Ros2 Humble camera info url ignored when publishing from rtsp stream

Question

before I get started, I'd like to point out that I have done thorough research and studied all similar issues I could find. Unfortunately I didn't find a solution that worked for my problem.

I am working on a package that uses the Ros2 built in image_publisher_node from ros-perception. I use a python launch-file which subscribes to a rts-stream from an ip-camera:

import os

from ament_index_python.packages import get_package_share_directory

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


def generate_launch_description():
    use_sim_time = LaunchConfiguration('use_sim_time', default='false')
    camera_info_url = LaunchConfiguration('camera_info_url', default ='')
    return LaunchDescription([
        
        DeclareLaunchArgument(
            'camera_info_url',
            default_value='file://' + os.path.join(get_package_share_directory('marvin_data_collector'),'config','front_camera_info.yaml'),
            description='URL of the camera calibration file.'
            ),

        DeclareLaunchArgument(
            'use_sim_time',
            default_value='false',
            description='Use simulation clock if true'
            ),

        Node(
            package='image_publisher', executable='image_publisher_node', output='screen',
            arguments=['rtsp://admin:[email protected]:554/h264'],
            parameters=[{'camera_info_url': camera_info_url,
                        'use_sim_time': use_sim_time,
                        'publish_rate': 1.0,
                        'qos_overrides./parameter_events.publisher.depth': 10,
                        'qos_overrides./parameter_events.publisher.reliability': 'best_effort'}],
            remappings=[('__ns', '/front')]
            )
    ])

This works well enough, I get the image topics and the camera_info topic. However, it appears that the camera_info_url I use gets ignored.

This is the front_camera_info.yaml I use:

image_width: 1920
image_height: 1080
camera_name: narrow_stereo
camera_matrix:
  rows: 3
  cols: 3
  data: [2154.84924,    0.     , 1067.48426,
            0.     , 2183.19372,  486.52951,
            0.     ,    0.     ,    1.     ]
distortion_model: plumb_bob
distortion_coefficients:
  rows: 1
  cols: 5
  data: [-0.419139, 0.235887, 0.008504, -0.008708, 0.000000]
rectification_matrix:
  rows: 3
  cols: 3
  data: [1., 0., 0.,
        0., 1., 0.,
        0., 0., 1.]
projection_matrix:
  rows: 3
  cols: 4
  data: [1970.31262,    0.     , 1071.2062 ,    0.     ,
            0.     , 2125.4436 ,  487.01673,    0.     ,
            0.     ,    0.     ,    1.     ,    0.     ]

When I launch I confirm the correct url with

ros2 param dump /front/ImagePublisher

which yields:

ros__parameters:
? ''
: image_raw:
    format: jpeg
    jpeg_quality: 95
    png_level: 3
    tiff:
      res_unit: inch
      xdpi: -1
      ydpi: -1
camera_info_url: file:///Git/isaac/install/marvin_data_collector/share/marvin_data_collector/config/front_camera_info.yaml
filename: rtsp://admin:[email protected]:554/h264
flip_horizontal: false
flip_vertical: false
frame_id: camera
publish_rate: 1.0
qos_overrides:
  /parameter_events:
    publisher:
      depth: 10
      durability: volatile
      history: keep_last
      reliability: best_effort
retry: false
timeout: 2000
use_sim_time: false

But when I confirm by looking at the camera_info being published with

ros2 topic echo /front/camera_info

I get:

header:
  stamp:
    sec: 1717668777
    nanosec: 101004015
  frame_id: camera
height: 1080
width: 1920
distortion_model: plumb_bob
d:
- 0.0
- 0.0
- 0.0
- 0.0
- 0.0
k:
- 1.0
- 0.0
- 960.0
- 0.0
- 1.0
- 540.0
- 0.0
- 0.0
- 1.0
r:
- 1.0
- 0.0
- 0.0
- 0.0
- 1.0
- 0.0
- 0.0
- 0.0
- 1.0
p:
- 1.0
- 0.0
- 960.0
- 0.0
- 0.0
- 1.0
- 540.0
- 0.0
- 0.0
- 0.0
- 1.0
- 0.0
binning_x: 0
binning_y: 0
roi:
  x_offset: 0
  y_offset: 0
  height: 0
  width: 0
  do_rectify: false

Obviously the config gets ignored, I just don't understand why. In a different post it was mentioned that perhaps the config values may be out of bounds. So I also tried with a config file that had minimal changes compared to the camera_info that gets published. But even that didn't work.

Answer 1

It seems this is a bug in the image-publisher Node. The parameter camera_info_url is not loaded correctly.

Solution was to set the parameter after the node was launched.

This can be done at the end of the launchfile doing something like this:

ExecuteProcess(
        cmd=['ros2', 'param', 'set', '/front/ImagePublisher', 'camera_info_url', front_camera_info_url],
        output='screen'
        ),