1.pcd檔案格式

pcl點雲庫官網pcd格式詳解

2.C++原始碼 

讀取思路：連續讀取前11行，獲得pcd檔案資訊頭，取得點雲端儲存方式(ascii或者binary)和點雲數量、點雲格式(XYZ,XYZI....)等關鍵資訊，然後按行依次讀取座標資料即可。

#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
#include <vector>

struct PointXYZ
{
	double x, y, z;
};

/*
  Author:chd_ayj
  Date:2018-6-8
  Description: read .PCD file
*/

//讀取pcd點雲檔案
void readPCDfile(const std::string finname, std::vector<PointXYZ>& points, const std::string foutname)
{
	std::ifstream fin(finname);
	if (fin.bad()){
		std::cout << "開啟檔案失敗！" << std::endl;
		return;
	}

	char s[11][1024]; //儲存Header
	int Points_Num; //點數量
	std::string data_columns_type; //列數: X Y Z
	std::string data_type; //點座標儲存方式(ascii或者binary)

	std::vector<PointXYZ> cloud;
	//連續讀取Header行數   
	std::cout << "start to read file header....." << std::endl;
	std::cout << "file header: " << std::endl;
	for (int i = 0; i < 11; ++i){
		fin.getline(s[i], 1024);
		//std::cout << "第" << i + 1 << "行：" << s[i] << std::endl;
		std::cout << s[i] << std::endl;

		//FIELDS x y z rgb
		if (i == 2){
			std::string s2 = s[2];
			size_t pos = s2.find("FIELDS");
			size_t size = s2.size();
			data_columns_type = s2.substr(pos + 7, size);
			//std::cout << "data_columns_type:" << data_columns_type << std::endl;
		}

		//POINTS xxx
		if (i == 9){
			std::string s9 = s[9], Points_Str;
			size_t pos = s9.find("POINTS");
			size_t size = s9.size();
			Points_Str = s9.substr(pos + 7, size);
			Points_Num = atoi(Points_Str.c_str());
			//std::cout << "Points:" << std::Points_Num << endl;
		}

		//DATA ascii或者binary
		if (i == 10){
			std::string s10 = s[10], DATA_SIZE;
			size_t pos = s10.find("DATA");
			size_t size = s10.size();
			data_type = s10.substr(pos + 5, size);
			//std::cout << "data_type:" << data_type << std::endl;
		}
	}
	std::cout << std::endl;
	std::cout << "start to read point ....." << std::endl;
	PointXYZ p;
	if ((data_columns_type == "x y z") && (data_type == "ascii")){
		//讀取點座標記錄
		while (!fin.eof()){
			fin >> p.x >> p.y >> p.z;
			if (fin.peek() == EOF){
				break;
			}
			cloud.push_back(p);
		}
	}else{
		std::cout << "data_type = binary, read failed!" << std::endl;
    }
    ////////////////////////////////////////////////////////////
	//點座標輸出txt文字
	std::cout << "start to write point to txt....." << std::endl;
	std::ofstream out(foutname);
	for (size_t i = 0; i < points.size(); ++i)
	{
		out << std::setiosflags(std::ios::fixed) << std::setprecision(7)
			<< points.at(i).x << " "
			<< points.at(i).y << " "
			<< points.at(i).z << std::endl;
	}
	std::cout << "write point to txt finished!" << std::endl;
}

int main()
{
	std::string finname = "ascii_pcd.pcd";
	std::string foutame = "ascii_pcd.txt";
	std::vector<PointXYZ> points;
	readPCDfile(finname, points, foutame);

	system("pause");
	return 0;
}
 

2.執行結果：

3.總結

1. string中的find()函式，功能：查詢第一次出現的目標字串，如果存在則返回查詢到的第一個字元的索引，否則返回-1。
2. string中的substr(pos, n)函式，功能：返回一個string，包含pos位置開始的n個字元的拷貝（pos的預設值是0，n的預設值是s.size() - pos，即不加引數會預設拷貝整個s）。
3. string s.c_str()函式，功能：把string轉化成const char*，返回一個指向正規C字串的指標常量。
4. int atoi(const char *nptr)，功能：字串轉換成整型數。