---
license: cc-by-nc-nd-4.0
tags:
- Autonomous Driving
- Computer Vision
---
# Multiagent Multitraversal Multimodal Self-Driving: Open MARS Dataset
[Yiming Li](https://roboticsyimingli.github.io/),
[Zhiheng Li](https://zl3466.github.io/),
[Nuo Chen](),
[Moonjun Gong](https://moonjungong.github.io/),
[Zonglin Lyu](),
[Zehong Wang](),
[Peili Jiang](),
[Chen Feng](https://engineering.nyu.edu/faculty/chen-feng)
[Paper](https://arxiv.org/abs/2406.09383)
[Tutorial](#tutorial)
Checkout our [project website](https://ai4ce.github.io/MARS/) for demo videos.
Codes to reproduce the videos are available in `/visualize` folder of `main` branch.
# Multiagent
# Multitraversal
# News
- [2024/06] Both Multiagent and Multitraversal subsets are now available for download on [huggingface](https://huggingface.co/datasets/ai4ce/MARS).
- [2024/06]The preprint version is available on [arXiv]([https://huggingface.co/datasets/ai4ce/MARS](https://arxiv.org/abs/2406.09383)).
- [2024/02] Our paper has been accepted on CVPR 2024 🎉🎉🎉
# Abstract
In collaboration with the self-driving company [May Mobility](https://maymobility.com/), we present the MARS dataset which unifies scenarios that enable multiagent, multitraversal, and multimodal autonomous vehicle research.
MARS is collected with a fleet of autonomous vehicles driving within a certain geographical area. Each vehicle has its own route and different vehicles may appear at nearby locations. Each vehicle is equipped with a LiDAR and surround-view RGB cameras.
We curate two subsets in MARS: one facilitates collaborative driving with multiple vehicles simultaneously present at the same location, and the other enables memory retrospection through asynchronous traversals of the same location by multiple vehicles. We conduct experiments in place recognition and neural reconstruction. More importantly, MARS introduces new research opportunities and challenges such as multitraversal 3D reconstruction, multiagent perception, and unsupervised object discovery.
#### Our dataset uses the same structure as the [NuScenes](https://www.nuscenes.org/nuscenes) Dataset:
- Multitraversal: each location is saved as one NuScenes object, and each traversal is one scene.
- Multiagent: the whole set is a NuScenes object, and each multiagent encounter is one scene.
# License
[CC BY-NC-SA 4.0](https://creativecommons.org/licenses/by-nc-sa/4.0/)
# Bibtex
```
@InProceedings{Li_2024_CVPR,
author = {Li, Yiming and Li, Zhiheng and Chen, Nuo and Gong, Moonjun and Lyu, Zonglin and Wang, Zehong and Jiang, Peili and Feng, Chen},
title = {Multiagent Multitraversal Multimodal Self-Driving: Open MARS Dataset},
booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)},
month = {June},
year = {2024},
pages = {22041-22051}
}
```
# Tutorial
This tutorial explains how the NuScenes structure works in our dataset, including how you may access a scene and query its samples of sensor data.
- [Devkit Initialization](#initialization)
- [Multitraversal](#load-multitraversal)
- [Multiagent](#load-multiagent)
- [Scene](#scene)
- [Sample](#sample)
- [Sample Data](#sample-data)
- [Sensor Names](#sensor-names)
- [Camera](#camera-data)
- [LiDAR](#lidar-data)
- [IMU](#imu-data)
- [Ego & Sensor Pose](#vehicle-and-sensor-pose)
- [LiDAR-Image projection](#lidar-image-projection)
## Initialization
First, install `nuscenes-devkit` following NuScenes's repo tutorial, [Devkit setup section](https://github.com/nutonomy/nuscenes-devkit?tab=readme-ov-file#devkit-setup). The easiest way is install via pip:
```
pip install nuscenes-devkit
```
Import NuScenes devkit:
```
from nuscenes.nuscenes import NuScenes
```
#### Load Multitraversal
loading data of location 10:
