点云数据x-y平面网格化（电力线巡检点云分类step1）

 机载激光雷达电力线巡检点云分类第一步，将点云数据投影到x-y平面网格划分，以下代码利用libLAS库读取las点云数据，利用pcl库对点云数据进行处理。
参考https://blog.csdn.net/ethan_guo/article/details/80621998
  1#include <vtkAutoInit.h>
  2 #include <QCoreApplication>
  3 #include <QDebug>
  4 #include <iostream>
  5 #include <QVector>
  6 #include <liblas/liblas.hpp>
  7 #include <pcl/io/pcd_io.h>
  8 #include <pcl/point_cloud.h>
  9 #include <pcl/point_types.h>
 10 #include <pcl/console/print.h>
 11 #include <pcl/filters/extract_indices.h>
 12 #include <pcl/visualization/cloud_viewer.h>
 13 #include <pcl/visualization/pcl_visualizer.h>
 14 using namespace std;
 15 VTK_MODULE_INIT(vtkRenderingOpenGL)
 16 //定义一个网格类型
 17 class Grid
 18 {
 19     public:
 20     bool  powerLine; //是否为电力线网格
 21     float h_mean;    //平均高程  
 22     float h_max;     //最大高程
 23     float h_min;     //最小高程
 24     int   num;       //点个数
 25     pcl::PointCloud<pcl::PointXYZRGB>::Ptr grid_cloud {new pcl::PointCloud<pcl::PointXYZRGB>};  //网格内点云
 26     pcl::PointIndices::Ptr grid_inliers {new pcl::PointIndices};                                //网格内点云索引
 27 };
 28 int main(int argc, char *argv[])
 29 {
 30     QCoreApplication a(argc, argv);
 31     pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud_in (new pcl::PointCloud<pcl::PointXYZRGB>); //输入点云
 32     pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud_out(new pcl::PointCloud<pcl::PointXYZRGB>); //输出点云
 33     ifstream ifs("F:/lidar/powerLine/pointCloud/pt000001.las", std::ios::in | std::ios::binary);
 34     liblas::ReaderFactory f;
 35     liblas::Reader reader = f.CreateWithStream(ifs);
 36     unsigned long intnPoints = reader.GetHeader().GetPointRecordsCount();
 37     double maxX = reader.GetHeader().GetMaxX();
 38     double maxY = reader.GetHeader().GetMaxY();
 39     double maxZ = reader.GetHeader().GetMaxZ();
 40     double minX = reader.GetHeader().GetMinX();
 41     double minY = reader.GetHeader().GetMinY();
 42     double minZ = reader.GetHeader().GetMinZ();
 43     printf("intnPoints is %ld\n", intnPoints);
 44     printf("maxX is %lf\nmaxY is %lf\nmaxZ is %lf\nminX is %lf\nminY is %lf\nminZ is %lf\n", maxX, maxY, maxZ, minX, minY, minZ);
 45     cloud_in->width    = intnPoints;
 46     cloud_in->height   = 1;
 47     cloud_in->is_dense = false;
 48     cloud_in->resize(intnPoints);
 49     int k = 0;
 50     while(reader.ReadNextPoint())
 51     {
 52         cloud_in->points[k].x = reader.GetPoint().GetX();
 53         cloud_in->points[k].y = reader.GetPoint().GetY();
 54         cloud_in->points[k].z = reader.GetPoint().GetZ();
 55         k++;
 56     }
 57     //定义一个抽取器
 58     pcl::ExtractIndices<pcl::PointXYZRGB> extract;
 59     float grid_size = 30.0;
 60     QVector<QVector<Grid>> grid;
 61     grid.resize(20);
 62     for(int h = 0; h < 20; ++h)
 63     {
 64         grid[h].resize(20);
 65     }
 66     int j;
 67     int i;
 68     int l = 0;
 69     for(size_t m = 0; m < cloud_in->size(); m++)
 70     {
 71         i = floor(fabs(cloud_in->points[m].x / grid_size));
 72         j = floor(fabs(cloud_in->points[m].y / grid_size));
 73         grid[i][j].grid_cloud->push_back(cloud_in->points[m]);
 74         grid[i][j].grid_inliers->indices.push_back(m);
 75         grid[i][j].grid_inliers->header = cloud_in->header;
 76     }
 77     std::cout << "grid.size() is "<<grid.size()<<std::endl;
 78     std::cout << grid[4][5].grid_inliers->indices.size()<<std::endl;
 79     pcl::PointIndices::Ptr Indices (new pcl::PointIndices);
 80     for(int i = 0; i < grid.size(); ++i)
 81     {
 82         for(int j = 0; j < grid[i].size(); ++j)
 83         {
 84             if(grid[i][j].grid_inliers->indices.size() < 100)
 85             {
 86                 std::cout<< "grid["<<i<<"]["<<j<<"]" << "is  empty"<<std::endl;
 87             }else {
 88                 std::cout<< "grid["<<i<<"]["<<j<<"]" << " has "<< grid[i][j].grid_inliers->indices.size() << " points!"<<std::endl;
 89                 Indices->indices.insert(Indices->indices.end(), grid[i][j].grid_inliers->indices.begin(), grid[i][j].grid_inliers->indices.end());
 90                 if((i+j)%2 == 0)
 91                 {
 92                     for(int k = 0; k < grid[i][j].grid_cloud->width; ++k)
 93                     {
 94                         grid[i][j].grid_cloud->points[k].r = 127;
 95                         grid[i][j].grid_cloud->points[k].g = 255;
 96                         grid[i][j].grid_cloud->points[k].b = 0;
 97                         int indice = grid[i][j].grid_inliers->indices[k];
 98                         cloud_in->points[indice].r = 127;
 99                         cloud_in->points[indice].g = 255;
100                         cloud_in->points[indice].b = 0;
101                     }
102                 }else {
103                     for(int k = 0; k < grid[i][j].grid_cloud->width; ++k)
104                     {
105                         grid[i][j].grid_cloud->points[k].r = 255;
106                         grid[i][j].grid_cloud->points[k].g = 20;
107                         grid[i][j].grid_cloud->points[k].b = 147;
108                         int indice = grid[i][j].grid_inliers->indices[k];
109                         cloud_in->points[indice].r = 255;
110                         cloud_in->points[indice].g = 20;
111                         cloud_in->points[indice].b = 147;
112                     }
113                 }
114             }
115         }
116     }
117     extract.setInputCloud(cloud_in);
118     extract.setIndices(Indices);
119     extract.setNegative(false);
120     extract.filter(*cloud_out);
121 
122     pcl::visualization::PCLVisualizer::Ptr viewer(new pcl::visualization::PCLVisualizer("powerLine"));
123     viewer->setBackgroundColor(0, 0, 0);
124     viewer->addCoordinateSystem(1.0);
125     pcl::visualization::PointCloudColorHandlerRGBField<pcl::PointXYZRGB> rgb(cloud_out);
126     viewer->addPointCloud(cloud_out, rgb, "cloud grid");
127     viewer->initCameraParameters();
128     while(!viewer->wasStopped())
129     {
130         viewer->spinOnce(100);
131         boost::this_thread::sleep(boost::posix_time::microseconds(100000));
132     }
133 
134     return a.exec();
135 }