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【】 calculating trajectory error

2022-08-06 06:36:00 【small guest】

评估轨迹的误差

计算均方根误差
$\sqrt{\frac{1}{N} \sum_{1}^{N} ||log(T^{-1}_{ground,truth}T_{estimate,i})||^2_2}$

The format of the given data：

The following three groups of real data data,Corresponding timestamp is,平移,And the rotation of the quaternion said

1305031526.67210007 -0.0355094123046875154 -0.0070967674641926326 0.0100241180501300375 0.747064124448400424 0.448673366467715162 -0.443835884862102847 0.208799213344654372
1305031526.71219993 -0.0337215082682291722 -0.00720814225260424379 0.00152885084635434598 0.735554936692470185 0.468316402085190431 -0.441780989823346237 0.210874938473073842
1305031526.77220011 -0.0335672539713542939 -0.00830686082356790756 -0.0142845526529947753 -0.715793317510356131 -0.503173810000826283 0.436339717689256446 -0.209913540067406978

The following three groups are estimated data

1305031526.67147303 0 0 0 0 0 1 0
1305031526.70754695 0.00288319499999999986 -0.00466209999999999975 -0.00225430399999999994 0.0106974147769499078 0.00218949395434721002 0.999875286151759579 0.0114098017620960397
1305031526.77148104 0.0139789660000000007 -0.0130823169999999996 -0.0108695960000000005 0.0325266728104138744 0.00326054208123759126 0.998528028878688856 0.0432800180783373817

The brief analysis of the data shows,The time data is aligned,Effective digit is a number

代码编写流程

需要的库文件,Sophus,pangolin
读入数据,Whether the data really read
进行计算（From quaternions structureSE3）
Drawing visual contrast
Summary of theC++语言技巧
bug总结

代码如下

#include <iostream>
#include <fstream>
#include <vector>
//unistd.h为Linux/Unix系统中内置头文件,包含了许多系统服务的函数原型,例如read函数、write函数和getpid函数等.
//其作用相当于windows操作系统的"windows.h",是操作系统为用户提供的统一API接口,方便调用系统提供的一些服务.
#include <unistd.h>
#include <eigen3/Eigen/Core>
#include <pangolin/pangolin.h>
#include <sophus/se3.hpp>
using namespace std;
using namespace Sophus;

const string file_est = "/home/wpf/Test/study_cpp/chapter41/data/estimated.txt";
const string file_truth = "/home/wpf/Test/study_cpp/chapter41/data/groundtruth.txt";

//The return type is so long,So to define a return type
typedef vector<Sophus::SE3d,Eigen::aligned_allocator<Sophus::SE3d>> TrajectortyType;
TrajectortyType ReadTrajectory(const string &path);
//Drawing function just need into two paths array
void DrawTrajectory(const TrajectortyType &gt,const TrajectortyType &esti);

int main() {
    
    //第一步,读入数据
    TrajectortyType groundTruth = ReadTrajectory(file_truth);
    TrajectortyType estimated = ReadTrajectory(file_est);
    //使用vector中的算法
    assert(!groundTruth.empty() && !estimated.empty());
    assert(groundTruth.size() == estimated.size());
    //计算
    double rmse = 0;
    for (int i = 0; i < groundTruth.size(); ++i) {
    
        Sophus::SE3d p_est = estimated[i],p_tru = groundTruth[i];
        double error_1 = (p_tru.inverse()*p_est).log().norm();
        rmse += error_1*error_1;

    }
    rmse = rmse/groundTruth.size();
    rmse = sqrt(rmse);
    cout<<"RMSE:"<<rmse<<endl;
    //出图像
    DrawTrajectory(groundTruth,estimated);
    std::cout << "Hi,wpf!You're the best!" << std::endl;
    return 0;
}
TrajectortyType ReadTrajectory(const string &path){
    
    ifstream fin(path);
    TrajectortyType trajectorty;
    if(!fin){
    
        cerr<<"tracjectory"<<path <<" not found"<<endl;
        return trajectorty;
    }
    //如何读数据,数据格式的处理
    //getline是以‘\n’截断,不会忽略空格.
    //eof是以’空格‘或’\n’截断,Will ignore some indispensable space,如query"华为 9X"
    /** * * * */
    while(!fin.eof()){
    
        double time,tx,ty,tz,qx,qy,qz,qw;
        fin>>time>>tx>>ty>>tz>>qx>>qy>>qz>>qw;
        Sophus::SE3d p1(Eigen::Quaterniond(qw,qx,qy,qz),Eigen::Vector3d(tx,ty,tz));
        trajectorty.emplace_back(p1);
    }
    return trajectorty;
}
void DrawTrajectory(const TrajectortyType &gt, const TrajectortyType &esti) {
    
