[1] = Myww; My*ww; Jptr[2] = ww;
Jptr[3] = Jptr[4] = Jptr[5] = 0.;
Jptr[6] = -Mxwwxi; -Mx*ww*xi; Jptr[7] = -Mywwxi;
-My*ww*xi;
Jptr[8] = Jptr[9] = Jptr[10] = 0.;
Jptr[11] = Mxww; Mx*ww; Jptr[12] = Myww; My*ww; Jptr[13] = ww;
Jptr[14] = -Mxwwyi; -Mx*ww*yi; Jptr[15] = -Mywwyi;
-My*ww*yi;