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.

Any contribution that you make to this repository will be under the Apache 2 License, as dictated by that license:

5. Submission of Contributions. Unless You explicitly state otherwise,
   any Contribution intentionally submitted for inclusion in the Work
   by You to the Licensor shall be under the terms and conditions of
   this License, without any additional terms or conditions.
   Notwithstanding the above, nothing herein shall supersede or modify
   the terms of any separate license agreement you may have executed
   with Licensor regarding such Contributions.

Contributors must sign-off each commit by adding a Signed-off-by: ... line to commit messages to certify that they have the right to submit the code they are contributing to the project according to the Developer Certificate of Origin (DCO).