使用库：PCL
环境：乌班图18.04
语言：c++
程序如下：

#include <iostream>
#include <pcl/visualization/pcl_visualizer.h>  
#include <pcl/visualization/cloud_viewer.h>
#include <pcl/point_types.h>
#include <pcl/common/common.h>
#include <stdio.h>
#include <fstream> 
#include <sstream>
#include <unistd.h> 
#include <vector>
#include <pcl/visualization/pcl_visualizer.h>
#include <dirent.h>
#include <string>
#include <math.h>
#include <pcl/filters/random_sample.h>
void CreateCloudFromTxt(const std::string& file_path,pcl::PointCloud<pcl::PointXYZ>::Ptr cloud)
{
    std::ifstream file(file_path.c_str());
    std::string line;
    std::string no_use;
    pcl::PointXYZ point;
    while (getline(file, line)) {
        string::iterator it;
        for (it = line.begin(); it < line.end(); it++)
        {
          if (*it == ',')
          {
            line.erase(it);
            line.insert(it, ' ');
            it--;
          }
        }
        std::stringstream ss(line);
        ss >> point.x;
        ss >> point.y;
        ss >> point.z;
        cloud->push_back(point);
    }
    file.close();
}


void visualization(pcl::PointCloud<pcl::PointXYZ>::Ptr cloud)
{
    boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer(new pcl::visualization::PCLVisualizer("viewer"));
   
    pcl::visualization::PointCloudColorHandlerCustom<pcl::PointXYZ> single_color(cloud, 255, 0, 0);
    viewer->addPointCloud<pcl::PointXYZ>(cloud, single_color, "example");
    viewer->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 2, "example");

    while (!viewer->wasStopped()) {
        viewer->spinOnce(100);
        boost::this_thread::sleep(boost::posix_time::microseconds(100000));
    }
}

int main(int argc, char *argv[]) {
		pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);
		pcl::PointCloud<pcl::PointXYZ>::Ptr cloud_sample(new pcl::PointCloud<pcl::PointXYZ>);
		CreateCloudFromTxt(argv[1],cloud_in);
		pcl::RandomSample<pcl::PointXYZ> rs;
		rs.setInputCloud(cloud);
   		 //设置输出点的数量   
		rs.setSample(points_num);
    	//下采样并输出到cloud_sample
		rs.filter(*cloud_sample);
		visualization(cloud_sample);
		}