一、PCL點雲平滑和法線估計
題目:https://mp.weixin.qq.com/s?__biz=MzIxOTczOTM4NA==&mid=2247486705&idx=1&sn=ca333d7bb12b7c226270e98d0003a789&chksm=97d7e966a0a06070a8dba605966016d227d7a6cad786498070d9e1b8cea8747470a4840257fd&scene=21#wechat_redirect
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* 題目:給定一個融合後的點雲,已經對其進行下采樣和濾波(代碼已給)。
* 請對其進行平滑(輸出結果),然後計算法線,并講法線顯示在平滑後的點雲上(提供截圖)。
*
* 本程式學習目标:
* 熟悉PCL的平滑、法線計算、顯示,為網格化做鋪墊。
*
* 公衆号:計算機視覺life。釋出于公衆号旗下知識星球:從零開始學習SLAM
* 時間:2018.12
****************************/
#include <pcl/point_types.h>
#include <pcl/io/io.h>
#include <pcl/io/pcd_io.h>
#include <pcl/visualization/cloud_viewer.h>
#include <pcl/filters/radius_outlier_removal.h>
#include <pcl/filters/voxel_grid.h>
#include <pcl/filters/statistical_outlier_removal.h>
#include <pcl/surface/mls.h>
#include <pcl/features/normal_3d.h>
typedef pcl::PointXYZRGB PointT;
int main(int argc, char** argv)
{
// Load input file
pcl::PointCloud<PointT>::Ptr cloud(new pcl::PointCloud<PointT>);
pcl::PointCloud<PointT>::Ptr cloud_downSampled(new pcl::PointCloud<PointT>);
pcl::PointCloud<PointT>::Ptr cloud_filtered(new pcl::PointCloud<PointT>);
pcl::PointCloud<PointT>::Ptr cloud_smoothed(new pcl::PointCloud<PointT>);
if (pcl::io::loadPCDFile("./fusedCloud.pcd", *cloud) == -1)
{
cout << "點雲資料讀取失敗!" << endl;
}
std::cout << "Orginal points number: " << cloud->points.size() << std::endl;
// 下采樣,同時保持點雲形狀特征
pcl::VoxelGrid<PointT> downSampled; //建立濾波對象
downSampled.setInputCloud (cloud); //設定需要過濾的點雲給濾波對象
downSampled.setLeafSize (0.01f, 0.01f, 0.01f); //設定濾波時建立的體素體積為1cm的立方體
downSampled.filter (*cloud_downSampled); //執行濾波處理,存儲輸出
std::cout<<"cloud_downSampled: " << cloud_downSampled->size()<<std::endl;
pcl::io::savePCDFile ("./downsampledPC.pcd", *cloud_downSampled);
// 統計濾波
pcl::StatisticalOutlierRemoval<PointT> statisOutlierRemoval; //建立濾波器對象
statisOutlierRemoval.setInputCloud (cloud_downSampled); //設定待濾波的點雲
statisOutlierRemoval.setMeanK (50); //設定在進行統計時考慮查詢點臨近點數
statisOutlierRemoval.setStddevMulThresh (3.0); //設定判斷是否為離群點的閥值:均值+1.0*标準差
statisOutlierRemoval.filter (*cloud_filtered); //濾波結果存儲到cloud_filtered
std::cout << "cloud_filtered: " << cloud_filtered->size()<<std::endl;
pcl::io::savePCDFile ("./filteredPC.pcd", *cloud_filtered);
// ----------------------開始你的代碼--------------------------//
// 請參考PCL官網實作以下功能
// 對點雲重采樣
pcl::search::KdTree<PointT>::Ptr treeSampling (new pcl::search::KdTree<PointT>);
pcl::PointCloud<PointT> mls_point;
pcl::MovingLeastSquares<PointT,PointT> mls;
mls.setComputeNormals(false);
mls.setInputCloud(cloud_filtered);
mls.setPolynomialOrder(2);
mls.setPolynomialFit(false);
mls.setSearchMethod(treeSampling);
mls.setSearchRadius(0.05);
mls.process(mls_point);
// 輸出重采樣結果
cloud_smoothed = mls_point.makeShared();
std::cout<<"cloud_smoothed: "<<cloud_smoothed->size() <<std::endl;
//save cloud_smoothed
pcl::io::savePCDFileASCII("cloud_smoothed.pcd",*cloud_smoothed);
// 法線估計
pcl::NormalEstimation<PointT,pcl::Normal> normalEstimation;
normalEstimation.setInputCloud(cloud_smoothed);
pcl::search::KdTree<PointT>::Ptr tree(new pcl::search::KdTree<PointT>);
normalEstimation.setSearchMethod(tree);
pcl::PointCloud<pcl::Normal>::Ptr normals(new pcl::PointCloud<pcl::Normal>);
normalEstimation.setKSearch(10);
normalEstimation.compute(*normals);
std::cout<<"normals: "<<normals->size()<<", "<<"normals fields: "<<pcl::getFieldsList(*normals)<<std::endl;
