ransac.hpp

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#ifndef PCL_SAMPLE_CONSENSUS_IMPL_RANSAC_H_
#define PCL_SAMPLE_CONSENSUS_IMPL_RANSAC_H_

#include <pcl/sample_consensus/ransac.h>

template <typename PointT> bool
pcl::RandomSampleConsensus<PointT>::computeModel (int)
{
  // Warn and exit if no threshold was set
  if (threshold_ == std::numeric_limits<double>::max())
  {
    PCL_ERROR ("[pcl::RandomSampleConsensus::computeModel] No threshold set!\n");
    return (false);
  }

  iterations_ = 0;
  int n_best_inliers_count = -INT_MAX;
  double k = 1.0;

  std::vector<int> selection;
  Eigen::VectorXf model_coefficients;

  double log_probability  = log (1.0 - probability_);
  double one_over_indices = 1.0 / static_cast<double> (sac_model_->getIndices ()->size ());

  int n_inliers_count = 0;
  unsigned skipped_count = 0;
  // supress infinite loops by just allowing 10 x maximum allowed iterations for invalid model parameters!
  const unsigned max_skip = max_iterations_ * 10;
  
  // Iterate
  while (iterations_ < k && skipped_count < max_skip)
  {
    // Get X samples which satisfy the model criteria
    sac_model_->getSamples (iterations_, selection);

    if (selection.empty ()) 
    {
      PCL_ERROR ("[pcl::RandomSampleConsensus::computeModel] No samples could be selected!\n");
      break;
    }

    // Search for inliers in the point cloud for the current plane model M
    if (!sac_model_->computeModelCoefficients (selection, model_coefficients))
    {
      //++iterations_;
      ++skipped_count;
      continue;
    }

    // Select the inliers that are within threshold_ from the model
    //sac_model_->selectWithinDistance (model_coefficients, threshold_, inliers);
    //if (inliers.empty () && k > 1.0)
    //  continue;

    n_inliers_count = sac_model_->countWithinDistance (model_coefficients, threshold_);

    // Better match ?
    if (n_inliers_count > n_best_inliers_count)
    {
      n_best_inliers_count = n_inliers_count;

      // Save the current model/inlier/coefficients selection as being the best so far
      model_              = selection;
      model_coefficients_ = model_coefficients;

      // Compute the k parameter (k=log(z)/log(1-w^n))
      double w = static_cast<double> (n_best_inliers_count) * one_over_indices;
      double p_no_outliers = 1.0 - pow (w, static_cast<double> (selection.size ()));
      p_no_outliers = (std::max) (std::numeric_limits<double>::epsilon (), p_no_outliers);       // Avoid division by -Inf
      p_no_outliers = (std::min) (1.0 - std::numeric_limits<double>::epsilon (), p_no_outliers);   // Avoid division by 0.
      k = log_probability / log (p_no_outliers);
    }

    ++iterations_;
    PCL_DEBUG ("[pcl::RandomSampleConsensus::computeModel] Trial %d out of %f: %d inliers (best is: %d so far).\n", iterations_, k, n_inliers_count, n_best_inliers_count);
    if (iterations_ > max_iterations_)
    {
      PCL_DEBUG ("[pcl::RandomSampleConsensus::computeModel] RANSAC reached the maximum number of trials.\n");
      break;
    }
  }

  PCL_DEBUG ("[pcl::RandomSampleConsensus::computeModel] Model: %zu size, %d inliers.\n", model_.size (), n_best_inliers_count);

  if (model_.empty ())
  {
    inliers_.clear ();
    return (false);
  }

  // Get the set of inliers that correspond to the best model found so far
  sac_model_->selectWithinDistance (model_coefficients_, threshold_, inliers_);
  return (true);
}

#define PCL_INSTANTIATE_RandomSampleConsensus(T) template class PCL_EXPORTS pcl::RandomSampleConsensus<T>;

#endif    // PCL_SAMPLE_CONSENSUS_IMPL_RANSAC_H_