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
代码语言：javascript复制 // 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
代码语言：javascript复制# Copyright 2018 Lucas Walter
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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：
代码语言：javascript复制 # get path to params file
params_path = os.path.join(
usb_cam_dir,
'config',
'params.yaml'
)需要修改啦：
camera_info.yaml
代码语言：javascript复制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
代码语言：javascript复制/**:
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：
