usb_cam的ROS2甜点

最近收到一些反馈，不多但是都非常有价值，感谢反馈的朋友们。关于ROS2的实践和应用类型课程已经开发完成，ROS1最终版Noetic也会出一版纪念版镜像配合教程，但博客更新主要集中于ROS2的相关应用。

usb_cam这是非常典型有价值的摄像头包。主要有两个：

• ros2_usb_camera-foxy-devel
• usb_cam-ros2

代码差异还是有不少的。

推荐使用usb_cam。

•  ros2 launch usb_cam demo_launch.py 

效果如下：

这个是640*480

如果需要1280*720，需要修改如下：

usb_cam_node.cpp

  

   

    

     

    
    

     
  // declare params
     
    
   

    

     

    
    

     
  this->declare_parameter("camera_name", "default_cam");
     
    
   

    

     

    
    

     
  this->declare_parameter("camera_info_url", "");
     
    
   

    

     

    
    

     
  this->declare_parameter("framerate", 10.0);
     
    
   

    

     

    
    

     
  this->declare_parameter("frame_id", "default_cam");
     
    
   

    

     

    
    

     
  this->declare_parameter("image_height", 720);
     
    
   

    

     

    
    

     
  this->declare_parameter("image_width", 1280);
     
    
   

    

     

    
    

     
  this->declare_parameter("io_method", "mmap");
     
    
   

    

     

    
    

     
  this->declare_parameter("pixel_format", "yuyv");
     
    
   

    

     

    
    

     
  this->declare_parameter("video_device", "/dev/video0");
     
    
  
 

这样就可以吗？应该是不行的，还需要的操作如下：

先看下启动文件launch

  

   

    

     

    
    

     

      # Copyright 2018 Lucas Walter
     
    
   

    

     

    
    

     

      # All rights reserved.
     
    
   

    

     

    
    

     

      #
     
    
   

    

     

    
    

     

      # Software License Agreement (BSD License 2.0)
     
    
   

    

     

    
    

     

      #
     
    
   

    

     

    
    

     

      # Redistribution and use in source and binary forms, with or without
     
    
   

    

     

    
    

     

      # modification, are permitted provided that the following conditions
     
    
   

    

     

    
    

     

      # are met:
     
    
   

    

     

    
    

     

      #
     
    
   

    

     

    
    

     

      # * Redistributions of source code must retain the above copyright
     
    
   

    

     

    
    

     

      # notice, this list of conditions and the following disclaimer.
     
    
   

    

     

    
    

     

      # * Redistributions in binary form must reproduce the above
     
    
   

    

     

    
    

     

      # copyright notice, this list of conditions and the following
     
    
   

    

     

    
    

     

      # disclaimer in the documentation and/or other materials provided
     
    
   

    

     

    
    

     

      # with the distribution.
     
    
   

    

     

    
    

     

      # * Neither the name of Lucas Walter nor the names of its
     
    
   

    

     

    
    

     

      # contributors may be used to endorse or promote products derived
     
    
   

    

     

    
    

     

      # from this software without specific prior written permission.
     
    
   

    

     

    
    

     

      #
     
    
   

    

     

    
    

     

      # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     
    
   

    

     

    
    

     

      # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     
    
   

    

     

    
    

     

      # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     
    
   

    

     

    
    

     

      # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     
    
   

    

     

    
    

     

      # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     
    
   

    

     

    
    

     

      # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     
    
   

    

     

    
    

     

      # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     
    
   

    

     

    
    

     

      # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
     
    
   

    

     

    
    

     

      # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     
    
   

    

     

    
    

     

      # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
     
    
   

    

     

    
    

     

      # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     
    
   

    

     

    
    

     

      # POSSIBILITY OF SUCH DAMAGE.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      import argparse
     
    
   

    

     

    
    

     

      from launch import LaunchDescription
     
    
   

    

     

    
    

     

      from launch_ros.actions import Node
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      import os
     
    
   

    

     

    
    

     

      import sys
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      from ament_index_python.packages import get_package_share_directory
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      def generate_launch_description():
     
    
   

    

     

    
    

     

          ld = LaunchDescription()
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          parser = argparse.ArgumentParser(description='usb_cam demo')
     
    
   

    

     

    
    

     

          parser.add_argument('-n', '--node-name', dest='node_name', type=str,
     
    
   

    

     

    
    

     

                              help='name for device', default='usb_cam')
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          args, unknown = parser.parse_known_args(sys.argv[4:])
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          usb_cam_dir = get_package_share_directory('usb_cam')
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    # get path to params file
     
    
   

    

