berndpfrommer/event_array_msgs

ROS1 and ROS2 messages for event based image sensors

ROS package with array 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. They can be decoded with the help of the event_array_codecs package, visualized with the event_array_viewer and converted to other message formats using event_array_tools.

Use the event_array_py package for convenient and fast loading of events in python.

Encoding schemes

• evt3: raw Metavision evt3 data as it comes from the SDK. For decoding refer to Prophesee Metavision documents.

  The content of the time_base field is undefined. Recovery of sensor time requires decoding the data packets.

• mono (deprecated): messages from monochrome cameras such as the DVS and Prophesee Metavision cameras with ON and OFF events on 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.

For encoding and decoding look at the sources in event_array_codecs and event_array_tools.

License

This package is released under the Apache-2 license.