Load and/or create a calibration file - v1

Instead of scaling with the height of the chosen person, you can now use a calibration file, which give more accurate results, more easily if the participants are not measured. The floor angle and the XY origin are recomputed.

Regardless of the chosen method, a calibration file is saved.

• The rotation and translation matrices are calculated from the estimated floor angle, estimated XY origin, and an arbitrary camera-to-subject distance (10 m by default)
• The intrinsic matrix is computed from the resolution of the video, the estimated floor angle, the height of the person in meters and in pixels, as well as the arbitrary camera-to-subject distance
• The distortion is assumed to be inexistent

This also allows for a better visualization with overlay of the OpenSim skeleton to the video.

Sports2D_demo_ft.mp4

Next goals:

• fix perspective effects
• let the user optionally specify
  • camera-to-subject distance
  • focal_distance
  • field of view
  • recalculate_extrinsics
• potentially also compensate for distorsion and for camera not parallel to the plane of motion

Full Changelog: v0.8.22...v0.8.23