PCL常见编程问题

【原文:http://www.zhangzscn.com/2015/11/27/pcl开源库常见编程问题/】

针对大家在利用PCL开源进行开发过程中的常见问题,进行解答。本文会长期更新。
1.如何获取pcd文件点云里点的格式,比如是pcl::PointXYZ还是pcl::PointXYZRGB等类型?

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#include
#include
#include
#include
 
pcl::PCLPointCloud2 cloud;
pcl::PCDReader reader;
reader.readHeader( "C:\fandisk.pcd" , cloud);
for ( int i = 0; i < cloud.fields.size(); i++)
{
     std::cout << cloud.fields[i].name;
}

2.如何实现类似pcl::PointCloud::Ptr和pcl::PointCloud的两个类相互转换?

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#include
#include
#include
 
pcl::PointCloud::Ptr cloudPointer( new pcl::PointCloud);
pcl::PointCloud cloud;
cloud = *cloudPointer;
cloudPointer = cloud.makeShared();

3.如何加快ASCII格式存储,也就是记事本打开可以看到坐标数据的pcd文件读取速度?
建议将pcd文件换成以Binary格式存储。

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#include
#include
#include
#include
 
pcl::PointCloud::Ptr cloud( new pcl::PointCloud);
pcl::io::loadPCDFile( "C:\office3-after1.pcd" , *cloud);
pcl::io::savePCDFileBinary( "C:\office3-after21111.pcd" , *cloud);

4.如何给pcl::PointXYZ类型的点云在显示时指定颜色?

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#include
#include
#include
#include
 
pcl::PointCloud::Ptr cloud( new pcl::PointCloud);
pcl::io::loadPCDFile( "C:\office3-after21111.pcd" , *cloud);
 
pcl::visualization::PCLVisualizer viewer( "pointcloud viewer" );
pcl::visualization::PointCloudColorHandlerCustom sig(cloud, 0, 234, 0);
viewer.addPointCloud(cloud, sig, "cloud" );
while (!viewer.wasStopped())
{
     viewer.spinOnce();
}

5.如何查找点云的x,y,z的极值?

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#include
#include
#include
pcl::PointCloud::Ptr cloud;
cloud = pcl::PointCloud::Ptr ( new pcl::PointCloud);
pcl::io::loadPCDFile ( "your_pcd_file.pcd" , *cloud);
pcl::PointXYZ minPt, maxPt;
pcl::getMinMax3D (*cloud, minPt, maxPt);

6.如何判断点云中的点为无效点,即坐标值为nan,以及如何将点设置为无效点?

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#include
 
pcl::PointXYZ p_valid;
p_valid.x = 0;
p_valid.y = 0;
p_valid.z = 0;
std::cout << "Is p_valid valid? " << pcl::isFinite(p_valid) << std::endl;
 
pcl::PointXYZ p_invalid;
p_invalid.x = std::numeric_limits< float >::quiet_NaN();
p_invalid.y = 0;
p_invalid.z = 0;
std::cout << "Is p_invalid valid? " << pcl::isFinite(p_invalid) << std::endl;

7.如何将无效点从点云中移除?

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#include
#include
#include
 
typedef pcl::PointCloud CloudType;
CloudType::Ptr cloud( new CloudType);
cloud->is_dense = false ;
CloudType::Ptr output_cloud( new CloudType);
 
CloudType::PointType p_nan;
p_nan.x = std::numeric_limits< float >::quiet_NaN();
p_nan.y = std::numeric_limits< float >::quiet_NaN();
p_nan.z = std::numeric_limits< float >::quiet_NaN();
cloud->push_back(p_nan);
 
CloudType::PointType p_valid;
p_valid.x = 1.0f;
cloud->push_back(p_valid);
 
std::cout << "size: " << cloud->points.size() << std::endl;
 
std::vector< int > indices;
pcl::removeNaNFromPointCloud(*cloud, *output_cloud, indices);
std::cout << "size: " << output_cloud->points.size() << std::endl;

8.如果知道需要保存点的序号,如何从原点云中拷贝点到新点云?

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#include
#include
#include
#include
 
pcl::PointCloud::Ptr cloud( new pcl::PointCloud);
pcl::io::loadPCDFile( "C:\office3-after21111.pcd" , *cloud);
pcl::PointCloud::Ptr cloudOut( new pcl::PointCloud);
std::vector< int > indexs = { 1, 2, 5 };
pcl::copyPointCloud(*cloud, indexs, *cloudOut);

9.如何从点云里删除和添加点?

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#include "stdafx.h"
#include
#include
#include
#include
 
pcl::PointCloud::Ptr cloud( new pcl::PointCloud);
pcl::io::loadPCDFile( "C:\office3-after21111.pcd" , *cloud);
pcl::PointCloud::iterator index = cloud->begin();
cloud->erase(index); //删除第一个
index = cloud->begin() + 5;
cloud->erase(cloud->begin()); //删除第5个
pcl::PointXYZ point = { 1, 1, 1 };
//在索引号为5的位置1上插入一点,原来的点后移一位
cloud->insert(cloud->begin() + 5, point);
cloud->push_back(point); //从点云最后面插入一点
std::cout << cloud->points[5].x; //输出1

如果删除的点太多建议用上面的方法拷贝到新点云,再赋值给原点云,如果要添加很多点,建议先resize,然后用循环向点云里的添加。
10.PointCloud和PCLPointCloud2类型如何相互转换?

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#include
#include
 
pcl::PointCloud::Ptr cloud( new pcl::PointCloud);
pcl::PCLPointCloud2 cloud2;
pcl::io::loadPCDFile( "C:\office3-after21111.pcd" , cloud2);
pcl::fromPCLPointCloud2(cloud2, *cloud);
pcl::toPCLPointCloud2(*cloud, cloud2);

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