PCL RANSAC点云配准

一、概述

  PCL中RANSAC点云配准的简单使用案例。

二、代码

alignment_prerejective.cpp

#include 

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// Types
typedef pcl::PointNormal PointNT;
typedef pcl::PointCloud<PointNT> PointCloudT;
typedef pcl::FPFHSignature33 FeatureT;
typedef pcl::FPFHEstimationOMP<PointNT,PointNT,FeatureT> FeatureEstimationT;
typedef pcl::PointCloud<FeatureT> FeatureCloudT;
typedef pcl::visualization::PointCloudColorHandlerCustom<PointNT> ColorHandlerT;

// Align a rigid object to a scene with clutter and occlusions
int
main (int argc, char **argv)
{
  // Point clouds
  PointCloudT::Ptr object (new PointCloudT);
  PointCloudT::Ptr object_aligned (new PointCloudT);
  PointCloudT::Ptr scene (new PointCloudT);
  FeatureCloudT::Ptr object_features (new FeatureCloudT);
  FeatureCloudT::Ptr scene_features (new FeatureCloudT);
  
  // Load object and scene
  pcl::console::print_highlight ("Loading point clouds...\n");
  if (pcl::io::loadPCDFile<PointNT>("chef.pcd", *object) < 0 ||
      pcl::io::loadPCDFile<PointNT>("rs1.pcd", *scene) < 0)
  {
    pcl::console::print_error ("Error loading object/scene file!\n");
    return (1);
  }
  
  // Downsample
  pcl::console::print_highlight ("Downsampling...\n");
  pcl::VoxelGrid<PointNT> grid;
  const float leaf = 0.005f;
  grid.setLeafSize (leaf, leaf, leaf);
  grid.setInputCloud (object);
  grid.filter (*object);
  grid.setInputCloud (scene);
  grid.filter (*scene);
  
  // Estimate normals for scene
  pcl::console::print_highlight ("Estimating scene normals...\n");
  pcl::NormalEstimationOMP<PointNT,PointNT> nest;
  nest.setRadiusSearch (0.01);
  nest.setInputCloud (scene);
  nest.compute (*scene);
  
  // Estimate features
  pcl::console::print_highlight ("Estimating features...\n");
  FeatureEstimationT fest;
  fest.setRadiusSearch (0.025);
  fest.setInputCloud (object);
  fest.setInputNormals (object);
  fest.compute (*object_features);
  fest.setInputCloud (scene);
  fest.setInputNormals (scene);
  fest.compute (*scene_features);
  
  // Perform alignment
  pcl::console::print_highlight ("Starting alignment...\n");
  pcl::SampleConsensusPrerejective<PointNT,PointNT,FeatureT> align;
  align.setInputSource (object);
  align.setSourceFeatures (object_features);
  align.setInputTarget (scene);
  align.setTargetFeatures (scene_features);
  align.setMaximumIterations (50000); // Number of RANSAC iterations
  align.setNumberOfSamples (3); // Number of points to sample for generating/prerejecting a pose
  align.setCorrespondenceRandomness (5); // Number of nearest features to use
  align.setSimilarityThreshold (0.9f); // Polygonal edge length similarity threshold
  align.setMaxCorrespondenceDistance (2.5f * leaf); // Inlier threshold
  align.setInlierFraction (0.25f); // Required inlier fraction for accepting a pose hypothesis
  {
    pcl::ScopeTime t("Alignment");
    align.align (*object_aligned);
  }
  
  if (align.hasConverged ())
  {
    // Print results
    printf ("\n");
    Eigen::Matrix4f transformation = align.getFinalTransformation ();
    pcl::console::print_info ("    | %6.3f %6.3f %6.3f | \n", transformation (0,0), transformation (0,1), transformation (0,2));
    pcl::console::print_info ("R = | %6.3f %6.3f %6.3f | \n", transformation (1,0), transformation (1,1), transformation (1,2));
    pcl::console::print_info ("    | %6.3f %6.3f %6.3f | \n", transformation (2,0), transformation (2,1), transformation (2,2));
    pcl::console::print_info ("\n");
    pcl::console::print_info ("t = < %0.3f, %0.3f, %0.3f >\n", transformation (0,3), transformation (1,3), transformation (2,3));
    pcl::console::print_info ("\n");
    pcl::console::print_info ("Inliers: %i/%i\n", align.getInliers ().size (), object->size ());
    
    // Show alignment
    pcl::visualization::PCLVisualizer visu("Alignment");
    visu.addPointCloud (scene, ColorHandlerT (scene, 0.0, 255.0, 0.0), "scene");
    visu.addPointCloud (object_aligned, ColorHandlerT (object_aligned, 0.0, 0.0, 255.0), "object_aligned");
    visu.spin ();
  }
  else
  {
    pcl::console::print_error ("Alignment failed!\n");
    return (1);
  }
  
  return (0);
}

三、结果

> Loading point clouds...
Failed to find match for field 'curvature'.
Failed to find match for field 'normal_x'.
Failed to find match for field 'normal_y'.
Failed to find match for field 'normal_z'.
Failed to find match for field 'curvature'.
> Downsampling...
> Estimating scene normals...
> Estimating features...
> Starting alignment...
Alignment took 986.837ms.

    |  0.871  0.194  0.451 |
R = | -0.479  0.135  0.867 |
    |  0.107 -0.972  0.210 |

t = < 0.238, 0.657, 0.730 >

Inliers: 1195/3432