```
# The "version" variable is the name of the folder holding all .json metadata tables.
location = 10
nusc = NuScenes(version='v1.0', dataroot=f'/MARS_multitraversal/{location}', verbose=True)
```
#### Load Multiagent
loading data for the full set:
```
nusc = NuScenes(version='v1.0', dataroot=f'/MARS_multiagent', verbose=True)
```
## Scene
To see all scenes in one set (one location of the Multitraversal set, or the whole Multiagent set):
```
print(nusc.scene)
```
Output:
```
[{'token': '97hitl8ya1335v8zkixvsj3q69tgx801', 'nbr_samples': 611, 'first_sample_token': 'udrq868482482o88p9r2n8b86li7cfxx', 'last_sample_token': '7s5ogk8m9id7apixkqoh3rep0s9113xu', 'name': '2023_10_04_scene_3_maisy', 'intersection': 10, 'err_max': 20068.00981996727},
{'token': 'o858jv3a464383gk9mm8at71ai994d3n', 'nbr_samples': 542, 'first_sample_token': '933ho5988jo3hu848b54749x10gd7u14', 'last_sample_token': 'os54se39x1px2ve12x3r1b87e0d7l1gn', 'name': '2023_10_04_scene_4_maisy', 'intersection': 10, 'err_max': 23959.357933579337},
{'token': 'xv2jkx6m0o3t044bazyz9nwbe5d5i7yy', 'nbr_samples': 702, 'first_sample_token': '8rqb40c919d6n5cd553c3j01v178k28m', 'last_sample_token': 'skr79z433oyi6jljr4nx7ft8c42549nn', 'name': '2023_10_04_scene_6_mike', 'intersection': 10, 'err_max': 27593.048433048432},
{'token': '48e90c7dx401j97391g6549zmljbg0hk', 'nbr_samples': 702, 'first_sample_token': 'ui8631xb2in5la133319c5301wvx1fib', 'last_sample_token': 'xrns1rpma4p00hf39305ckol3p91x59w', 'name': '2023_10_04_scene_9_mike', 'intersection': 10, 'err_max': 24777.237891737892},
...
]
```
The scenes can then be retrieved by indexing:
```
num_of_scenes = len(nusc.scene)
my_scene = nusc.scene[0] # scene at index 0, which is the first scene of this location
print(first_scene)
```
Output:
```
{'token': '97hitl8ya1335v8zkixvsj3q69tgx801',
'nbr_samples': 611,
'first_sample_token': 'udrq868482482o88p9r2n8b86li7cfxx',
'last_sample_token': '7s5ogk8m9id7apixkqoh3rep0s9113xu',
'name': '2023_10_04_scene_3_maisy',
'intersection': 10,
'err_max': 20068.00981996727}
```
- `nbr_samples`: number of samples (frames) of this scene.
- `name`: name of the scene, including its date and name of the vehicle it is from (in this example, the data is from Oct. 4th 2023, vehicle maisy).
- `intersection`: location index.
- `err_max`: maximum time difference (in millisecond) between camera images of a same frame in this scene.
## Sample
Get the first sample (frame) of one scene:
```
first_sample_token = my_scene['first_sample_token'] # get sample token
my_sample = nusc.get('sample', first_sample_token) # get sample metadata
print(my_sample)
```
Output:
```
{'token': 'udrq868482482o88p9r2n8b86li7cfxx',
'timestamp': 1696454482883182,
'prev': '',
'next': 'v15b2l4iaq1x0abxr45jn6bi08j72i01',
'scene_token': '97hitl8ya1335v8zkixvsj3q69tgx801',
'data': {
'CAM_FRONT_CENTER': 'q9e0pgk3wiot983g4ha8178zrnr37m50',
'CAM_FRONT_LEFT': 'c13nf903o913k30rrz33b0jq4f0z7y2d',
'CAM_FRONT_RIGHT': '67ydh75sam2dtk67r8m3bk07ba0lz3ib',
'CAM_BACK_CENTER': '1n09qfm9vw65xpohjqgji2g58459gfuq',
'CAM_SIDE_LEFT': '14up588181925s8bqe3pe44d60316ey0',
'CAM_SIDE_RIGHT': 'x95k7rvhmxkndcj8mc2821c1cs8d46y5',
'LIDAR_FRONT_CENTER': '13y90okaf208cqqy1v54z87cpv88k2qy',
'IMU_TOP': 'to711a9v6yltyvxn5653cth9w2o493z4'
},
'anns': []}
```
- `prev`: token of the previous sample.
- `next`': token of the next sample.
- `data`: dict of data tokens of this sample's sensor data.
- `anns`: empty as we do not have annotation data at this moment.
## Sample Data
### Sensor Names
Our sensor names are different from NuScenes' sensor names. It is important that you use the correct name when querying sensor data. Our sensor names are:
```
['CAM_FRONT_CENTER',
'CAM_FRONT_LEFT',
'CAM_FRONT_RIGHT',
'CAM_BACK_CENTER',
'CAM_SIDE_LEFT',
'CAM_SIDE_RIGHT',
'LIDAR_FRONT_CENTER',
'IMU_TOP']
```
---
### Camera Data
All image data are already undistorted.
