（十七）从测距图像中提取边界

Object(Obstacle) border：属于物体和的最外面的可见点；

Shadow border：背景中与物体相邻的点；

Veil points：Object border和Shadow border之间的插值点。

以下代码实现将点云投影为距离图像，然后再从距离图像中提取点云的边界。

range_image_border_extraction.cpp

/* \author Bastian Steder */
#include <iostream>
#include <pcl/range_image/range_image.h>
#include <pcl/io/pcd_io.h>
#include <pcl/visualization/range_image_visualizer.h>
#include <pcl/visualization/pcl_visualizer.h>
#include <pcl/features/range_image_border_extractor.h>
#include <pcl/console/parse.h>
#include <pcl/common/file_io.h> // for getFilenameWithoutExtensiontypedef pcl::PointXYZ PointType;// --------------------
// -----Parameters-----
// --------------------
float angular_resolution = 0.5f;
pcl::RangeImage::CoordinateFrame coordinate_frame = pcl::RangeImage::CAMERA_FRAME;
bool setUnseenToMaxRange = false;// --------------
// -----Help-----
// --------------
void printUsage (const char* progName)
{std::cout << "\n\nUsage: "<<progName<<" [options] <scene.pcd>\n\n"<< "Options:\n"<< "-------------------------------------------\n"<< "-r <float>   angular resolution in degrees (default "<<angular_resolution<<")\n"<< "-c <int>     coordinate frame (default "<< (int)coordinate_frame<<")\n"<< "-m           Treat all unseen points to max range\n"<< "-h           this help\n"<< "\n\n";
}// --------------
// -----Main-----
// --------------
int main (int argc, char** argv)
{// --------------------------------------// -----Parse Command Line Arguments-----// --------------------------------------if (pcl::console::find_argument (argc, argv, "-h") >= 0){printUsage (argv[0]);return 0;}if (pcl::console::find_argument (argc, argv, "-m") >= 0){setUnseenToMaxRange = true;std::cout << "Setting unseen values in range image to maximum range readings.\n";}int tmp_coordinate_frame;if (pcl::console::parse (argc, argv, "-c", tmp_coordinate_frame) >= 0){coordinate_frame = pcl::RangeImage::CoordinateFrame (tmp_coordinate_frame);std::cout << "Using coordinate frame "<< (int)coordinate_frame<<".\n";}if (pcl::console::parse (argc, argv, "-r", angular_resolution) >= 0)std::cout << "Setting angular resolution to "<<angular_resolution<<"deg.\n";angular_resolution = pcl::deg2rad (angular_resolution);// ------------------------------------------------------------------// -----Read pcd file or create example point cloud if not given-----// ------------------------------------------------------------------pcl::PointCloud<PointType>::Ptr point_cloud_ptr (new pcl::PointCloud<PointType>);pcl::PointCloud<PointType>& point_cloud = *point_cloud_ptr;pcl::PointCloud<pcl::PointWithViewpoint> far_ranges;Eigen::Affine3f scene_sensor_pose (Eigen::Affine3f::Identity ());std::vector<int> pcd_filename_indices = pcl::console::parse_file_extension_argument (argc, argv, "pcd");if (!pcd_filename_indices.empty ()){std::string filename = argv[pcd_filename_indices[0]];if (pcl::io::loadPCDFile (filename, point_cloud) == -1){std::cout << "Was not able to open file \""<<filename<<"\".\n";printUsage (argv[0]);return 0;}scene_sensor_pose = Eigen::Affine3f (Eigen::Translation3f (point_cloud.sensor_origin_[0],point_cloud.sensor_origin_[1],point_cloud.sensor_origin_[2]))* Eigen::Affine3f (point_cloud.sensor_orientation_); //std::string far_ranges_filename = pcl::getFilenameWithoutExtension (filename)+"_far_ranges.pcd";   "_far_ranges.pcd";if (pcl::io::loadPCDFile(far_ranges_filename.c_str(), far_ranges) == -1)std::cout << "Far ranges file \""<<far_ranges_filename<<"\" does not exists.\n";}else{std::cout << "\nNo *.pcd file given => Generating example point cloud.\n\n";for (float x=-0.5f; x<=0.5f; x+=0.01f){for (float y=-0.5f; y<=0.5f; y+=0.01f){PointType point;  point.x = x;  point.y = y;  point.z = 2.0f - y;point_cloud.push_back (point);}}point_cloud.width = point_cloud.size ();  point_cloud.height = 1;}// -----------------------------------------------// -----Create RangeImage from the PointCloud-----// -----------------------------------------------float noise_level = 0.0;float min_range = 0.0f;int border_size = 1;pcl::RangeImage::Ptr range_image_ptr (new pcl::RangeImage);pcl::RangeImage& range_image = *range_image_ptr;   range_image.createFromPointCloud (point_cloud, angular_resolution, pcl::deg2rad (360.0f), pcl::deg2rad (180.0f),scene_sensor_pose, coordinate_frame, noise_level, min_range, border_size);range_image.integrateFarRanges (far_ranges);if (setUnseenToMaxRange)range_image.setUnseenToMaxRange ();// --------------------------------------------// -----Open 3D viewer and add point cloud-----// --------------------------------------------pcl::visualization::PCLVisualizer viewer ("3D Viewer");viewer.setBackgroundColor (1, 1, 1);viewer.addCoordinateSystem (0.5f,  scene_sensor_pose);pcl::visualization::PointCloudColorHandlerCustom<PointType> point_cloud_color_handler (point_cloud_ptr, 0, 0, 0);viewer.addPointCloud (point_cloud_ptr, point_cloud_color_handler, "original point cloud");//PointCloudColorHandlerCustom<pcl::PointWithRange> range_image_color_handler (range_image_ptr, 150, 150, 150);//viewer.addPointCloud (range_image_ptr, range_image_color_handler, "range image");//viewer.setPointCloudRenderingProperties (PCL_VISUALIZER_POINT_SIZE, 2, "range image");// -------------------------// -----提取边界-----// -------------------------pcl::RangeImageBorderExtractor border_extractor (&range_image);pcl::PointCloud<pcl::BorderDescription> border_descriptions;border_extractor.compute (border_descriptions);// ----------------------------------// -----Show points in 3D viewer-----// ----------------------------------// object border, veil points 和shadow pointspcl::PointCloud<pcl::PointWithRange>::Ptr border_points_ptr(new pcl::PointCloud<pcl::PointWithRange>),veil_points_ptr(new pcl::PointCloud<pcl::PointWithRange>),shadow_points_ptr(new pcl::PointCloud<pcl::PointWithRange>);pcl::PointCloud<pcl::PointWithRange>& border_points = *border_points_ptr,& veil_points = * veil_points_ptr,& shadow_points = *shadow_points_ptr;// 不同类型的点for (int y=0; y< (int)range_image.height; ++y){for (int x=0; x< (int)range_image.width; ++x){        if (border_descriptions[y*range_image.width + x].traits[pcl::BORDER_TRAIT__OBSTACLE_BORDER])border_points.push_back (range_image[y*range_image.width + x]);if (border_descriptions[y*range_image.width + x].traits[pcl::BORDER_TRAIT__VEIL_POINT])veil_points.push_back (range_image[y*range_image.width + x]);if (border_descriptions[y*range_image.width + x].traits[pcl::BORDER_TRAIT__SHADOW_BORDER])shadow_points.push_back (range_image[y*range_image.width + x]);}}// 对不同类型的点采用不同颜色可视化pcl::visualization::PointCloudColorHandlerCustom<pcl::PointWithRange> border_points_color_handler (border_points_ptr, 0, 255, 0);viewer.addPointCloud<pcl::PointWithRange> (border_points_ptr, border_points_color_handler, "border points");viewer.setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 5, "border points");pcl::visualization::PointCloudColorHandlerCustom<pcl::PointWithRange> veil_points_color_handler (veil_points_ptr, 255, 0, 0);viewer.addPointCloud<pcl::PointWithRange> (veil_points_ptr, veil_points_color_handler, "veil points");viewer.setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 5, "veil points");pcl::visualization::PointCloudColorHandlerCustom<pcl::PointWithRange> shadow_points_color_handler (shadow_points_ptr, 0, 255, 255);viewer.addPointCloud<pcl::PointWithRange> (shadow_points_ptr, shadow_points_color_handler, "shadow points");viewer.setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 5, "shadow points");//-------------------------------------// -----Show points on range image-----// ------------------------------------pcl::visualization::RangeImageVisualizer* range_image_borders_widget = NULL;range_image_borders_widget =pcl::visualization::RangeImageVisualizer::getRangeImageBordersWidget (range_image, -std::numeric_limits<float>::infinity (), std::numeric_limits<float>::infinity (), false,border_descriptions, "Range image with borders");// -------------------------------------//--------------------// -----Main loop-----//--------------------while (!viewer.wasStopped ()){range_image_borders_widget->spinOnce ();viewer.spinOnce ();pcl_sleep(0.01);}
}

CmakeLists.txt

cmake_minimum_required(VERSION 3.5 FATAL_ERROR)project(range_image_border_extraction)find_package(PCL 1.3 REQUIRED)include_directories(${PCL_INCLUDE_DIRS})
link_directories(${PCL_LIBRARY_DIRS})
add_definitions(${PCL_DEFINITIONS})add_executable (range_image_border_extraction range_image_border_extraction.cpp)
target_link_libraries (range_image_border_extraction ${PCL_LIBRARIES})

编译并运行:

./range_image_border_extraction -m

指定点云:

./range_image_border_extraction table_scene_lms400.pcd  -m -r 0.4 -c 1

绿点为object border; 红色为veil points; 蓝色为shadow border

数据样本

官方文档