Tracklet Output Specification

This is a main message which includes all the output results during runtime of AkiraKan fusion box. This message will be sent out for each received LiDAR data frame (10Hz).

Communication Specification

Item	Description
Communication Protocol	TCP (ZeroMQ SUB CONNECT)
Data Encoding	FlatBuffers v2.0.0
Output Port	8050

TrackletsPacket

Field	Unit	Data type	Description
frame_id	-	uint16	ID / index of the LiDAR frame / scan. It is incremented every time the sensor completes a rotation, crossing the zero azimuth angle.
count	-	uint16	Object count in the current frame.
lidarts_ms	ms	float64	Timestamp from Ouster LiDAR Time Source. If not synchronize to PTP time source: monotonically increasing counter that will begin counting milliseconds since startup. If synchronize to PTP time source: As soon as a PTP sync event happens, the time will be updated to unix timestamp (milliseconds since 1970). The counter must always count forward in time. If another PTP sync event happens the counter will either jump forward to match the new time, or slow itself down.
unixts_ms	ms	float64	Unix timestamp (milliseconds since 1970) from AkiraKan fusion box
tracklets	-	[Tracklet]	Vector of tracklets in the current frame

Tracklet

Field	Unit	Data type	Description
track_id	-	uint64	The ID of the object being tracked
class_id	-	ClassType (uint8)	Classification of the object
confidence	-	float32	Probability of the confidence of classification result. Values: [0, 1]
bbox	-	BoundingBox	Bounding box of the object
zone_ids	-	[uint16]	Vector of zones occupied by the object

ClassType

Class	Enumeration	Data type
LargeVehicle	0	uint8
SmallVehicle	1	uint8
Cyclist	2	uint8
Pedestrian	3	uint8

BoundingBox

Field	Unit	Data type	Note
position	meters	Vector3 (float32)	XYZ position of the bounding box in the World Coordinate Frame
velocity	m/s	Vector3 (float32)	XYZ velocity of the object
dimension	meters	Vector3 (float32)	x: Longitudinal y: Lateral z: Height
yaw	radians	float32	Bounding box rotation angle along the Z-axis from the positive X-axis

The World Coordinate Frame follows the Right Hand Rule convention. The ground plane aligns along the X-Y plane and Z being altitude.

Vector3

Field	Unit	Data type
x	meters	float32
y	meters	float32
z	meters	float32