如何挑選從觀衆兩點PCL

Question

我想從點雲選取兩個點和返回兩個點的座標。爲了獲得下來的問題，我已經使用PCL的PointPickingEvent，並書面含點雲，可視化工具類，以及向量來存儲選定點。我的代碼：

#include <pcl/point_cloud.h> 
#include <pcl/PCLPointCloud2.h> 
#include <pcl/io/io.h> 
#include <pcl/io/pcd_io.h> 
#include <pcl/common/io.h> 
#include <pcl/io/ply_io.h> 
#include <pcl/io/vtk_lib_io.h> 
#include <pcl/visualization/pcl_visualizer.h> 

using namespace pcl; 
using namespace std; 

class pickPoints { 
public: 

    pickPoints::pickPoints() { 
     viewer.reset (new pcl::visualization::PCLVisualizer ("Viewer", true)); 
     viewer->registerPointPickingCallback (&pickPoints::pickCallback, *this); 
    } 

    ~pickPoints() {} 

    void setInputCloud (PointCloud<PointXYZ>::Ptr cloud) 
    { 
     cloudTemp = cloud; 
    } 

    vector<float> getpoints() { 
     return p; 
    } 

    void simpleViewer() 
    { 
     // Visualizer 
     viewer->addPointCloud<pcl::PointXYZ>(cloudTemp, "Cloud"); 
     viewer->resetCameraViewpoint ("Cloud"); 
     viewer->spin(); 
    } 

protected: 
    void pickCallback (const pcl::visualization::PointPickingEvent& event, void*) 
    { 
     if (event.getPointIndex() == -1) 
      return; 

     PointXYZ picked_point1,picked_point2; 
     event.getPoints(picked_point1.x,picked_point1.y,picked_point1.z, 
      picked_point2.x,picked_point2.y,picked_point2.z); 
     p.push_back(picked_point1.x); // store points 
     p.push_back(picked_point1.y); 
     p.push_back(picked_point1.z); 
     p.push_back(picked_point2.x); 
     p.push_back(picked_point2.y); 
     p.push_back(picked_point2.z); 

     //cout<<"first selected point: "<<p[0]<<" "<<p[1]<<" "<<p[2]<<endl; 
     //cout<<"second selected point: "<<p[3]<<" "<<p[4]<<" "<<p[5]<<endl; 
    } 

private: 
    // Point cloud data 
    PointCloud<pcl::PointXYZ>::Ptr cloudTemp; 

    // The visualizer 
    boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer; 

    // The picked point 
    vector<float> p; 
}; 

int main() 
{ 
    //LOAD; 
    PointCloud<PointXYZ>::Ptr cloud (new PointCloud<PointXYZ>()); 
    pcl::PolygonMesh mesh; 
    pcl::io::loadPolygonFilePLY("test.ply", mesh); 
    pcl::fromPCLPointCloud2(mesh.cloud, *cloud); 

    pickPoints pickViewer; 
    pickViewer.setInputCloud(cloud); // A pointer to a cloud 
    pickViewer.simpleViewer(); 
    vector<float> pointSelected; 
    pointSelected= pickViewer.getpoints(); 

    cout<<pointSelected[0]<<" "<<pointSelected[1]<<" "<<pointSelected[2]<<endl; 
    cout<<pointSelected[3]<<" "<<pointSelected[4]<<" "<<pointSelected[5]<<endl; 

    cin.get(); 
    return 0; 
} 

但是，當代碼被調試時，我什麼都沒有。我也知道，按左鍵拾取點時，SHIFT鍵應該按下。預先感謝您的任何幫助！

Answer 1

我發現，如我所料的getPoints（）方法不起作用。然而，用GetPoint（）運作良好。這裏是代碼打印出所選擇的點，並將它們存儲在一個向量：

std::vector<pcl::PointXYZ> selectedPoints; 

void pointPickingEventOccurred(const pcl::visualization::PointPickingEvent& event, void* viewer_void) 
{ 
    float x, y, z; 
    if (event.getPointIndex() == -1) 
    { 
     return; 
    } 
    event.getPoint(x, y, z); 
    std::cout << "Point coordinate (" << x << ", " << y << ", " << z << ")" << std::endl; 
    selectedPoints.push_back(pcl::PointXYZ(x, y, z)); 
} 

void displayCloud(pcl::PointCloud<pcl::PointXYZI>::Ptr cloud, const std::string& window_name) 
{ 
    if (cloud->size() < 1) 
    { 
     std::cout << window_name << " display failure. Cloud contains no points\n"; 
     return; 
    } 

    boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer(new pcl::visualization::PCLVisualizer(window_name)); 
    pcl::visualization::PointCloudColorHandlerGenericField<pcl::PointXYZI> point_cloud_color_handler(cloud, "intensity"); 

    viewer->addPointCloud<pcl::PointXYZI>(cloud, point_cloud_color_handler, "id"); 
    viewer->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 2, "id"); 

    viewer->registerKeyboardCallback(keyboardEventOccurred, (void*)viewer.get()); 
    viewer->registerPointPickingCallback(pointPickingEventOccurred, (void*)&viewer); 

    while (!viewer->wasStopped() && !close_window){ 
     viewer->spinOnce(50); 
    } 
    close_window = false; 
    viewer->close(); 
} 

您還可以找到點之間的距離很容易，一旦他們被選中。

if (selectedPoints.size() > 1) 
    { 
     float distance = pcl::euclideanDistance(selectedPoints[0], selectedPoints[1]); 
     std::cout << "Distance is " << distance << std::endl; 
    } 

如果您希望重新開始拾取點，則可以使用keyboardEvent清空selectedPoints向量。