利用最小二乘法估计样点表面法向，并显示

#include <pcl/point_types.h>

#include <pcl/io/pcd_io.h>

#include <pcl/kdtree/kdtree_flann.h>

#include <pcl/features/normal_3d.h>

#include <pcl/surface/gp3.h>

#include <pcl/visualization/pcl_visualizer.h>

int

main (int argc, char** argv)

{

        //加载点云模型

        pcl::PointCloud<pcl::PointXYZ>::Ptr cloud (new pcl::PointCloud<pcl::PointXYZ>);

        // pcl::PCLPointCloud2 cloud_blob;

        if(pcl::io::loadPCDFile<pcl::PointXYZ> ("foot.pcd", *cloud) == -1){

                PCL_ERROR("Could not read file \n");

        }

        //* the data should be available in cloud

        // Normal estimation*

        //法向计算

        pcl::NormalEstimation<pcl::PointXYZ, pcl::Normal> n;

        pcl::PointCloud<pcl::Normal>::Ptr normals (new pcl::PointCloud<pcl::Normal>);

        //建立kdtree来进行近邻点集搜索

        pcl::search::KdTree<pcl::PointXYZ>::Ptr tree (new pcl::search::KdTree<pcl::PointXYZ>);

        //为kdtree添加点云数据

        tree->setInputCloud (cloud);

        n.setInputCloud (cloud);

        n.setSearchMethod (tree);

        //点云法向计算时，需要搜索的近邻点大小

        n.setKSearch (20);

        //开始进行法向计算

        n.compute (*normals);

        //* normals should not contain the point normals + surface curvatures

        // Concatenate the XYZ and normal fields*

        //将点云数据与法向信息拼接

        pcl::PointCloud<pcl::PointNormal>::Ptr cloud_with_normals (new pcl::PointCloud<pcl::PointNormal>);

        pcl::concatenateFields (*cloud, *normals, *cloud_with_normals);

        /*图形显示模块*/

        //显示设置

        boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer (new pcl::visualization::PCLVisualizer ("3D Viewer"));

        //设置背景色

        viewer->setBackgroundColor (0, 0, 0.7);

        //设置点云颜色，该处为单一颜色设置

        pcl::visualization::PointCloudColorHandlerCustom<pcl::PointXYZ> single_color(cloud, 0, 255, 0);

        //添加需要显示的点云数据

        viewer->addPointCloud<pcl::PointXYZ> (cloud, single_color, "sample cloud");

        //设置点显示大小

        viewer->setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 1, "sample cloud");

        //添加需要显示的点云法向。cloud为原始点云模型，normal为法向信息，10表示需要显示法向的点云间隔，即每10个点显示一次法向，５表示法向长度。

        viewer->addPointCloudNormals<pcl::PointXYZ, pcl::Normal> (cloud, normals, 10, 5, "normals");

        //--------------------

        while (!viewer->wasStopped ())

                {

                        viewer->spinOnce (100);

                        boost::this_thread::sleep (boost::posix_time::microseconds (100000));

                }

        // Finish

        return (0);

}