TagDetection.h

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#ifndef TAGDETECTION_H
#define TAGDETECTION_H

#include "Shared/fmat.h"
#include "Shared/Measures.h"
#include <utility>
#include <vector>

namespace AprilTags {

struct TagDetection {

  //! Constructor
  TagDetection();

  //! Constructor for manually creating tags in a world map
  TagDetection(int id);

  //! Is the detection good enough?
  bool good;

  //! Observed code
  long long obsCode;

  //! Matched code
  long long code;

  //! What was the ID of the detected tag?
  int id;

  //! The hamming distance between the detected code and the true code
  int hammingDistance;
  
  //! How many 90 degree rotations were required to align the code (internal use only)
  int rotation;

  /////////////// Fields below are filled in by TagDetector ///////////////
  //! Position (in fractional pixel coordinates) of the detection.
  /*  The points travel counter-clockwise around the target, always
   *  starting from the same corner of the tag.
   */
  std::pair<float,float> p[4];

  //! Center of tag in pixel coordinates.
  std::pair<float,float> cxy;

  //! Measured in pixels, how long was the observed perimeter.
  /*! Observed perimeter excludes the inferred perimeter which is used to connect incomplete quads. */
  float observedPerimeter;

  //! A 3x3 homography that computes pixel coordinates from tag-relative coordinates.
  /*  Both the input and output coordinates are 2D homogeneous vectors, with y = Hx.
   *  'y' are pixel coordinates, 'x' are tag-relative coordinates. Tag coordinates span
   *  from (-1,-1) to (1,1). The orientation of the homography reflects the orientation
   *  of the target.
   */
  fmat::Matrix<3,3> homography;

  //! Orientation in the xy plane
  AngSignPi getXYOrientation() const;

  //! The homography is relative to image center, whose coordinates are below.
  std::pair<float,float> hxy;

  //! Interpolate point given (x,y) is in tag coordinate space from (-1,-1) to (1,1).
  std::pair<float,float> interpolate(float x, float y) const;

  //! Used to eliminate redundant tags
  bool overlapsTooMuch(const TagDetection &other) const;
};

} // namespace

#endif