工程代码：简单地测试了k-d树的最近邻搜索功能

#include<pcl/point_cloud.h>
#include<pcl/kdtree/kdtree_flann.h>#include<iostream>
#include<vector>
#include<ctime>using namespace std;int
main(int argc, char** argv)
{//使用系统时间做随机数种子srand(time(NULL));//创建一个PointXYZ类型点云指针pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);//初始化点云数据cloud->width = 1000;//宽为1000cloud->height = 1;//高为1，说明为无序点云cloud->points.resize(cloud->width * cloud->height);//使用随机数填充数据for (size_t i = 0; i < cloud->size(); ++i){//PointCloud类中对[]操作符进行了重载，返回的是对points的引用// (*cloud)[i].x 等同于 cloud->points[i].x(*cloud)[i].x = 1024.0f * rand() / (RAND_MAX + 1.0f);cloud->points[i].y = 1024.0f * rand() / (RAND_MAX + 1.0f);//推进写法cloud->points[i].z = 1024.0f * rand() / (RAND_MAX + 1.0f);//推进写法}//创建kd树对象pcl::KdTreeFLANN<pcl::PointXYZ> kdtree;//设置点云输入,将在cloud中搜索kdtree.setInputCloud(cloud);//设置被搜索点,用随机数填充pcl::PointXYZ searchPoint;searchPoint.x = 1024.0f * rand() / (RAND_MAX + 1.0f);searchPoint.y = 1024.0f * rand() / (RAND_MAX + 1.0f);searchPoint.z = 1024.0f * rand() / (RAND_MAX + 1.0f);//开始k最近邻搜索int K = 10;vector<int> pointIdxNKNSearch(K);vector<float> pointNKNSquaredDistance(K);cout << "K nearest neighbor search at (" << searchPoint.x<< " " << searchPoint.y<< " " << searchPoint.z<< ") with K = " << K << endl;if (kdtree.nearestKSearch(searchPoint, K, pointIdxNKNSearch, pointNKNSquaredDistance) > 0){for (size_t i = 0; i < pointIdxNKNSearch.size(); ++i){cout << "    " << cloud->points[pointIdxNKNSearch[i]].x<< " " << cloud->points[pointIdxNKNSearch[i]].x<< " " << cloud->points[pointIdxNKNSearch[i]].z<< "( squared distance: " << pointNKNSquaredDistance[i] << " )";}}//基于半径的邻域搜索//搜索结果保存在两个数组中，一个是下标，一个是距离vector<int> pointIdxRadiusSearch;vector<float> pointRadiusSquaredDistance;//设置搜索半径，随机值float radius = 256.0f* rand() / (RAND_MAX + 1.0f);cout << "Neighbors within radius search at (" << searchPoint.x<< " " << searchPoint.y<< " " << searchPoint.z<< ") with radius=" << radius << endl;if (kdtree.radiusSearch(searchPoint, radius, pointIdxRadiusSearch, pointRadiusSquaredDistance) > 0){for (size_t i = 0; i < pointIdxRadiusSearch.size(); ++i){cout << "    " << cloud->points[pointIdxRadiusSearch[i]].x<< " " << cloud->points[pointIdxRadiusSearch[i]].x<< " " << cloud->points[pointIdxRadiusSearch[i]].z<< "( squared distance: " << pointRadiusSquaredDistance[i] << " )";}}return 0;
}

但出现了如下错误：

error C3861: “pop_t”: 找不到标识符

 解决办法

打开pcl 1.8.1\3rdparty\flann\include\flann\algorithms\dist.h文件：

错误定位在了523行：

result = lut(reinterpret_cast<const unsigned char*> (a),reinterpret_cast<const unsigned char*> (b), size * sizeof(pop_t));

原来是在当前作用域中找不到pop_t数据类型的定义，从上文代码中，将相关的定义复制到当前作用域中即可：

typedef unsigned long long pop_t;

 

重新编译，问题解决。