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ransacReprojThreshold?

asked 2012-10-01 06:58:15 -0500

yes123 gravatar image

Hello guys,

I am investigating further into RANSAC with Homography.

One thing i don't fully understand is this formula:

What HsrcPointsi rapresents here?

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answered 2012-10-02 04:04:32 -0500

Ben gravatar image

RANSAC gets as input a set of matches and randomly selects some of them to compute a homography H. It then tests, how many matches 'fit' to this homography. If a match is good enough, it counts as an inlier. This is repeated many times and hopefully, RANSAC will find a homography that has many inliers and thus a good score.

The above formula is the test that defines, whether a match is an inlier or not. Given a match m(srcPoint, dstPoint) and a homography H, m is an outlier, if the distance between dstPoint and H*srcPoint (homography applied to srcPoint) is greater than ransacReprojThreshold.

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initally i wasn't understanding it correctly because on willowgarage the documentation http://opencv.willowgarage.com/documentation/python/camera_calibration_and_3d_reconstruction.html#findhomography reports HsrcPoints (that has no mean) while on opencv.org H * srcPoints that is the correct documentation

yes123 gravatar imageyes123 ( 2012-10-02 10:33:51 -0500 )edit
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Asked: 2012-10-01 06:58:15 -0500

Seen: 1,766 times

Last updated: Oct 02 '12