Feat/axis metadata

[andreacalm]

This pull request adds support for detection metadata streaming from Axis cameras in the axis_ptz_node.py node. The main addition is the ability to connect to the camera's analytics metadata endpoint over WebSocket, process bounding-box detections for humans and vehicles, and publish them as ROS messages. The detection stream is configurable and is only enabled if supported by the camera.

Detection metadata integration:

• Added detection metadata streaming to axis_ptz_node.py, allowing the node to connect to Axis analytics scene metadata over WebSocket and publish bounding-box detections for humans and vehicles as robotnik_msgs/AxisMetadataDetectionArray on the ~detectors/status topic. The detection publisher is created only after the camera confirms metadata stream configuration. [1] [2]
• Introduced detection-related parameters (e.g., detection_enabled, detection_use_tls, detection_ws_source, detection_channel_filter) with defaults, and updated the node's initialization and launch argument handling to support these. [1] [2]
• Implemented robust handling for cameras that do not support the metadata endpoint (HTTP 404): detection is disabled and the topic is not advertised in such cases.

Documentation updates:

• Updated README.md to document the new detection metadata feature, including configuration parameters, published topics, and runtime behavior.

Dependency and import changes:

• Added conditional import for the websocket library and necessary ROS message types for detection. [1] [2]

Summary

Topic for viewing camera detections (human/vehicle).

What’s included

• Detection messages/services moved to robotnik_msgs:
  • AxisMetadataDetection.msg
  • AxisMetadataDetectionArray.msg
• Detection documentation updates in README.

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How to Test

rostopic echo /axis_camera_ptz/detectors/status