ROS package with messages for event based cameras

This package has definitions for ROS / ROS2 messages created by event based vision sensors. The events are kept in a compact binary format to avoid slow serialization and deserialization during recording.

Event camera messages can be visualized with the event_camera_renderer and converted to other message formats using event_camera_tools.

For encoding and decoding of messages in C++ look at event_camera_codecs. The event_camera_py package provides a module for fast and convenient loading of events in python.

Messages

EventPacket

The EventPacket message contains a packet (array) of events in binary format. Several different encoding formats are supported, but use of the older, deprecated ones is strongly discouraged.

Description of the encodings:

• evt3: raw Metavision evt3 data as it comes from the SDK. For the details of the encoding scheme refer to the Prophesee Metavision documents.

  The time_base field is not used and its content is undefined. Recovery of sensor time requires decoding the data packets. For more about time stamps see documentation in event_camera_codecs.

• mono (deprecated): messages from monochrome cameras such as the DVS and Prophesee Metavision cameras. Encodes on 64 bit boundaries as follows:

  bits	interpretation
  63	polarity: ON event = 1, OFF event = 0
  48-62	y (15 bits)
  32-48	x (16 bits)
  0-32	dt (32 bits)

  To recover the original sensor time, add the delta dt to the message time_base field. To recover the best estimate ROS sensor time stamp add dt to the header stamp.

• trigger (deprecated): external trigger messages from e.g. the Prophesee Metavision cameras.

  bits	interpretation
  63	polarity: ON event = 1, OFF event = 0
  33-62	unused (31 bits)
  0-32	dt (32 bits)

  To recover the original sensor time add the delta dt to the message time_base field. To recover the best estimate ROS sensor time stamp add dt to the header stamp.

License

This package is released under the Apache-2 license.

Changelog for package event_camera_msgs

1.0.5 (2023-11-09)

• remove linter tests (bombout on galactic)
• Contributors: Bernd Pfrommer

1.0.4 (2023-08-03 11:56)

• updated changelog
• fix cmake bug preventing bombout when ROS_VERSION was not set
• Contributors: Bernd Pfrommer

1.0.3 (2023-08-03 09:41)

• updated changelog
• add dependency on rosidl_default_generators and runtime
• added dependency on ros_environment
• Contributors: Bernd Pfrommer

1.0.2 (2023-07-29 08:07)

• added changelog file
• Contributors: Bernd Pfrommer

1.0.1 (2023-07-29 07:54)

• bumped package version to match tag version
• Contributors: Bernd Pfrommer

1.0.0 (2023-07-13)

• renamed package to event_camera_msgs, msg to EventPacket
• initial commit
• Contributors: Bernd Pfrommer