Header stamp: When is/should this be from?
Many messages in ROS include the header, which includes the timestamp.
What is best/expected practice for this? Should the stamp be the time at which the message is sent or the time of the event it is describing.
In particular most nav_msgs and sensor_msgs have headers. It would be my assumption that nav_msgs/odom would be stamped with the instant at which data were taken from the wheel encoders. Likewise, sensor_msgs/LaserScan would be stamped with some time consistently offset with the start of the rev of the scanner. This would then allow odometry and sensor data to be accurately fused.
Is this the case?