ORB-SLAM代码详解之SLAM系统初始化

转载请注明出处：http://blog.youkuaiyun.com/c602273091/article/details/54933760

system.h

这里包含了整个SLAM系统所需要的一起，通过看这个文件可以对ORB-SLAM系统有什么有一个大概的了解。不过之前我们需要对于多线程了解一些基本的东西——信号量【1】和多线程【2】。

具体注释如下：

/**
* This file is part of ORB-SLAM2.
*
* Copyright (C) 2014-2016 Ra煤l Mur-Artal <raulmur at unizar dot es> (University of Zaragoza)
* For more information see <https://github.com/raulmur/ORB_SLAM2>
*
* ORB-SLAM2 is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* ORB-SLAM2 is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with ORB-SLAM2. If not, see <http://www.gnu.org/licenses/>.
*/


#ifndef SYSTEM_H
#define SYSTEM_H

#include<string>
#include<thread>
#include<opencv2/core/core.hpp>

#include "Tracking.h"
#include "FrameDrawer.h"
#include "MapDrawer.h"
#include "Map.h"
#include "LocalMapping.h"
#include "LoopClosing.h"
#include "KeyFrameDatabase.h"
#include "ORBVocabulary.h"
#include "Viewer.h"

namespace ORB_SLAM2
{

class Viewer; // 画图
class FrameDrawer; // 画每一帧
class Map; // 对map进行操作
class Tracking; // 追踪的过程
class LocalMapping; // 局部地图
class LoopClosing; // 闭环检测

class System
{
public:
    // Input sensor
    // 输入设备：单目、立体视觉、RGBD
    enum eSensor{
        MONOCULAR=0,
        STEREO=1,
        RGBD=2
    };

public:

    // Initialize the SLAM system. It launches the Local Mapping, Loop Closing and Viewer threads.
    // 对SLAM系统的初始化：包含局部地图、闭环检测、视图三个线程
    System(const string &strVocFile, const string &strSettingsFile, const eSensor sensor, const bool bUseViewer = true);

    // Proccess the given stereo frame. Images must be synchronized and rectified.
    // Input images: RGB (CV_8UC3) or grayscale (CV_8U). RGB is converted to grayscale.
    // Returns the camera pose (empty if tracking fails).
    cv::Mat TrackStereo(const cv::Mat &imLeft, const cv::Mat &imRight, const double &timestamp);

    // Process the given rgbd frame. Depthmap must be registered to the RGB frame.
    // Input image: RGB (CV_8UC3) or grayscale (CV_8U). RGB is converted to grayscale.
    // Input depthmap: Float (CV_32F).
    // Returns the camera pose (empty if tracking fails).
    cv::Mat TrackRGBD(const cv::Mat &im, const cv::Mat &depthmap, const double &timestamp);

    // Proccess the given monocular frame
    // Input images: RGB (CV_8UC3) or grayscale (CV_8U). RGB is converted to grayscale.
    // Returns the camera pose (empty if tracking fails).
    // 对单目的图片进行追踪
    cv::Mat TrackMonocular(const cv::Mat &im, const double &timestamp);

    // This stops local mapping thread (map building) and performs only camera tracking.
    // 暂停局部地图的构建，只进行追踪，这个名字很有迷惑性
    void ActivateLocalizationMode();
    // This resumes local mapping thread and performs SLAM again.
    // 重新开启局部地图的线程
    // 在这里使用的是mutex信号量的多线程编程
    void DeactivateLocalizationMode();

    // Reset the system (clear map)
    // 复位清楚地图
    void Reset();

    // All threads will be requested to finish.
    // It waits until all threads have finished.
    // This function must be called before saving the trajectory.
    // 等到所有线程结束任务的时候关闭每个线程
    void Shutdown();

    // Save camera trajectory in the TUM RGB-D dataset format.
    // Call first Shutdown()
    // See format details at: http://vision.in.tum.de/data/datasets/rgbd-dataset
    void SaveTrajectoryTUM(const string &filename);

    // Save keyframe poses in the TUM RGB-D dataset format.
    // Use this function in the monocular case.
    // Call first Shutdown()
    // See format details at: http://vision.in.tum.de/data/datasets/rgbd-dataset
    void SaveKeyFrameTrajectoryTUM(const string &filename);

    // Save camera trajectory in the KITTI dataset format.
    // Call first Shutdown()
    // See format details at: http://www.cvlibs.net/datasets/kitti/eval_odometry.php
    // kitti数据集的保存位姿的方法
    void SaveTrajectoryKITTI(const string &filename);

    // TODO: Save/Load functions
    // SaveMap(const string &filename);
    // LoadMap(const string &filename);

private:

    // Input sensor
    // 输入的传感器类型
    eSensor mSensor;

    // 用于特征匹配和闭环检测的字典
    // ORB vocabulary used for place recognition and feature matching.
    ORBVocabulary* mpVocabulary;

    // K