OriginBot源码学习之摄像头驱动

这篇博客主要记录自己对于OriginBot-相机驱动与可视化代码的学习与理解，我会注释写在代码文件中。

在文档中，提供了两种驱动摄像头的方法：一个启动之后可以通过页面实时展示画面和人体检测算法的结果，另一种方法启动之后只是通过一个话题来发布图像数据。

可以通过浏览器查看的启动方式

文档里面说的很清楚，用以下命令启动：

ros2 launch originbot_bringup camera_websoket_display.launch.py
           

启动之后用浏览器打开 http://IP:8000 即可，

这个命令最后执行的代码是originbot.originbot_bringup.launch.camera_websoket_display.launch.py, 具体内容如下：

import os

from launch import LaunchDescription
from launch_ros.actions import Node

from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
from ament_index_python import get_package_share_directory
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration


def generate_launch_description():
    mipi_cam_device_arg = DeclareLaunchArgument(
        'device',
        default_value='GC4663',
        description='mipi camera device')

    # 这里是实际启动摄像头的Node，最终执行的事mipi_cam.launch.py,会在下面单独解释这个代码
    mipi_node = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(
                get_package_share_directory('mipi_cam'),
                'launch/mipi_cam.launch.py')),
        launch_arguments={
            'mipi_image_width': '960',
            'mipi_image_height': '544',
            'mipi_io_method': 'shared_mem',
            'mipi_video_device': LaunchConfiguration('device')
        }.items()
    )

    # nv12->jpeg
    # 这里调用了TogetheROS.Bot的图像编解码模块，目的是为了提升性能，具体参考：
    # https://developer.horizon.cc/documents_tros/quick_demo/hobot_codec
    jpeg_codec_node = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(
                get_package_share_directory('hobot_codec'),
                'launch/hobot_codec_encode.launch.py')),
        launch_arguments={
            'codec_in_mode': 'shared_mem',
            'codec_out_mode': 'ros',
            'codec_sub_topic': '/hbmem_img',
            'codec_pub_topic': '/image'
        }.items()
    )

    # web
    # 这个就是启动web的部分，实际上背后是一个Nginx静态服务器，
    # 订阅了image来展示图片，订阅了smart_topic来获取人体检测的数据
    # 这里最后是执行了websocket.laucn.py这个代码，下面再详细解释
    web_smart_topic_arg = DeclareLaunchArgument(
        'smart_topic',
        default_value='/hobot_mono2d_body_detection',
        description='websocket smart topic')
    web_node = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(
                get_package_share_directory('websocket'),
                'launch/websocket.launch.py')),
        launch_arguments={
            'websocket_image_topic': '/image',
            'websocket_smart_topic': LaunchConfiguration('smart_topic')
        }.items()
    )

    # mono2d body detection
    # TogetheROS.Bot的人体检测功能，
    # 会订阅/image_raw或者/hbmem_img的图片数据来做检测，
    # 然后把检测结果发布到hobot_mono2d_body_detection，
    # 我在https://www.guyuehome.com/45835里面有用到这个模块，也有相对详细的介绍，可以查看
    # 源码和官方文档在：https://developer.horizon.cc/documents_tros/quick_demo/hobot_codec
    mono2d_body_pub_topic_arg = DeclareLaunchArgument(
        'mono2d_body_pub_topic',
        default_value='/hobot_mono2d_body_detection',
        description='mono2d body ai message publish topic')
    mono2d_body_det_node = Node(
        package='mono2d_body_detection',
        executable='mono2d_body_detection',
        output='screen',
        parameters=[
            {"ai_msg_pub_topic_name": LaunchConfiguration(
                'mono2d_body_pub_topic')}
        ],
        arguments=['--ros-args', '--log-level', 'warn']
    )

    return LaunchDescription([
        mipi_cam_device_arg,
        # image publish
        mipi_node,
        # image codec
        jpeg_codec_node,
        # body detection
        mono2d_body_pub_topic_arg,
        mono2d_body_det_node,
        # web display
        web_smart_topic_arg,
        web_node
    ])           

上面的代码里面调用了mipi_cam.launch.py和 websocket.launch.py, 现在分别来介绍。

以下是originbot.mipi_cam.launch.mipi_cam.launch.py的内容：

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node


def generate_launch_description():
    return LaunchDescription([
        DeclareLaunchArgument(
            'mipi_camera_calibration_file_path',
            default_value='/userdata/dev_ws/src/origineye/mipi_cam/config/SC132GS_calibration.yaml',
            description='mipi camera calibration file path'),
        DeclareLaunchArgument(
            'mipi_out_format',
            default_value='nv12',
            description='mipi camera out format'),
        DeclareLaunchArgument(
            'mipi_image_width',
            default_value='1088',
            description='mipi camera out image width'),
        DeclareLaunchArgument(
            'mipi_image_height',
            default_value='1280',
            description='mipi camera out image height'),
        DeclareLaunchArgument(
            'mipi_io_method',
            default_value='shared_mem',
            description='mipi camera out io_method'),
        DeclareLaunchArgument(
            'mipi_video_device',
            default_value='F37',
            description='mipi camera device'),
        # 启动图片发布pkg
        Node(
            package='mipi_cam',
            executable='mipi_cam',
            output='screen',
            parameters=[
                {"camera_calibration_file_path": LaunchConfiguration(
                    'mipi_camera_calibration_file_path')},
                {"out_format": LaunchConfiguration('mipi_out_format')},
                {"image_width": LaunchConfiguration('mipi_image_width')},
                {"image_height": LaunchConfiguration('mipi_image_height')},
                {"io_method": LaunchConfiguration('mipi_io_method')},
                {"video_device": LaunchConfiguration('mipi_video_device')},
                {"rotate_degree": 90},
            ],
            arguments=['--ros-args', '--log-level', 'error']
        )
    ])           

这段代码其实也很简单，就是一些参数声明，但是如果使用了OriginBot一段时间的小伙伴应该记得，小车启动摄像头后，会通过一个叫做/image_raw的话题发布图像数据，这个话题在这里没有提到。

这一部分在originbot.mipi_cam.src.mipi_cam_node.cpp 里面的236行， 函数如下：

点击OriginBot源码学习之摄像头驱动 - 古月居可查看全文