To load a piece data, we start with querying its `sample_data` dictionary object from the metadata:
```
sensor = 'CAM_FRONT_CENTER'
sample_data_token = my_sample['data'][sensor]
FC_data = nusc.get('sample_data', sample_data_token)
print(FC_data)
```
Output:
```
{'token': 'q9e0pgk3wiot983g4ha8178zrnr37m50',
'sample_token': 'udrq868482482o88p9r2n8b86li7cfxx',
'ego_pose_token': 'q9e0pgk3wiot983g4ha8178zrnr37m50',
'calibrated_sensor_token': 'r5491t78vlex3qii8gyh3vjp0avkrj47',
'timestamp': 1696454482897062,
'fileformat': 'jpg',
'is_key_frame': True,
'height': 464,
'width': 720,
'filename': 'sweeps/CAM_FRONT_CENTER/1696454482897062.jpg',
'prev': '',
'next': '33r4265w297khyvqe033sl2r6m5iylcr',
'sensor_modality': 'camera',
'channel': 'CAM_FRONT_CENTER'}
```
- `ego_pose_token`: token of vehicle ego pose at the time of this sample.
- `calibrated_sensor_token`: token of sensor calibration information (e.g. distortion coefficient, camera intrinsics, sensor pose & location relative to vehicle, etc.).
- `is_key_frame`: disregard; all images have been marked as key frame in our dataset.
- `height`: image height in pixel
- `width`: image width in pixel
- `filename`: image directory relative to the dataset's root folder
- `prev`: previous data token for this sensor
- `next`: next data token for this sensor
After getting the `sample_data` dictionary, Use NuScenes devkit's `get_sample_data()` function to retrieve the data's absolute path.
Then you may now load the image in any ways you'd like. Here's an example using `cv2`:
```
import cv2
data_path, boxes, camera_intrinsic = nusc.get_sample_data(sample_data_token)
img = cv2.imread(data_path)
cv2.imshow('fc_img', img)
cv2.waitKey()
```
Output:
```
('{$dataset_root}/MARS_multitraversal/10/sweeps/CAM_FRONT_CENTER/1696454482897062.jpg',
[],
array([[661.094568 , 0. , 370.6625195],
[ 0. , 657.7004865, 209.509716 ],
[ 0. , 0. , 1. ]]))
```
---
### LiDAR Data
Impoirt data calss "LidarPointCloud" from NuScenes devkit for convenient lidar pcd loading and manipulation.
The `.bcd.bin` LiDAR data in our dataset has 5 dimensions: [ x || y || z || intensity || ring ].
The 5-dimensional data array is in `pcd.points`. Below is an example of visualizing the pcd with Open3d interactive visualizer.
```
import open3d as o3d
from nuscenes.utils.data_classes import LidarPointCloud
sensor = 'LIDAR_FRONT_CENTER'
sample_data_token = my_sample['data'][sensor]
lidar_data = nusc.get('sample_data', sample_data_token)
data_path, boxes, _ = nusc.get_sample_data(my_sample['data'][sensor])
pcd = LidarPointCloud.from_file(data_path)
print(pcd.points)
pts = pcd.points[:3].T
# open3d visualizer
vis1 = o3d.visualization.Visualizer()
vis1.create_window(
window_name='pcd viewer',
width=256 * 4,
height=256 * 4,
left=480,
top=270)
vis1.get_render_option().background_color = [0, 0, 0]
vis1.get_render_option().point_size = 1
vis1.get_render_option().show_coordinate_frame = True
o3d_pcd = o3d.geometry.PointCloud()
o3d_pcd.points = o3d.utility.Vector3dVector(pts)
vis1.add_geometry(o3d_pcd)
while True:
vis1.update_geometry(o3d_pcd)
vis1.poll_events()
vis1.update_renderer()
time.sleep(0.005)
```
Output:
```
5-d lidar data:
[[ 3.7755847e+00 5.0539265e+00 5.4277039e+00 ... 3.1050100e+00
3.4012783e+00 3.7089713e+00]
[-6.3800979e+00 -7.9569578e+00 -7.9752398e+00 ... -7.9960880e+00
-7.9981585e+00 -8.0107889e+00]
[-1.5409404e+00 -3.2752687e-01 5.7313687e-01 ... 5.5921113e-01
-7.5427920e-01 6.6252775e-02]
[ 9.0000000e+00 1.6000000e+01 1.4000000e+01 ... 1.1000000e+01
1.8000000e+01 1.6000000e+01]
[ 4.0000000e+00 5.3000000e+01 1.0200000e+02 ... 1.0500000e+02
2.6000000e+01 7.5000000e+01]]
```
---
### IMU Data
IMU data in our dataset is saved as json files.