pcl::io::savePCDFileASCII("normals.pcd",*normals);
// ----------------------結束你的代碼--------------------------//
// 顯示結果
boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer (new pcl::visualization::PCLVisualizer ("PCL Viewer"));
viewer->setBackgroundColor (0, 0, 0);
pcl::visualization::PointCloudColorHandlerRGBField<PointT> rgb(cloud_smoothed);//color
viewer->addPointCloud<PointT> (cloud_smoothed, rgb, "smooth cloud");
viewer->setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 3, "smooth cloud");
viewer->addPointCloudNormals<PointT, pcl::Normal> (cloud_smoothed, normals, 10, 0.1, "normals");
viewer->initCameraParameters ();
while (!viewer->wasStopped ())
{
viewer->spinOnce (100);
boost::this_thread::sleep (boost::posix_time::microseconds (100000));
}
return 0;
}
1、控制法線顯示的數目:
viewer->addPointCloudNormals<PointT, pcl::Normal> (cloud_smoothed, normals, 10, 0.1, "normals");
10,就是每10個法線顯示一個。
0.1,就是每個法線的長度。
2、擷取PointCloud的Fields
pcl::getFieldsList(*normals)
二、貪婪三角化投影曲面重建
計算流程:點雲輸入 --> 下采樣 --> 統計濾波去除離群點 --> mls移動最小二乘法進行平滑處理 --> 對平滑後的點雲進行法線估計(有向點雲) --> 将法線和平滑後的點雲的Fields拼接在一起 --> 貪婪三角化 -->顯示輸出
/****************************
* 題目:給定一個融合後的點雲,已經對其進行下采樣和濾波(代碼已給)。
* 請對其進行平滑(輸出結果),然後計算法線,并講法線顯示在平滑後的點雲上(提供截圖)。
*
* 本程式學習目标:
* 熟悉PCL的平滑、法線計算、顯示,為網格化做鋪墊。
*
* 公衆号:計算機視覺life。釋出于公衆号旗下知識星球:從零開始學習SLAM
* 時間:2018.12
****************************/
#include <pcl/point_types.h>
#include <pcl/io/io.h>
#include <pcl/io/pcd_io.h>
#include <pcl/visualization/cloud_viewer.h>
#include <pcl/filters/radius_outlier_removal.h>
#include <pcl/filters/voxel_grid.h>
#include <pcl/filters/statistical_outlier_removal.h>
#include <pcl/surface/mls.h>
#include <pcl/features/normal_3d.h>
#include <pcl/surface/gp3.h>
typedef pcl::PointXYZ PointT;
int main(int argc, char** argv)
{
// Load input file
pcl::PointCloud<PointT>::Ptr cloud(new pcl::PointCloud<PointT>);
pcl::PointCloud<PointT>::Ptr cloud_downSampled(new pcl::PointCloud<PointT>);
pcl::PointCloud<PointT>::Ptr cloud_filtered(new pcl::PointCloud<PointT>);
pcl::PointCloud<PointT>::Ptr cloud_smoothed(new pcl::PointCloud<PointT>);
if (pcl::io::loadPCDFile("./fusedCloud.pcd", *cloud) == -1)
{
cout << "點雲資料讀取失敗!" << endl;
}
std::cout << "Orginal points number: " << cloud->points.size() << std::endl;
// 下采樣,同時保持點雲形狀特征
pcl::VoxelGrid<PointT> downSampled; //建立濾波對象
downSampled.setInputCloud (cloud); //設定需要過濾的點雲給濾波對象
downSampled.setLeafSize (0.01f, 0.01f, 0.01f); //設定濾波時建立的體素體積為1cm的立方體
downSampled.filter (*cloud_downSampled); //執行濾波處理,存儲輸出
std::cout<<"cloud_downSampled: " << cloud_downSampled->size()<<std::endl;
pcl::io::savePCDFile ("./downsampledPC.pcd", *cloud_downSampled);
// 統計濾波
pcl::StatisticalOutlierRemoval<PointT> statisOutlierRemoval; //建立濾波器對象
statisOutlierRemoval.setInputCloud (cloud_downSampled); //設定待濾波的點雲
statisOutlierRemoval.setMeanK (50); //設定在進行統計時考慮查詢點臨近點數
statisOutlierRemoval.setStddevMulThresh (3.0); //設定判斷是否為離群點的閥值:均值+1.0*标準差
statisOutlierRemoval.filter (*cloud_filtered); //濾波結果存儲到cloud_filtered
std::cout << "cloud_statical_filtered: " << cloud_filtered->size()<<std::endl;
pcl::io::savePCDFile ("./filteredPC.pcd", *cloud_filtered);
// ----------------------開始你的代碼--------------------------//
// 請參考PCL官網實作以下功能
// 對點雲重采樣
pcl::search::KdTree<PointT>::Ptr treeSampling (new pcl::search::KdTree<PointT>);
pcl::PointCloud<PointT> mls_point;
pcl::MovingLeastSquares<PointT,PointT> mls;
