我对点云世界还很陌生。此外，我在 C++ 方面的经验并不多。我需要阅读 .las 文件并使用 pcl 库处理它们。这是我需要读取的数据集中的示例文件。我关注了这个 youtube 视频。但是，由于我要读取的文件是 1.3 版，因此我按照相应的规范文件定义了标题字段，并使用了“数据记录格式 3”，这是文件标题中提到的数据记录格式。
这是我对标题和数据记录格式的定义：
#pragma once
#include <string>
#include <vector>
struct float4
{
float x, y, z, intensity;
};
class PointCloud
{
public:
uint32_t getVertsCount();
float4* getVertsData();
template<typename PointT>
typename pcl::PointCloud<PointT>::Ptr read(const std::string& path);//void read(const std::string &path);
private:
std::vector<float4> verts;
#pragma pack(1)
struct Header
{
char magic[4];
uint16_t fileSourceID;
uint16_t globalEncoding;
uint32_t guidData1;
uint16_t guidData2;
uint16_t guidData3;
uint8_t guidData4[8];
uint8_t versionMaj, versionMin;
char systemIdentifier[32];
char genSoftware[32];
uint16_t creationDay, creationYear;
uint16_t headerSize;
uint32_t pointDataOffset;
uint32_t numVarLenRecords;
uint8_t pointDataRecordFormat;
uint16_t pointDataRecordLen;
uint32_t numberOfPoints;
uint32_t numPointsByReturn[5];
double scaleX, scaleY, scaleZ;
double offsetX, offsetY, offsetZ;
double maxX, minX, maxY, minY, maxZ, minZ;
uint64_t waveform;
};
//#pragma pack(1)
struct PointRecord3
{
uint32_t x, y, z;
uint16_t intensity;
uint8_t flags;
uint8_t classification;
uint8_t scanAngleRank;
uint8_t userData;
uint16_t pointSourceId;
double gpsTime;
uint16_t red;
uint16_t green;
uint16_t blue;
};
};
我使用以下代码读取点数据，但未能获得正确的点：
template<typename PointT>
typename pcl::PointCloud<PointT>::Ptr PointCloud::read(const string& path)
{
ifstream inf(path, ios::binary);
typename pcl::PointCloud<PointT>::Ptr lasCloud(new pcl::PointCloud<PointT>);
if (inf.is_open())
{
Header header;
inf.read((char*)&header, sizeof(header));
cout << "Signature: " << header.magic << endl;
cout << "Source ID: " << int(header.fileSourceID) << endl;
cout << "Global Encoding: " << int(header.globalEncoding) << endl;
cout << "Guid 1: " << int(header.guidData1) << endl;
cout << "Guid 2: " << int(header.guidData2) << endl;
cout << "Guid 3: " << int(header.guidData3) << endl;
cout << "Guid 4: " << header.guidData4 << endl;
cout << (int)header.versionMaj << '.' << (int)header.versionMin << endl;
cout << "Sys Identifier: " << header.systemIdentifier << endl;
cout << "Gen Software: " << header.genSoftware << endl;
cout << "Creation Day: " << header.creationDay << endl;
cout << "Creation Year: " << header.creationYear << endl;
cout << header.headerSize << " == " << sizeof(header) << endl;
cout << "Point Data Offset: " << header.pointDataOffset << endl;
cout << "Number of Variable Len Records: " << header.numVarLenRecords << endl;
cout << "point Data Record Format: " << header.pointDataRecordFormat << endl;
cout << "point Data Record Len: " << header.pointDataRecordLen << endl;
cout << "Number of Points: " << header.numberOfPoints << endl;
cout << "Number of Points by Return: " << header.numPointsByReturn << endl;
cout << "Scales: " << header.scaleX << ", " << header.scaleY << ", " << header.scaleZ << endl;
cout << "Offsets: " << header.offsetX << ", " << header.offsetY << ", " << header.offsetZ << endl;
cout << "Xmin = " << header.minX << ", Ymin = " << header.minY << ", Zmin = " << header.minZ << endl;
cout << "Xmax = " << header.maxX << ", Ymax = " << header.maxY << ", Zmax = " << header.maxZ << endl;
cout << "Waveform: "<<header.waveform << endl;
assert(header.versionMaj == 1 && header.versionMin == 3);
//assert(header.headerSize == sizeof(header));
assert(header.pointDataRecordFormat == 3);
//inf.seekg(header.pointDataOffset);
inf.seekg(sizeof(header));
//inf.seekg(header.pointDataOffset+sizeof(header.waveform));
for (uint32_t i = 0; i < header.numberOfPoints; i++)
{
//PointRecord1* points = new PointRecord1[header.numberOfPoints];
PointRecord3 point;
//inf.read((char*)(points + i), sizeof(PointRecord1));
//inf.read((char*)&point, sizeof(PointRecord1));
inf.read((char*)&point, sizeof(PointRecord3));
PointT cloudPoint;
cloudPoint.x = (float)(point.x * header.scaleX) + header.offsetX;
cloudPoint.y = (float)(point.y * header.scaleY) + header.offsetY;
cloudPoint.z = (float)(point.z * header.scaleZ) + header.offsetZ;
cloudPoint.intensity = (float)(point.intensity) / 65536.0;
lasCloud->points.push_back(cloudPoint);
}
if (!inf.good())
throw runtime_error("Reading went wrong!");
}
else
{
throw runtime_error("Can't find any!");
}
lasCloud->width = lasCloud->points.size();
lasCloud->height = 1;
lasCloud->is_dense = true;
std::cout << "Cloud size = " << lasCloud->points.size() << endl;
return lasCloud;
}
int main (int argc, char** argv)
{
std::cout << "starting enviroment" << std::endl;
pcl::visualization::PCLVisualizer::Ptr viewer (new pcl::visualization::PCLVisualizer ("3D Viewer"));
CameraAngle setAngle = FPS; //XY, FPS, Side, TopDown
initCamera(setAngle, viewer);
pcl::PointCloud<pcl::PointXYZI>::Ptr inputCloudI; //
PointCloud pcd;
inputCloudI=pcd.read<pcl::PointXYZI>("C:/Users/hedey/OneDrive/Documents/Research_papers/STDF/10_4231_MFQF-Q141/I-65/LiDAR/RoadSurface/NB/20180524_I65_NB_RoadSurface_1_50.5.las");
std::cout << "Cloud size = " << inputCloudI->points.size() << endl;
renderPointCloud(viewer, inputCloudI, "lasCloud");
while (!viewer->wasStopped())
{
viewer->spinOnce();
}
}
我注意到了一个问题。标头大小定义为 227（这是标头大小字段的值）。但是，在报头的末尾有一个名为“波形数据包记录开始”的 8 字节字段，如果包含在报头定义中，则报头大小为 235 字节。此外，用于在 youtube 视频中查找点数据的 pointDataOffset 字段指向 227 字节。当我用它来寻找积分数据时，我得到了不合理的积分值。我的目标是处理这个点云并使用 pcl 云显示它，但我无法正确读取这些点。