# 2. Prerequisites
We have tested the library in **Ubuntu 12.04**, **14.04** and **16.04**, but it should be easy to compile in other platforms. A powerful computer (e.g. i7) will ensure real-time performance and provide more stable and accurate results.

## C++11 or C++0x Compiler
We use the new thread and chrono functionalities of C++11.

## Pangolin
We use [Pangolin](https://github.com/stevenlovegrove/Pangolin) for visualization and user interface. Dowload and install instructions can be found at: https://github.com/stevenlovegrove/Pangolin.

## OpenCV
We use [OpenCV](http://opencv.org) to manipulate images and features. Dowload and install instructions can be found at: http://opencv.org. **Required at leat 2.4.3. Tested with OpenCV 2.4.11 and OpenCV 3.2**.

## Eigen3
Required by g2o (see below). Download and install instructions can be found at: http://eigen.tuxfamily.org. **Required at least 3.1.0**.

## DBoW2 and g2o (Included in Thirdparty folder)
We use modified versions of the [DBoW2](https://github.com/dorian3d/DBoW2) library to perform place recognition and [g2o](https://github.com/RainerKuemmerle/g2o) library to perform non-linear optimizations. Both modified libraries (which are BSD) are included in the *Thirdparty* folder.

## ROS (optional)
We provide some examples to process the live input of a monocular, stereo or RGB-D camera using [ROS](ros.org). Building these examples is optional. In case you want to use ROS, a version Hydro or newer is needed.

相应依赖的安装已有很多先例，在此不做赘述。

编译

不使用ROS的编译:

cd ORB_SALM2  
chmod +x build.sh
./build.sh

使用ROS的编译：

1. 下载源代码并解压

把ORB_SALM2解压到工作空间的源文件下/catkin_ws/src中。（工作空间catkin_ws提前创建）

2. catkin_make

在catkin_ws中执行catkin_make

cd ~/catkin_ws/
catkin_make

3. 添加环境变量:

环境变量一个是source ~/.../devel/setup.bash，另一个是

export ROS_PACKAGE_PATH=${ROS_PACKAGE_PATH}:PATH/ORB_SLAM2/Examples/ROS。

其中，~/.../devel/setup.bash可以写入~/.bashrc中。

写入方法：

export ROS_PACKAGE_PATH=${ROS_PACKAGE_PATH}:PATH/ORB_SLAM2/Examples/ROS

echo "source ~/catkin_ws/devel/setup.bash" >> ~/.bashrc
source ~/.bashrc

其中，“PATH/ORB_SLAM2/Examples/ROS”等路径根据实际情况修改。

或者使用文本编辑器gedit或者vim编辑 ~/.bashrc

在终端中输入：
sudo gedit ~/.bashrc

使用gedit打开 ~/.bashrc，弹出文本编辑页面；
在文档末尾，追加：
export ROS_PACKAGE_PATH=${ROS_PACKAGE_PATH}:PATH/ORB_SLAM2/Examples/ROS
source ~/catkin_ws/devel/setup.bash

其中，“PATH/ORB_SLAM2/Examples/ROS”等路径根据实际情况修改。

4. ./build_ros.sh编译

使用ORB_SLAM2源文件文件夹的./build_ros.sh进行编译，先对其赋权，再执行它：

chmod +x build_ros.sh
./build_ros.sh

运行数据集

启动三个终端，分别用于开启master、运行ORB_SLAM2的可执行程序、播放rosbag。

以单目为例。

1. 开启master

启动一个终端，执行roscore：

roscore

开启master

2. 运行ORB_SLAM2的可执行程序

再启动一个终端，运行ORB_SLAM2的可执行程序，执行rosrun：

rosrun ORB_SLAM2 Mono PATH_TO_VOCABULARY PATH_TO_SETTINGS_FILE
##PATH_TO_VOCABULARY:    算法参数文件。形如/PATH/Vocabulary/ORBvoc.txt:
##PATH_TO_SETTINGS_FILE：相机参数设置文件，形如 /PATH/Examples/ROS/ORB_SLAM2/Asus.yaml

