OriginBot源碼學習之攝像頭驅動

這篇部落客要記錄自己對于OriginBot-相機驅動與可視化代碼的學習與了解，我會注釋寫在代碼檔案中。

在文檔中，提供了兩種驅動攝像頭的方法：一個啟動之後可以通過頁面實時展示畫面和人體檢測算法的結果，另一種方法啟動之後隻是通過一個話題來釋出圖像資料。

可以通過浏覽器檢視的啟動方式

文檔裡面說的很清楚，用以下指令啟動：

ros2 launch originbot_bringup camera_websoket_display.launch.py
           

啟動之後用浏覽器打開 http://IP:8000 即可，

這個指令最後執行的代碼是originbot.originbot_bringup.launch.camera_websoket_display.launch.py, 具體内容如下：

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')

    # 這裡是實際啟動攝像頭的Node，最終執行的事mipi_cam.launch.py,會在下面單獨解釋這個代碼
    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
    # 這裡調用了TogetheROS.Bot的圖像編解碼子產品，目的是為了提升性能，具體參考：
    # 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
    # 這個就是啟動web的部分，實際上背後是一個Nginx靜态伺服器，
    # 訂閱了image來展示圖檔，訂閱了smart_topic來擷取人體檢測的資料
    # 這裡最後是執行了websocket.laucn.py這個代碼，下面再詳細解釋
    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的人體檢測功能，
    # 會訂閱/image_raw或者/hbmem_img的圖檔資料來做檢測，
    # 然後把檢測結果釋出到hobot_mono2d_body_detection，
    # 我在https://www.guyuehome.com/45835裡面有用到這個子產品，也有相對詳細的介紹，可以檢視
    # 源碼和官方文檔在：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
    ])           

上面的代碼裡面調用了mipi_cam.launch.py和 websocket.launch.py, 現在分别來介紹。

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'),
        # 啟動圖檔釋出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']
        )
    ])           

這段代碼其實也很簡單，就是一些參數聲明，但是如果使用了OriginBot一段時間的小夥伴應該記得，小車啟動攝像頭後，會通過一個叫做/image_raw的話題釋出圖像資料，這個話題在這裡沒有提到。

這一部分在originbot.mipi_cam.src.mipi_cam_node.cpp 裡面的236行， 函數如下：

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