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#include 
   
    #include 
    
     #include 
     
      #include 
      
       #include 
       
         typedef pcl::PointXYZRGBA PointT;typedef pcl::PointCloud
        
          PointCloudT; // Mutex: //进程锁boost::mutex cloud_mutex; //用于给回调函数的结构体定义// structure used to pass arguments to the callback functionstruct callback_args { PointCloudT::Ptr clicked_points_3d; pcl::visualization::PCLVisualizer::Ptr viewerPtr;}; //回调函数void pp_callback(const pcl::visualization::PointPickingEvent& event, void* args){ struct callback_args* data = (struct callback_args *)args; if (event.getPointIndex() == -1) return; PointT current_point; event.getPoint(current_point.x, current_point.y, current_point.z); //TODO data->clicked_points_3d->clear();//将上次选的点清空 data->clicked_points_3d->points.push_back(current_point);//添加新选择的点 // Draw clicked points in red:将选中点用红色标记 pcl::visualization::PointCloudColorHandlerCustom
         
           red(data->clicked_points_3d, 255, 0, 0); data->viewerPtr->removePointCloud("clicked_points"); data->viewerPtr->addPointCloud(data->clicked_points_3d, red, "clicked_points"); data->viewerPtr->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 10, "clicked_points"); std::cout << current_point.x << " " << current_point.y << " " << current_point.z << std::endl; } void main(){ std::string filename("rabbit.pcd"); //visualizer,定义可视化窗口 pcl::PointCloud
          
           ::Ptr cloud(new pcl::PointCloud
           
            ()); boost::shared_ptr
            
              viewer(new pcl::visualization::PCLVisualizer("viewer")); //读取点云数据 if (pcl::io::loadPCDFile(filename, *cloud)) { std::cerr << "ERROR: Cannot open file " << filename << "! Aborting..." << std::endl; return; } std::cout << cloud->points.size() << std::endl; // for not overwriting the point cloud //获得互斥体，期间不能修改点云 cloud_mutex.lock(); // Display pointcloud: //显示点云 viewer->addPointCloud(cloud, "rabbit"); //viewer->setCameraPosition(0, 0, -2, 0, -1, 0, 0); //设置相机位置 // Add point picking callback to viewer: //可视化窗口执行回调函数 struct callback_args cb_args; PointCloudT::Ptr clicked_points_3d(new PointCloudT); cb_args.clicked_points_3d = clicked_points_3d; cb_args.viewerPtr = pcl::visualization::PCLVisualizer::Ptr(viewer); //注册屏幕选点事件 viewer->registerPointPickingCallback(pp_callback, (void*)&cb_args); //Shfit+鼠标左键选择点 std::cout << "Shift+click on three floor points, then press 'Q'..." << std::endl; // Spin until 'Q' is pressed: //摁“Q”键结束 viewer->spin(); std::cout << "done." << std::endl; //释放互斥体 cloud_mutex.unlock(); while (!viewer->wasStopped()) { viewer->spinOnce(100); //100?? boost::this_thread::sleep(boost::posix_time::microseconds(100000)); }}
            
           
          
         
        
       
      
     
    
   

最终实现效果如下图：

代码中设计的类的理解/解释：

boost::mutex cloud_mutex：这是boost库中提供的的mutex类，可以和lock类通过组合轻易构建读写锁和互斥锁。其中mutex是对象类，lock类是模板类。mutex类主要有两种：boost::mutex，boost::shared_mutex，其中mutex有lock和unlock方法，shared_mutex除了提供lock和unlock方法外，还有shared_lock和shared_unlock方法。因此，boost::mutex为独占互斥类，boost::shared_mutex为共享互斥类。

参考链接：

pcl::visualization::PCLVisualizer：PCL中进行点云可视化的类。同样进行可视化的类还有CloudViewer类。后者不能用于多线程应用程序。

官方教程：

参考链接：

参考链接：

（1）

（2）

（3）PCL官方实例：