     

    
    

     

          params_path = os.path.join(
     
    
   

    

     

    
    

     

              usb_cam_dir,
     
    
   

    

     

    
    

     
        'config',
     
    
   

    

     

    
    

     
        'params.yaml'
     
    
   

    

     

    
    

     

          )
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          node_name = args.node_name
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          print(params_path)
     
    
   

    

     

    
    

     

          ld.add_action(Node(
     
    
   

    

     

    
    

     

              package='usb_cam', executable='usb_cam_node_exe', output='screen',
     
    
   

    

     

    
    

     

              name=node_name,
     
    
   

    

     

    
    

     
        # namespace=ns,
     
    
   

    

     

    
    

     

              parameters=[params_path]
     
    
   

    

     

    
    

     

              ))
     
    
   

    

     

    
    

     

          ld.add_action(Node(
     
    
   

    

     

    
    

     

              package='usb_cam', executable='show_image.py', output='screen',
     
    
   

    

     

    
    

     
        # namespace=ns,
     
    
   

    

     

    
    

     
        # arguments=[image_manip_dir + "/data/mosaic.jpg"])
     
    
   

    

     

    
    

     
        # remappings=[('image_in', 'image_raw')]
     
    
   

    

     

    
    

     

              ))
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    return ld
     
    
  
 

注意到如下这一段：

  

   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    # get path to params file
     
    
   

    

     

    
    

     

          params_path = os.path.join(
     
    
   

    

     

    
    

     

              usb_cam_dir,
     
    
   

    

     

    
    

     
        'config',
     
    
   

    

     

    
    

     
        'params.yaml'
     
    
   

    

     

    
    

     

          )
     
    
   

    

     

    
    

     
 
     
    
  
 

需要修改啦：

camera_info.yaml

  

   

    

     

    
    

     

      image_width: 1280
     
    
   

    

     

    
    

     

      image_height: 720
     
    
   

    

     

    
    

     

      camera_name: test_camera
     
    
   

    

     

    
    

     

      camera_matrix:
     
    
   

    

     

    
    

     

        rows: 3
     
    
   

    

     

    
    

     

        cols: 3
     
    
   

    

     

    
    

     

        data: [438.783367, 0.000000, 305.593336, 0.000000, 437.302876, 243.738352, 0.000000, 0.000000, 1.000000]
     
    
   

    

     

    
    

     

      distortion_model: plumb_bob
     
    
   

    

     

    
    

     

      distortion_coefficients:
     
    
   

    

     

    
    

     

        rows: 1
     
    
   

    

     

    
    

     

        cols: 5
     
    
   

    

     

    
    

     

        data: [-0.361976, 0.110510, 0.001014, 0.000505, 0.000000]
     
    
   

    

     

    
    

     

      rectification_matrix:
     
    
   

    

     

    
    

     

        rows: 3
     
    
   

    

     

    
    

     

        cols: 3
     
    
   

    

     

    
    

     

        data: [0.999978, 0.002789, -0.006046, -0.002816, 0.999986, -0.004401, 0.006034, 0.004417, 0.999972]
     
    
   

    

     

    
    

     

      projection_matrix:
     
    
   

    

     

    
    

     

        rows: 3
     
    
   

    

     

    
    

     

        cols: 4
     
    
   

    

     

    
    

     

        data: [393.653800, 0.000000, 322.797939, 0.000000, 0.000000, 393.653800, 241.090902, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000]
     
    
  
 

params.yaml

  

   

    

     

    
    

     

      /**:
     
    
   

    

     

    
    

     

          ros__parameters:
     
    
   

    

     

    
    

     

            video_device: "/dev/video0"
     
    
   

    

     

    
    

     

            framerate: 30.0
     
    
   

    

     

    
    

     

            io_method: "mmap"
     
    
   

    

     

    
    

     

            frame_id: "camera"
     
    
   

    

     

    
    

     

            pixel_format: "yuyv"
     
    
   

    

     

    
    

     

            image_width: 1280
     
    
   

    

     

    
    

     

            image_height: 720
     
    
   

    

     

    
    

     

            camera_name: "test_camera"
     
    
   

    

     

    
    

     

            camera_info_url: "package://usb_cam/config/camera_info.yaml"
     
    
  
 

参数合适吗？不管，效果还是有的：

然后，就可以愉快玩耍各种图形处理算法啦，欢乐不^_^

文章来源: zhangrelay.blog.csdn.net，作者：zhangrelay，版权归原作者所有，如需转载，请联系作者。

原文链接：zhangrelay.blog.csdn.net/article/details/120214789