Properly fix inf/inf issue in MCC

[vrabaud]

Properly fix #3316

Without this fix, we could end up with 4 corners, which might seem valid, while some of those are (0,0).

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[asmorkalov]

@gursimarsingh please test and review.

[abhishek-gola]

Hi @vrabaud,
The change looks good to me. Using return instead of continue seems preferable here. Although continue still produces the correct output—since the specific checker box is ultimately rejected during the CCM evaluation due to a high error:-

   if (!cccm.evaluate(scm, offset, iTheta, error))
            continue;

using return will help avoiding unnecessary computations by exiting early.

[vrabaud]

It actually crashes for me: having two points that are the same find a matrix in

opencv_contrib/modules/mcc/src/checker_detector.cpp

Line 802 in eebd897

Matx33f ccT = cv::getPerspectiveTransform(points, chartPhy);

that is not invertible, creating Inf values again in

opencv_contrib/modules/mcc/src/checker_detector.cpp

Line 868 in eebd897

xt = ccT.inv() * p;

[gursimarsingh]

return help avoid overhead computation for unnecessary boxes