其中，“PATH_TO_VOCABULARY”等路径根据实际情况修改。

以我为例，运行KITTI00-02的数据集：

 rosrun ORB_SLAM2 Mono Vocabulary/ORBvoc.txt Examples/Monocular/KITTI00-02.yaml

此时，弹出ORB_SLAM2可执行程序的两个界面。

3. 播放rosbag

再启动一个终端，播放rosbag，执行rosbag play：

rosbag play xxx.bag

播放rosbag。

topic重映射

需要注意的是，对于自己的数据集，可能存在数据集的topic话题和ORB_SLAM2用于接受相机数据的topic话题不一致。如果不一致，程序的两个界面将不会有计算结果，不会有变化。因此，需要将二者对应。

比如，ORB_SLAM2用于接受相机数据的topic话题为 `/camera/image_raw`，而我的数据集中相机的topic话题为“kitti/camera_color_left/image_raw”，需要将二者对应，可以再播放数据集时，追加参数：

rosbag play xxx.bag /kitti/camera_color_left/image_raw:=/camera/image_raw

至此， ORB_SLAM2程序的两个界面将出现计算结果。

结果

以我为例：

参考 ORB_SLAM2的README.md：

# 4. Monocular Examples

## KITTI Dataset

1. Download the dataset (grayscale images) from http://www.cvlibs.net/datasets/kitti/eval_odometry.php

2. Execute the following command. Change `KITTIX.yaml`by KITTI00-02.yaml, KITTI03.yaml or KITTI04-12.yaml for sequence 0 to 2, 3, and 4 to 12 respectively. Change `PATH_TO_DATASET_FOLDER` to the uncompressed dataset folder. Change `SEQUENCE_NUMBER` to 00, 01, 02,.., 11.
```
./Examples/Monocular/mono_kitti Vocabulary/ORBvoc.txt Examples/Monocular/KITTIX.yaml PATH_TO_DATASET_FOLDER/dataset/sequences/SEQUENCE_NUMBER
```

# 7. ROS Examples

### Building the nodes for mono, monoAR, stereo and RGB-D
1. Add the path including *Examples/ROS/ORB_SLAM2* to the ROS_PACKAGE_PATH environment variable. Open .bashrc file and add at the end the following line. Replace PATH by the folder where you cloned ORB_SLAM2:

```
export ROS_PACKAGE_PATH=${ROS_PACKAGE_PATH}:PATH/ORB_SLAM2/Examples/ROS
```

2. Execute `build_ros.sh` script:

```
chmod +x build_ros.sh
./build_ros.sh
```

### Running Monocular Node
For a monocular input from topic `/camera/image_raw` run node ORB_SLAM2/Mono. You will need to provide the vocabulary file and a settings file. See the monocular examples above.

```
rosrun ORB_SLAM2 Mono PATH_TO_VOCABULARY PATH_TO_SETTINGS_FILE

报错

libboost_system

./build_ros.sh编译时报错：/usr/lib/x86_64-linux-gnu/libboost_system.so: error adding symbols: DSO missing from command
在Example/ROS/ORB_SLAM2/文件夹中的CMakeLists.txt 里面set()上加"-lboost_system"，即

set(LIBS 
${OpenCV_LIBS} 
${EIGEN3_LIBS}
${Pangolin_LIBRARIES}
${PROJECT_SOURCE_DIR}/../../../Thirdparty/DBoW2/lib/libDBoW2.so
${PROJECT_SOURCE_DIR}/../../../Thirdparty/g2o/lib/libg2o.so
${PROJECT_SOURCE_DIR}/../../../lib/libORB_SLAM2.so
##添加：
-lboost_system
)

链接master失败

[ERROR] [1682320579.511743459]: [registerPublisher] Failed to contact master at [localhost:11311]. Retrying...

提示需要启动ROS master，即在程序运行之初，需要先启动一个终端，执行“roscore”。

topic需要对应

kitti数据集中相机数据

rosbag play xxx.bag,同时把xxx.bag的topic /kitti/camera_color_left/image_raw对应为/camera/image_raw

要在Ros中播放一个bag文件并将其topic重映射到另一个名称，可以使用以下命令：

rosbag play xxx.bag /kitti/camera_color_left/image_raw:=/camera/image_raw

这将播放名为"xxx.bag"的bag文件，并将其topic "/kitti/camera_color_left/image_raw" 重映射到 "/camera/image_raw"。这将使您能够在Ros中使用 "/camera/image_raw" topic 来访问bag文件中的数据。

ORB_SLAM2的ROS运行kitti数据集

目的

环境

安装相应依赖

编译