n.71 可视化影像数据（ros2）rviz

大家好，我是讯享网，很高兴认识大家。

1.创建工作区

ros2 pkg create my_package --build-type ament_cmake --dependencies rclcpp

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然后创建一个launch文件夹，内部导入simulation.launch.py的launch.py启动文件

讯享网# Copyright 2019 Louise Poubel # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """Launch Gazebo with a world that has Dolly, as well as the follow node.""" import os from ament_index_python.packages import get_package_share_directory from launch import LaunchDescription from launch.actions import DeclareLaunchArgument from launch.actions import IncludeLaunchDescription from launch.conditions import IfCondition from launch.launch_description_sources import PythonLaunchDescriptionSource from launch.substitutions import LaunchConfiguration from launch_ros.actions import Node from launch.substitutions import ThisLaunchFileDir def generate_launch_description(): pkg_gazebo_ros = get_package_share_directory('gazebo_ros') pkg_dolly_gazebo = get_package_share_directory('dolly_gazebo') pkg_my_package = get_package_share_directory('my_package') # Gazebo launch gazebo = IncludeLaunchDescription( PythonLaunchDescriptionSource( os.path.join(pkg_gazebo_ros, 'launch', 'gazebo.launch.py'), ) ) # Follow node follow = Node( package='dolly_follow', executable='dolly_follow', output='screen', remappings=[ ('cmd_vel', '/dolly/cmd_vel'), ('laser_scan', '/dolly/laser_scan') ] ) # RViz rviz = Node( package='rviz2', executable='rviz2', condition=IfCondition(LaunchConfiguration('rviz')) ) return LaunchDescription([ DeclareLaunchArgument( 'world', default_value=[os.path.join(pkg_dolly_gazebo, 'worlds', 'dolly_empty.world'), ''], description='SDF world file'), DeclareLaunchArgument('rviz', default_value='true', description='Open RViz.'), gazebo, follow, rviz ])

2.分析.launch.py代码

1.导入launch文件的包，默认就是这些。

import os from ament_index_python.packages import get_package_share_directory from launch import LaunchDescription from launch.actions import DeclareLaunchArgument from launch.actions import IncludeLaunchDescription from launch.conditions import IfCondition from launch.launch_description_sources import PythonLaunchDescriptionSource from launch.substitutions import LaunchConfiguration from launch_ros.actions import Node from launch.substitutions import ThisLaunchFileDir

2.要启动的部分

讯享网def generate_launch_description(): ... return LaunchDescription([ ])

3.导入要启动部分的文件夹路径

 pkg_gazebo_ros = get_package_share_directory('gazebo_ros') pkg_dolly_gazebo = get_package_share_directory('dolly_gazebo') pkg_my_package = get_package_share_directory('my_package')

4.添加gazebo的默认程序的节点

讯享网 # Gazebo launch gazebo = IncludeLaunchDescription( PythonLaunchDescriptionSource( os.path.join(pkg_gazebo_ros, 'launch', 'gazebo.launch.py'), ) )

5.添加主要的程序部分的节点

 # Follow node follow = Node( package='dolly_follow', executable='dolly_follow', output='screen', remappings=[ ('cmd_vel', '/dolly/cmd_vel'), ('laser_scan', '/dolly/laser_scan') ] )

6.·添加rviz部分的节点

讯享网 # RViz rviz = Node( package='rviz2', executable='rviz2', condition=IfCondition(LaunchConfiguration('rviz')) )

DeclareLaunchArgument( 'world', default_value=[os.path.join(pkg_dolly_gazebo, 'worlds', 'dolly_empty.world'), ''], description='SDF world file')

代表设定的启动时候的参数
两个设定参数的函数：
1.LaunchConfiguration： is local to the launch file and scoped.
2.DeclareLaunchArgument： allows you to expose the argument outside of your launch file. Allowing them to be listed, set, or marked as required when a user launches it from the command line (using ros2 launch) or when including it from another launch file (using IncludeLaunchDescription).
补充：
A LaunchConfiguration cannot be required to be set when launching or including and it is not possible to set it when launching from the command line. You can set a LaunchConfiguration before including another launch file, but an argument is better if you want it to be reused.
参考：https://answers.ros.org/question//ros2-what-is-different-between-declarelaunchargument-and-launchconfiguration/
这里，给’world’添加了两个参数，一个是default_value（从本launch文件外添加），另一个是description
然后启动这个world文件，因为return LaunchDescription
8.

讯享网 DeclareLaunchArgument('rviz', default_value='true', description='Open RViz.')

这里同样，给’rviz’添加了参数

```
 gazebo, follow, rviz 
```

运行这三部分。

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3.修改cmakelists

添加以下部分,只是编译launch.py文件的话，以下足够！牢记！！

讯享网install(DIRECTORY launch DESTINATION share/${ 
   PROJECT_NAME}/ )

4.编译即可

只是更改python文件，再进行编译的时候使用colcon build --symlink-install 即可
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5.添加主要项目部分

在这里插入图片描述
添加了dolly。
修改CMakeLists(My_package中的)
添加：
find_package(ament_cmake REQUIRED)
find_package(geometry_msgs REQUIRED)
find_package(rclcpp REQUIRED)
find_package(sensor_msgs REQUIRED)