mls.setComputeNormals(false);
mls.setInputCloud(cloud_filtered);
mls.setPolynomialOrder(2);
mls.setPolynomialFit(false);
mls.setSearchMethod(treeSampling);
mls.setSearchRadius(0.05);
mls.process(mls_point);
// 輸出重采樣結果
cloud_smoothed = mls_point.makeShared();
std::cout<<"cloud_smoothed: "<<cloud_smoothed->size() <<std::endl;
//save cloud_smoothed
pcl::io::savePCDFileASCII("cloud_smoothed.pcd",*cloud_smoothed);
// 法線估計
pcl::NormalEstimation<PointT,pcl::Normal> normalEstimation;
normalEstimation.setInputCloud(cloud_smoothed);
pcl::search::KdTree<PointT>::Ptr tree(new pcl::search::KdTree<PointT>);
normalEstimation.setSearchMethod(tree);
pcl::PointCloud<pcl::Normal>::Ptr normals(new pcl::PointCloud<pcl::Normal>);
normalEstimation.setKSearch(10);
normalEstimation.compute(*normals);
std::cout<<"normals: "<<normals->size()<<", "<<"normals fields: "<<pcl::getFieldsList(*normals)<<std::endl;
pcl::io::savePCDFileASCII("normals.pcd",*normals);
//Triangle Projection
pcl::PointCloud<pcl::PointNormal>::Ptr cloud_with_normals(new pcl::PointCloud<pcl::PointNormal>);
pcl::concatenateFields(*cloud_smoothed,*normals,*cloud_with_normals);
std::cout<<"cloud_with_normals fields: "<<pcl::getFieldsList(*cloud_with_normals)<<std::endl;
pcl::io::savePCDFileASCII("cloud_with_normals.pcd",*cloud_with_normals);
pcl::search::KdTree<pcl::PointNormal>::Ptr tree2(new pcl::search::KdTree<pcl::PointNormal>);
tree2->setInputCloud(cloud_with_normals);
pcl::GreedyProjectionTriangulation<pcl::PointNormal> gp3;
pcl::PolygonMesh triangles;
gp3.setSearchRadius(0.1);
gp3.setMu(2.5);
gp3.setMaximumNearestNeighbors(52);
gp3.setMaximumAngle(2*M_PI/3);
gp3.setMinimumAngle(M_PI/18);
gp3.setMaximumSurfaceAngle(M_PI/4);
gp3.setNormalConsistency(false);
gp3.setInputCloud(cloud_with_normals);
gp3.setSearchMethod(tree2);
gp3.reconstruct(triangles);
// ----------------------結束你的代碼--------------------------//
// 顯示結果
boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer (new pcl::visualization::PCLVisualizer ("PCL Viewer"));
viewer->setBackgroundColor (0, 0, 0);
/*
pcl::visualization::PointCloudColorHandlerRGBField<PointT> rgb(cloud_smoothed);//color
viewer->addPointCloud<PointT> (cloud_smoothed, rgb, "smooth cloud");
viewer->setPointCloudRenderingProperties (pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 3, "smooth cloud");
viewer->addPointCloudNormals<PointT, pcl::Normal> (cloud_smoothed, normals, 10, 0.1, "normals");
*/
viewer->addPolygonMesh(triangles,"GPTriangle");
viewer->addText("GPTriangle",0,0,"GPTriangle");
viewer->initCameraParameters ();
while (!viewer->wasStopped ())
{
viewer->spinOnce (100);
boost::this_thread::sleep (boost::posix_time::microseconds (100000));
}
return 0;
}
參考:https://cloud.tencent.com/developer/article/1436518
可視化:
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsICM38FdsYkRGZkRG9lcvx2bjxiNx8VZ6l2csYDcuVWdWhVZx40MMBjVtJWd0ckW65UbM5WOHJWa5kHT20ESjBjUIF2X0hXZ0xCMx81dvRWYoNHLrdEZwZ1Rh5WNXp1bwNjW1ZUba9VZwlHdssmch1mclRXY39CXldWYtlWPzNXZj9mcw1ycz9WL49zZuBnL5EjNwAzMyQTM3ATOwkTMwIzLc52YucWbp5GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.png)
重建效果圖2:
幾個需要注意的地方:
1、貪婪三角化算法必須要求點雲是平滑的,且密度變化均勻(這也是上一步為什麼要做一個平滑處理)。
2、 貪婪投影三角化要求輸入的點雲必須是有向點雲,是以對平滑後的點雲進行法向量估計,并且将其Fields拼接在一起
3、拼接Fields的時候函數
pcl::concatenateFields
隻能接受PointXYZ類型的點雲資料,對于平滑後的帶有RGB資訊的點雲要将其以PointXYZ的類型讀入。
4、重建結果顯示是函數
viewer->addPolygonMesh(triangles,"GPTriangle");