msac.hpp

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 * $Id: msac.hpp 6144 2012-07-04 22:06:28Z rusu $
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#ifndef PCL_SAMPLE_CONSENSUS_IMPL_MSAC_H_
#define PCL_SAMPLE_CONSENSUS_IMPL_MSAC_H_

#include <pcl/sample_consensus/msac.h>

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

  iterations_ = 0;
  double d_best_penalty = std::numeric_limits<double>::max();
  double k = 1.0;

  std::vector<int> best_model;
  std::vector<int> selection;
  Eigen::VectorXf model_coefficients;
  std::vector<double> distances;

  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 ()) 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;
     }

    double d_cur_penalty = 0;
    // Iterate through the 3d points and calculate the distances from them to the model
    sac_model_->getDistancesToModel (model_coefficients, distances);
    
    if (distances.empty () && k > 1.0)
      continue;

    for (size_t i = 0; i < distances.size (); ++i)
      d_cur_penalty += (std::min) (distances[i], threshold_);

    // Better match ?
    if (d_cur_penalty < d_best_penalty)
    {
      d_best_penalty = d_cur_penalty;

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

      n_inliers_count = 0;
      // Need to compute the number of inliers for this model to adapt k
      for (size_t i = 0; i < distances.size (); ++i)
        if (distances[i] <= threshold_)
          ++n_inliers_count;

      // Compute the k parameter (k=log(z)/log(1-w^n))
      double w = static_cast<double> (n_inliers_count) / static_cast<double> (sac_model_->getIndices ()->size ());
      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 (1.0 - probability_) / log (p_no_outliers);
    }

    ++iterations_;
    if (debug_verbosity_level > 1)
      PCL_DEBUG ("[pcl::MEstimatorSampleConsensus::computeModel] Trial %d out of %d. Best penalty is %f.\n", iterations_, static_cast<int> (ceil (k)), d_best_penalty);
    if (iterations_ > max_iterations_)
    {
      if (debug_verbosity_level > 0)
        PCL_DEBUG ("[pcl::MEstimatorSampleConsensus::computeModel] MSAC reached the maximum number of trials.\n");
      break;
    }
  }

  if (model_.empty ())
  {
    if (debug_verbosity_level > 0)
      PCL_DEBUG ("[pcl::MEstimatorSampleConsensus::computeModel] Unable to find a solution!\n");
    return (false);
  }

  // Iterate through the 3d points and calculate the distances from them to the model again
  sac_model_->getDistancesToModel (model_coefficients_, distances);
  std::vector<int> &indices = *sac_model_->getIndices ();

  if (distances.size () != indices.size ())
  {
    PCL_ERROR ("[pcl::MEstimatorSampleConsensus::computeModel] Estimated distances (%zu) differs than the normal of indices (%zu).\n", distances.size (), indices.size ());
    return (false);
  }

  inliers_.resize (distances.size ());
  // Get the inliers for the best model found
  n_inliers_count = 0;
  for (size_t i = 0; i < distances.size (); ++i)
    if (distances[i] <= threshold_)
      inliers_[n_inliers_count++] = indices[i];

  // Resize the inliers vector
  inliers_.resize (n_inliers_count);

  if (debug_verbosity_level > 0)
    PCL_DEBUG ("[pcl::MEstimatorSampleConsensus::computeModel] Model: %zu size, %d inliers.\n", model_.size (), n_inliers_count);

  return (true);
}

#define PCL_INSTANTIATE_MEstimatorSampleConsensus(T) template class PCL_EXPORTS pcl::MEstimatorSampleConsensus<T>;

#endif    // PCL_SAMPLE_CONSENSUS_IMPL_MSAC_H_