rpg_dvs_ros timestamp correct

[KaHo Wong]

Now I am using rpg dvs ros to DAVplorer for ROS development and have a few questions to ask:
1. Is the timestamp assigned to DAVplorer in rpg dvs ros the timestamp of the camera trigger or the timestamp of the camera image?

2. Use ROS timestamp to drive DAVplorer. Is the source of the timestamp ros::time::now() of PC? If yes, won't USB transfer cause a large delay?

[Tobi Delbruck (INI)]

I don't know what you mean by "camera trigger", do you mean DVS event
timestamp? These DVS ON/OFF event timestamps are definitely written to
the rosbags.

I also don't know what you mean by "Use ROS timestamp to drive
DAVplorer." (BTW, it's DVExplorer, not DAVExplorer). The DVS is the
master; it makes the timestamps. It's not like a frame camera that you
trigger to take pictures.

[Luca Longinotti]

The camera timestamps its data and provides its own relative timestamp (relative to start of capture/reset on the camera).

The RPG ROS driver then adds an offset corresponding to ros::Time::now() to make the data relative to the ROS time-source.

Yes, it is possible that any initial delay due to USB when that offset is recorded will then skew further results, but it is currently the best approach without some kind of continuous time synchronization being implemented.

-- 

Luca Longinotti (llongi)

Head of Embedded Platforms
iniVation AG - https://inivation.com/
Zurich, Switzerland
Office: +41 44 500 32 14