// Copyright (c) 2022, ETH Zurich and UNC Chapel Hill.
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// Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de)

#ifndef COLMAP_SRC_ESTIMATORS_AFFINE_TRANSFORM_H_
#define COLMAP_SRC_ESTIMATORS_AFFINE_TRANSFORM_H_

#include <vector>

#include <Eigen/Core>

#include "util/alignment.h"
#include "util/types.h"

namespace colmap {

class AffineTransformEstimator {
 public:
  typedef Eigen::Vector2d X_t;
  typedef Eigen::Vector2d Y_t;
  typedef Eigen::Matrix<double, 2, 3> M_t;

  // The minimum number of samples needed to estimate a model.
  static const int kMinNumSamples = 3;

  // Estimate the affine transformation from at least 3 correspondences.
  static std::vector<M_t> Estimate(const std::vector<X_t>& points1,
                                   const std::vector<Y_t>& points2);

  // Compute the squared transformation error.
  static void Residuals(const std::vector<X_t>& points1,
                        const std::vector<Y_t>& points2, const M_t& E,
                        std::vector<double>* residuals);
};

}  // namespace colmap

#endif  // COLMAP_SRC_ESTIMATORS_AFFINE_TRANSFORM_H_