System information (version)

• OpenCV => latest (4.5)
• Operating System / Platform =>Windows 64 Bit
• Compiler =>Visual Studio 2017

Detailed description

Current RotationWarper is missing functionality to reproject points from warped space back to rectilinear space, so for instance constructing homography with fisheye lens or for a panoramic video is not possible.

PR with proposed functionality: #18607

Steps to reproduce

Ptr<WarperCreator> creator = makePtr<PlaneWarper>();
Ptr<detail::RotationWarper> warper = creator->create(1);
Point2f pt(.5,1);
Mat I = Mat::eye(3, 3, CV_32FC1);
Point2f projected_pt = warper->warpPoint(pt, I, I);
Point2f reprojected_pt = warper->warpPointBackward(projected_pt, I, I);  
// reprojected_pt should be close to pt

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues,
  answers.opencv.org, Stack Overflow, etc and have not found solution
• I updated to latest OpenCV version and the issue is still there
• There is reproducer code and related data files: videos, images, onnx, etc