    // create pangolin window and plot the trajectory
    pangolin::CreateWindowAndBind("Trajectory Viewer", 1024, 768);
    //Three format
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    pangolin::OpenGlRenderState s_cam(
            pangolin::ProjectionMatrix(1024, 768, 500, 500, 512, 389, 0.1, 1000),
            pangolin::ModelViewLookAt(0, -0.1, -1.8, 0, 0, 0, 0.0, -1.0, 0.0)
    );

    pangolin::View &d_cam = pangolin::CreateDisplay()
            .SetBounds(0.0, 1.0, pangolin::Attach::Pix(175), 1.0, -1024.0f / 768.0f)
            .SetHandler(new pangolin::Handler3D(s_cam));


    while (pangolin::ShouldQuit() == false) {
    
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        d_cam.Activate(s_cam);
        glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

        glLineWidth(2);

        //Draw the real trajectory images,
        for (size_t i = 0; i < gt.size() - 1; i++) {
    
            glColor3f(0.0f, 0.0f, 1.0f);  // blue for ground truth
            glBegin(GL_LINES);
            //Access to data between the first and second,To get the translation vector between
            auto p1 = gt[i], p2 = gt[i + 1];
            glVertex3d(p1.translation()[0], p1.translation()[1], p1.translation()[2]);
            glVertex3d(p2.translation()[0], p2.translation()[1], p2.translation()[2]);
            glEnd();
        }
        //Draw the forecast track,同上
        for (size_t i = 0; i < esti.size() - 1; i++) {
    
            glColor3f(1.0f, 0.0f, 0.0f);  // red for estimated
            glBegin(GL_LINES);
            auto p1 = esti[i], p2 = esti[i + 1];
            glVertex3d(p1.translation()[0], p1.translation()[1], p1.translation()[2]);
            glVertex3d(p2.translation()[0], p2.translation()[1], p2.translation()[2]);
            glEnd();
        }
        pangolin::FinishFrame();
        usleep(5000);   // sleep 5 ms
    }
}

对应的CMakeList.txt如下：

cmake_minimum_required(VERSION 3.20)
set(CMAKE_CXX_STANDARD 14)
project(chapter41)
find_package(Pangolin REQUIRED)
# 由于SophusLibrary to depend onfmt库,所以安装Sophus之前要先安装fmt
find_package(fmt REQUIRED)
find_package(Sophus REQUIRED)
include_directories("usr/include/eigen3")
include_directories(${Pangolin_INCLUDE_DIRS})

add_executable(chapter41 main.cpp)

target_link_libraries(chapter41 ${Pangolin_LIBRARIES} Sophus::Sophus fmt::fmt)

C++Language skills

（1）文件的读写,

//getline是以‘\n’截断,不会忽略空格.
//eof是以’空格‘或’\n’截断,Will ignore some indispensable space,如query"华为 9X"

If the behavior at the end

使用

//方式一：getline读取
getline(fin, line); //逐行读取fin打开的文件,保存在line里.(分隔符为 \n)

If end with Spaces and the behavior,使用

while(!fin.eof) {  //当finOpen the file didn't finish read
  fin >> line;   //Will take the Spaces and the\nDelimited text intoline中
}

#include <fstream>
std::ifstream fin;        //定义输入文件流对象
fin.open("data/xxx.txt")    //Open the program under the relative path to a file,Additional parameters can also bestd::ios::in等各种
std::string line;  //File stream carrier,面向开发人员

//方式一：getline读取
getline(fin, line); //逐行读取fin打开的文件,保存在line里.(分隔符为 \n)

//方式二:!eof()
while(!fin.eof) {
        //当finOpen the file didn't finish read
  fin >> line;   //Will take the Spaces and the\nDelimited text intoline中
}