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 | - | -