synchronization
lidar camera synchronization
Note-Currently implemented and tested using a recorded rosbag file,with lidar and camera both running at 10Hz for 10 minutes.
Method in brief-
Initially the bag file is freely running,with the lidar and camera topics being published.The sync event is then published(after 1-2 secs wrt the bag file start time),with the timestamp as the message.The timestamp is the system time.Once the cam_gen.py and lidar_gen.py scripts subscribe(detect) to this sync event,the offset is computed as the difference between the sensors' header timestamp and the timestamp published on the sync event.This offset is then added to the sensors' timestamp to get the corrected timestamp and the data from the two sensors is stored in a folder with the names as the corrected timestamp.
Observation-
Some data is discarded because the corrected timestamps of the lidar camera pair,is not same or has a difference of close to 100ms.
The offset computed is not constant for the entire data,(has a 100ms variation),and hence the offset is computed everytime.
The data stored from the above method is comprised of lidar and image frames having the exact same timestamp.Example of data stored from this sync method is put in the example folder.