CSV Dataset Format

It is often useful to interface the visual-inertial maps with other research tools (such as Python scripts, Matlab, deep learning frameworks). A consistent map constructed from multiple recordings and spanning a large area and a timeframe is very valuable for lifelong mapping, place recognition and other experiments. Maplab contains a CSV exporter that outputs the data stored in the map to a an easily readable format that can be universally accessed.

This page describes the output of csv_export command in the maplab console. The command operates per mission and creates a folder named after the mission id in the export path. For each mission, the following data is exported:

Vertices

File name: vertices.csv

Column	Description	Unit	Frame
1	vertex index	-	-
2	timestamp	ns	-
3	position x	m	global
4	position y	m	global
5	position z	m	global
6	orientation quaternion x	-	global
7	orientation quaternion y	-	global
8	orientation quaternion z	-	global
9	orientation quaternion w	-	global
10	velocity x	m/s	mission
11	velocity y	m/s	mission
12	velocity z	m/s	mission
13	accelerometer bias x	m/s^2	imu/sensor
14	accelerometer bias y	m/s^2	imu/sensor
15	accelerometer bias z	m/s^2	imu/sensor
16	gyroscope bias x	rad/s	imu/sensor
17	gyroscope bias y	rad/s	imu/sensor
18	gyroscope bias z	rad/s	imu/sensor

IMU data

File name: imu.csv

Column	Description	Unit	Frame
1	IMU timestamp	ns	-
2-7	IMU data 1 (6 values)	rad/s and m/s^2	imu/sensor

Tracks/keypoints

File name: tracks.csv

Column	Description	Unit	Frame
1	timestamp	ns	-
2	vertex index	-	-
3	frame index	-	-
4	keypoint index	-	-
5	keypoint measurement 0	px	distorted img
6	keypoint measurement 1	px	distorted img
7	keypoint measurement uncertainty	-	-
8	keypoint scale	-	-
9	keypoint track id	-	-

Descriptors

File name: descriptors.csv

Column	Description	Unit	Frame
1-N	descriptor byte as integer	-	-

The rows are ordered the same as in the tracks file.

Landmarks

File name: landmarks.csv

Column	Description	Unit	Frame
1	landmark index	-	-
2	landmark position x	m	global
3	landmark position y	m	global
4	landmark position z	m	global

Observations

File name: observations.csv

Column	Description	Unit	Frame
1	vertex index	-	-
2	frame index	-	-
3	keypoint index	-	-
4	landmark index	-	-