marked the performance of both spinning lidar and solid-state
lidar in diverse environments, which limits the development
of more general-purpose lidar-based SLAM algorithms [9]. To
bridge the gap in the literature, we present a benchmark that
compares different modality lidars (spinning, solid-state) in
diverse environments, including indoor offices, long corridors,
halls, forests, and open roads. To allow for more accurate and
fair comparison, we introduce a new method for ground truth
generation in larger indoor spaces (see Fig. 1a). This enhanced
ground truth enables significantly higher degree of quantitative
benchmarking and comparison with respect to our previous
work [9]. We hope for the extended dataset and ground truth
labels, as well as more detailed data, to provide a performance
reference for multi-modal lidar sensors in both structured and
unstructured environments to both academia and industry.
In summary, this work evaluates state-of-the-art SLAM
algorithms with a multi-modal multi-lidar platform as an
extension of our previous work [9]. The main contributions
of this work are as follows:
1) a ground truth trajectory generation method for envi-
ronments where MOCAP or GNSS/RTK are unavailable
that leverages the multi-modality of the data acquisition
platform and high-resolution sensors;
2) a new dataset with data from 5 different lidar sensors,
one lidar camera, and one stereo fisheye cameras in a
variety of environments as illustrated in Fig. 1b. Ground
truth data is provided for all sequences;
3) the benchmarking of ten state-of-the-art filter-based and
optimization-based SLAM methods on our proposed
dataset in terms of the accuracy of odometry, memory and
computing resource consumption. The results indicate the
limitations of current SLAM algorithms and potential
future research directions.
The structure of the paper is as follows. Section II surveys
recent progress in SLAM and existing lidar-based SLAM
benchmarks. Section III provides an overview of the config-
uration of the proposed sensor system. Section IV offers the
detailed benchmark and ground truth generation methodology.
Section V concludes the study and suggests future work.
II. RELATED WORKS
Owing to high accuracy, versatility, and resilience across
environments, 3D lidar SLAM has received much study as a
crucial component of robotic and autonomous systems [10].
In this section, we limit the scope to the well-known and well-
tested 3D lidar SLAM methods. We also include an overview
of the most recent 3D lidar SLAM benchmarks.
A. 3D Lidar SLAM
The primary types of 3D lidar SLAM algorithms to-
day are lidar-only [11], and loosely-coupled [12] or tightly-
coupled [13] with IMU data. Tightly-coupled approaches
integrate the lidar and IMU data at an early stage, in opposition
to SLAM methods that loosely fuse the lidar and IMU outputs
towards the end of their respective processing pipelines.
In terms of lidar-only methods, an early work by Zhang
et al. on Lidar Odometry and Mapping (LOAM) introduced
a method that can achieve low-drift and low-computational
complexity already in 2014 [14]. Since then, there have been
multiple variations of LOAM that enhance its performance. By
incorporating a ground point segmentation and a loop closure
module, LeGO-LOAM is more lightweight with the same
accuracy but improved computational expense and lower long-
term drift [15]. However, lidar-only approaches are mainly
limited by a high susceptibility to featureless landscapes [16],
[17]. By incorporating IMU data into the state estimation
pipeline, SLAM systems naturally become more precise and
flexible.
In LIOM [13], the authors proposed a novel tightly-coupled
approach with lidar-IMU fusion based on graph optimization
which outperformed the state-of-the-art lidar-only and loosely
coupled. Owing to the better performance of tightly-coupled
approaches, subsequent studies have focused in this direction.
Another practical tightly-coupled method is Fast-LIO [18],
which provides computational efficiency and robustness by
fusing the feature points with IMU data through a iter-
ated extended Kalman filter. By extending FAST-LIO, FAST-
LIO2 [19] integrated a dynamic structure ikd-tree to the system
that allows for the incremental map update at every step,
addressing computational scalability issues while inheriting
the tightly-coupled fusion framework from FAST-LIO.
The vast majority of these algorithms function well with
spinning lidars. Nonetheless, new approaches are in demand
since new sensors such as solid-state Livox lidars have
emerged novel sensing modalities, smaller FoVs and irregular
samplings have emerged [9]. Multiple existing studies using
enhanced SLAM algorithms are being researched to fit these
new lidar characteristics. Loam livox [20] is a robust and real-
time LOAM algorithm for these types of lidars. LiLi-OM [6] is
another tightly-coupled method that jointly minimizes the cost
derived from lidar and IMU measurements for both solid-state
Lidars and conventional Lidars.
It is worth mentioning that there are other studies addressing
lidar odometry and mapping by fusing not only IMU but also
visual information or other ranging data for more robust and
accurate state estimation [21], [22].
B. SLAM benchmarks
There are various multi-sensor datasets available online. We
had a systematic comparison of the popular datasets in the
Table III of our former work [9]. Among these datasets, not
all of them have an analytical benchmark of 3D Lidar SLAM
based on multi-modality Lidars. KITTI benchmark [23] is the
most significant one with capabilities of evaluating several
tasks including odometry, SLAM, objects detection, tracking
ans so alike.
III. DATA COLLECTION
Our data collection platform is shown in Fig. 1b, and
details of sensors are listed in Table I. The platform has been
mounted on a mobile wheeled vehicle to adapt to varying
environments. In most scenarios, the platform is manually
pushed or teleoperated, except for the forest environment
where the platform is handheld.