What's the unit of homography found by FindHomography() function in mainSift.cpp

[narutojxl]

Hello author,
Thanks for your sharing.
I notice in mainSift.cpp, we can find the two images transform by FindHomography() and ImproveHomography() functions. I have 2 trival questions to seek your confirmation.

• 1. Does variable homography represents SE(2), namely, [R, t; 0, 1]= [H[0], H[1], H[2]; H[3], H[4], H[5]; H[6], H[7], H[8]]?
• 2. If it is correct, the translation part t = [H[2], H[5] ] unit is pixel, or m? The rotaion part unit is rad.

CudaSift/mainSift.cpp

Lines 72 to 78 in 5bc874a

	// Match Sift features and find a homography
	for (int i=0;i<1;i++)
	MatchSiftData(siftData1, siftData2);
	float homography[9];
	int numMatches;
	FindHomography(siftData1, homography, &numMatches, 10000, 0.00f, 0.80f, 5.0);
	int numFit = ImproveHomography(siftData1, homography, 5, 0.00f, 0.80f, 3.0);

Best regards
narutojxl