```
sensor = 'IMU_TOP'
sample_data_token = my_sample['data'][sensor]
lidar_data = nusc.get('sample_data', sample_data_token)
data_path, boxes, _ = nusc.get_sample_data(my_sample['data'][sensor])
imu_data = json.load(open(data_path))
print(imu_data)
```
Output:
```
{'utime': 1696454482879084,
'lat': 42.28098291158676,
'lon': -83.74725341796875,
'elev': 259.40500593185425,
'vel': [0.19750464521348476, -4.99952995654127e-27, -0.00017731071625348704],
'avel': [-0.0007668623868539726, -0.0006575787383553688, 0.0007131154834496556],
'acc': [-0.28270150907337666, -0.03748669268679805, 9.785771369934082]}
```
- `lat`: GPS latitude.
- `lon`: GPS longitude.
- `elev`: GPS elevation.
- `vel`: vehicle instant velocity [x, y, z] in m/s.
- `avel`: vehicle instant angular velocity [x, y, z] in rad/s.
- `acc`: vehicle instant acceleration [x, y, z] in m/s^2.
---
### Vehicle and Sensor Pose
Poses are represented as one rotation matrix and one translation matrix.
- rotation: quaternion [w, x, y, z]
- translation: [x, y, z] in meters
Sensor-to-vehicle poses may differ for different vehicles. But for each vehicle, its sensor poses should remain unchanged across all scenes & samples.
Vehicle ego pose can be quaried from sensor data. It should be the same for all sensors in the same sample.
```
# get the vehicle ego pose at the time of this FC_data
vehicle_pose_fc = nusc.get('ego_pose', FC_data['ego_pose_token'])
print("vehicle pose: \n", vehicle_pose_fc, "\n")
# get the vehicle ego pose at the time of this lidar_data, should be the same as that queried from FC_data as they are from the same sample.
vehicle_pose = nusc.get('ego_pose', lidar_data['ego_pose_token'])
print("vehicle pose: \n", vehicle_pose, "\n")
# get camera pose relative to vehicle at the time of this sample
fc_pose = nusc.get('calibrated_sensor', FC_data['calibrated_sensor_token'])
print("CAM_FRONT_CENTER pose: \n", fc_pose, "\n")
# get lidar pose relative to vehicle at the time of this sample
lidar_pose = nusc.get('calibrated_sensor', lidar_data['calibrated_sensor_token'])
print("CAM_FRONT_CENTER pose: \n", lidar_pose)
```
Output:
```
vehicle pose:
{'token': 'q9e0pgk3wiot983g4ha8178zrnr37m50',
'timestamp': 1696454482883182,
'rotation': [-0.7174290249840286, 0.0, -0.0, -0.6966316057361065],
'translation': [-146.83352790433003, -21.327001411798392, 0.0]}
vehicle pose:
{'token': '13y90okaf208cqqy1v54z87cpv88k2qy',
'timestamp': 1696454482883182,
'rotation': [-0.7174290249840286, 0.0, -0.0, -0.6966316057361065],
'translation': [-146.83352790433003, -21.327001411798392, 0.0]}
CAM_FRONT_CENTER pose:
{'token': 'r5491t78vlex3qii8gyh3vjp0avkrj47',
'sensor_token': '1gk062vf442xsn86xo152qw92596k8b9',
'translation': [2.24715, 0.0, 1.4725],
'rotation': [0.49834929780875276, -0.4844970241435727, 0.5050790448056688, -0.5116695901338464],
'camera_intrinsic': [[661.094568, 0.0, 370.6625195], [0.0, 657.7004865, 209.509716], [0.0, 0.0, 1.0]],
'distortion_coefficient': [0.122235, -1.055498, 2.795589, -2.639154]}
CAM_FRONT_CENTER pose:
{'token': '6f367iy1b5c97e8gu614n63jg1f5os19',
'sensor_token': 'myfmnd47g91ijn0a7481eymfk253iwy9',
'translation': [2.12778, 0.0, 1.57],
'rotation': [0.9997984797097376, 0.009068089160690487, 0.006271772522201215, -0.016776012592418482]}
```
## LiDAR-Image projection
- Use NuScenes devkit's `render_pointcloud_in_image()` method.
- The first variable is a sample token.
- Use `camera_channel` to specify the camera name you'd like to project the poiint cloud onto.
```
nusc.render_pointcloud_in_image(my_sample['token'],
pointsensor_channel='LIDAR_FRONT_CENTER',
camera_channel='CAM_FRONT_CENTER',
render_intensity=False,
show_lidarseg=False)
```
Output:
