REVIEW 4 major objections 5 minor 31 references
Efficient Dynamic LiDAR Odometry for Mobile Robots with Structured Point Clouds
T0 review · 4 major / 5 minor · reviewed 2026-08-12 · deepseek-v4-flash
Pith's one-line read This paper claims that the residuals already produced by GICP scan matching can distinguish dynamic from static objects in structured LiDAR clouds, enabling real-time dynamic odometry on a CPU with 14.3 ms added overhead.
desk verdict Solid efficiency contribution with a novel residual-based dynamic detector, but the accuracy claim is overstated and the repeated-traversal failure mode is real; conditional accept. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The central object is the residual image: after the scan-to-submap GICP stage converges, each point in the current scan retains a residual equal to the Euclidean distance to its nearest neighbor in the submap, and these values are projected onto the same cylindrical coordinates as the range image. Because the moving object is absent from the submap, its points should have larger residuals than static points, so averaging the residuals over each range-image segment gives a per-object score $r_{avg}$. The decision rule is the height-scaled threshold $r_{avg} \geq \theta_{res} h_S$, where $h_S$ is the vertical extent of the segment; this rule is applied only after an object has been seen for a minimum number of frames and has moved a minimum displacement. The same machinery also includes range-image segmentation by connected components and Kalman-filter-based tracking with Hungarian assignment, which turn the per-frame classification into stable object identities and allow dynamic points to be removed before the scan is added to the submap.
What would settle it
Measure the segment-average GICP residuals for a moving pedestrian and a static pole of the same height and distance across several scans: the paper's rule requires a clean separation between these distributions, so a large overlap between the two residual distributions would directly refute the residual heuristic's core premise.
Extended reading notes
Core claim
The discovery the paper aims to establish is that dynamic object detection can be obtained almost for free from the scan-matching residuals already computed for odometry. In the scan-to-submap stage of GICP, the current scan is aligned to a submap built from past scans; because a moving object was not part of that submap, its points' nearest-neighbor distances after convergence are systematically larger. Projecting these residuals to the range image and averaging them per segmented object yields a scalar $r_{avg}$ per candidate segment. The paper's rule declares an object dynamic when $r_{avg} \geq \theta_{res} h_S$, where $h_S$ is the segment's vertical extent, after a minimum number of detections and a minimum displacement; such objects are tracked with Kalman filters, removed from the scan before map integration, and their bounding-box histories are used to erase ghost traces from the global map. The paper argues this is enough to match the practical detection capability of a volumetric method on its real-world data while taking a small fraction of its processing time, and to detect highly articulated objects at full point-cloud resolution.
Load-bearing premise
The method assumes that moving objects are consistently absent from the map used for scan matching, so their matching errors remain higher than static points' errors, and that these errors can be separated by a height-scaled threshold; the paper itself notes this fails when objects repeatedly cross the same area and leave residual traces in the map.
Editorial extensions
If this is right
- A robot's odometry module can double as a dynamic-object detector at roughly 14.3 ms of added overhead per scan, making dynamic handling practical on CPUs without GPUs.
- Because classification does not rely on object classes, arbitrary and unknown objects—including rescue workers, animals, or equipment—can be flagged as dynamic whenever their residual signal is high enough.
- Removing dynamic points before the keyframe database is updated reduces ghost-trace artifacts in the map, and the global-map bounding-box rollback removes traces left by objects that started static.
- Object tracks, with IDs and bounding boxes, are outputs available for downstream tasks such as following a person, motion planning, or human-robot interaction.
Reading between the lines
- One extension the paper leaves implicit is that the residual signal could be used as a self-supervised cue: rather than hand-setting the threshold $\theta_{res}$, a robot could collect residual distributions during operation and fit the decision boundary from observed data, which might recover detections in environments where the fixed linear threshold misfires.
- A testable extension is to combine the residual image with short-term occupancy blanking: when an object is classified as dynamic, temporarily remove or downweight the submap points it generated, which may prevent the ghost-trace failure the paper documents for repeated crossings.
- Because the residual image is a byproduct of registration, the same idea might transfer to other registration-based odometry systems or to scan-to-scan residuals, yielding earlier dynamic cues before a submap has accumulated enough static evidence.
- The method's dependence on structured point clouds is a practical boundary; applying the residual-average heuristic to unstructured clouds would require an alternative spatial aggregation, such as voxel or kd-tree grouping, replacing the range-image projection.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes a real-time dynamic LiDAR odometry pipeline for ground robots that extends Direct LiDAR Odometry (DLO) with range-image segmentation, a residual-based heuristic for distinguishing dynamic from static objects, Kalman-filter-based tracking, and removal of dynamic points before map integration. The main novelty is reusing GICP scan-matching residuals, which are already computed by the odometry module, as the basis for dynamic object classification, thereby avoiding learned networks and dense volumetric maps. The authors report an average total processing time of 46.0 ms per scan (14.3 ms overhead for detection and tracking) on a consumer laptop, and they evaluate detection accuracy on the DOALS small town simulation sequence and qualitatively on a newly recorded real-world dataset. They report IoU/precision/recall of 0.48/0.78/0.49 on DOALS versus Dynablox's 0.69/0.99/0.69, while still describing the detection performance as comparable in the abstract.
Significance. If the central claims held, the paper would offer a lightweight, training-free approach to dynamic object detection integrated with LiDAR odometry, which is valuable for computationally constrained rescue robots. The efficiency contribution is credible and well supported by the timing analysis in Section IV-E, and the open-source release of code and a new dataset is a concrete strength. The idea of reusing GICP residuals as a dynamic/static cue is elegant and the authors are transparent about several failure modes. However, the detection accuracy evidence is the weak pillar: the reported quantitative results are substantially below Dynablox on all metrics, the parameters are tuned on the evaluation data without a validation split, and the central residual assumption fails in repeated-traversal scenarios. The paper is a useful engineering contribution, but the headline claim of comparable detection performance requires revision and additional validation.
major comments (4)
- [Abstract; Section IV-C] The claim of 'comparable detection performance' is contradicted by the paper's own quantitative evaluation. On the DOALS small town sequence, the proposed method attains IoU/precision/recall of 0.48/0.78/0.49 versus Dynablox's 0.69/0.99/0.69 (Section IV-C). Every metric is substantially lower, especially precision and recall, so the abstract and introduction should be revised to characterize the detection performance accurately or supplemented with additional evidence supporting the comparison.
- [Section IV-C; Figure 5] The reported detection operating point appears to be selected on the evaluation data itself. The authors state that parameters were 'adjusted ... manually with reasonable effort to achieve optimal results' (Section IV-C), and Figure 5 sweeps theta_res on the same DOALS sequence to illustrate the precision-recall trade-off. Without a separate validation split or cross-validation, the reported IoU/precision/recall may overstate achievable performance. Please provide a validation protocol and report the sensitivity of the results to theta_res, theta_disp, nmin, and nmax.
- [Section III-B2; Section IV-F] The central assumption that moving objects produce higher GICP residuals than static objects is violated in precisely the repeated-traversal cases documented in Section IV-F: ghost traces left in the submap lower the residuals of later objects at the same location, preventing their detection. Since the DOALS quantitative evaluation uses objects on looped trajectories, this failure mechanism directly explains the large gap to Dynablox and limits the method's applicability in USAR environments where areas are commonly re-crossed. This limitation should be elevated to a central scope condition in the abstract and conclusions, not only mentioned in the limitations paragraph.
- [Section IV-D] Tracking performance, which is a stated contribution, is only evaluated qualitatively. The description of two persons being tracked over 480 s with three ID switches is informative, but quantitative tracking metrics (e.g., MOTA, MOTP, ID switch counts, or similar) would be needed to support the claim of 'robust object tracking'. The current evidence is anecdotal and does not permit a comparison with other DATMO approaches.
minor comments (5)
- [Section III-B] The heading 'Segmantation' should be corrected to 'Segmentation'.
- [Equation (1)] The projection formula contains undefined symbols j and k, and the bracketing of the floor terms is confusing; please clarify the intended coordinate mapping.
- [Section III-C2; Equation (6)] The default values of theta_res, theta_disp, nmin, and nmax are not reported in the text. Since these are the key parameters of the proposed method, please list the exact values used in the evaluation for reproducibility.
- [Section IV-B] When describing the DOALS dataset, the authors state that the original layout was changed from column-major to row-major. Please clarify whether this transformation affects the ground-truth annotations or the comparability of the evaluation with other methods.
- [Table I] There are formatting artifacts in Table I such as '31 .7' and '3 .5'; please unify the spacing and units.
Circularity Check
Detection-performance claim rests on thresholds hand-tuned on the evaluation sequence; efficiency claim is independent.
-
fitted input called prediction
[Section IV-C (Evaluation) and Fig. 5, with Eq. (6) in Section III-C.2]
"We have adjusted them manually with reasonable effort to achieve optimal results. ... Fig. 5 shows the trade-off between FP and FN point detections for different residuum thresholds."
Equation (6) classifies a segment as dynamic when ravg >= theta_res * hS, with theta_res described as a 'heuristic threshold.' The quantitative DOALS results in Section IV-C (IoU/precision/recall 0.48/0.78/0.49) are obtained after manually adjusting theta_res and the other parameters 'to achieve optimal results' on the same sequence, and Fig. 5 sweeps theta_res to display the resulting trade-off. Thus the reported 'comparable detection performance' is a selected operating point on the test data, not an independent prediction, and no held-out validation or fixed a-priori threshold is reported. The 14.3 ms runtime overhead is a separately measured quantity and does not inherit this circularity.
full rationale
No load-bearing self-citation chain or definitional equivalence was found. The odometry backbone DLO [5] and the range-image segmentation [28] are external works, and [6] is a requirements citation that is not load-bearing. The only circularity-like step is the manual tuning of theta_res, nmin, nmax, and theta_disp on the evaluation data. Because the central 'comparable detection performance' claim is supported by numbers obtained at a manually optimized operating point, that part of the evaluation is partly a fit rather than a prediction. The paper's own Section IV-F admits that the residual heuristic fails under repeated traversal, which further weakens the general claim but is a limitation rather than a circularity. The efficiency contribution (14.3 ms overhead, 46.0 ms total) and the qualitative tracking results are independent of this threshold fitting.
Assumptions & free parameters
free parameters (5)
- theta_res =
not reported; swept in Fig. 5 over 0 to 0.6
- theta_disp =
not reported
- nmin / nmax =
not reported
- alpha, beta =
not reported
- Segmentation thresholds from Bogoslavskyi et al. =
adopted from prior work
assumptions (5)
- domain assumption Dynamic objects are not represented in the submap, so their scan-matching residuals are higher than static points.
- domain assumption Average residual of an object scales linearly with its height hS, justifying the threshold ravg >= theta_res * hS.
- domain assumption Range image projection and segmentation faithfully map physical objects to segments.
- standard math GICP scan matching converges and residuals are meaningful nearest-neighbor distances.
- domain assumption The robot operates on ground with structured point clouds in row-major layout.
Cite this review
Pith. "Pith review of Efficient Dynamic LiDAR Odometry for Mobile Robots with Structured Point Clouds." pith.science (2026). https://pith.science/paper/NASPXWMP
@misc{pith2026241118443,
author = {Pith},
title = {Pith review of: Efficient Dynamic LiDAR Odometry for Mobile Robots with Structured Point Clouds},
year = {2026},
howpublished = {\url{https://pith.science/paper/NASPXWMP}},
note = {Machine review of arXiv:2411.18443}
}
read the original abstract
We propose a real-time dynamic LiDAR odometry pipeline for mobile robots in Urban Search and Rescue (USAR) scenarios. Existing approaches to dynamic object detection often rely on pretrained learned networks or computationally expensive volumetric maps. To enhance efficiency on computationally limited robots, we reuse data between the odometry and detection module. Utilizing a range image segmentation technique and a novel residual-based heuristic, our method distinguishes dynamic from static objects before integrating them into the point cloud map. The approach demonstrates robust object tracking and improved map accuracy in environments with numerous dynamic objects. Even highly non-rigid objects, such as running humans, are accurately detected at point level without prior downsampling of the point cloud and hence, without loss of information. Evaluation on simulated and real-world data validates its computational efficiency. Compared to a state-of-the-art volumetric method, our approach shows comparable detection performance at a fraction of the processing time, adding only 14 ms to the odometry module for dynamic object detection and tracking. The implementation and a new real-world dataset are available as open-source for further research.
Figures
Figures from the paper (6 more)
Reference graph
Works this paper leans on
-
[1]
H. Lim, S. Hwang, and H. Myung, “ERASOR: Egocentric Ratio of Pseudo Occupancy-based Dynamic Object Removal for Static 3D Point Cloud Map Building,” IEEE Robotics and Automation Letters , pp. 2272–2279, 2021
work page 2021
-
[2]
3dssd: Point-based 3d single stage object detector,
Z. Yang, Y . Sun, S. Liu, and J. Jia, “3dssd: Point-based 3d single stage object detector,” in Proc. IEEE Conf. Comput. Vis. Pattern Recognit. (CVPR), 2020, pp. 11 040–11 048
work page 2020
-
[3]
Pointpillars: Fast encoders for object detection from point clouds,
A. H. Lang, S. V ora, H. Caesar, L. Zhou, J. Yang, and O. Beijbom, “Pointpillars: Fast encoders for object detection from point clouds,” in Proc. IEEE Conf. Comput. Vis. Pattern Recognit. (CVPR) , 2019, pp. 12 697–12 705
work page 2019
-
[4]
Rangenet++: Fast and accurate lidar semantic segmentation,
A. Milioto, I. Vizzo, J. Behley, and C. Stachniss, “Rangenet++: Fast and accurate lidar semantic segmentation,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS) , 2019, pp. 4213–4220
work page 2019
-
[5]
Direct lidar odometry: Fast localization with dense point clouds,
K. Chen, B. T. Lopez, A.-a. Agha-mohammadi, and A. Mehta, “Direct lidar odometry: Fast localization with dense point clouds,” IEEE Robotics and Automation Letters , vol. 7, no. 2, pp. 2000–2007, 2022
2000
-
[6]
K. Daun and O. von Stryk, “Requirements and challenges for auton- omy and assistance functions for ground rescue robots in reconnais- sance missions,” in IEEE Intl. Symposium on Safety, Security, and Rescue Robotics (SSRR) , 2023 in press
work page 2023
-
[7]
Loam: Lidar odometry and mapping in real- time
J. Zhang and S. Singh, “Loam: Lidar odometry and mapping in real- time.” in Robotics: Science and systems , vol. 2, no. 9. Berkeley, CA, 2014, pp. 1–9
2014
-
[8]
Lego-loam: Lightweight and ground- optimized lidar odometry and mapping on variable terrain,
T. Shan and B. Englot, “Lego-loam: Lightweight and ground- optimized lidar odometry and mapping on variable terrain,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS) . IEEE, 2018, pp. 4758–4765
work page 2018
Show all 31 references
-
[9]
Dynablox: Real-time detection of diverse dynamic objects in complex environments,
L. Schmid, O. Andersson, A. Sulser, P. Pfreundschuh, and R. Siegwart, “Dynablox: Real-time detection of diverse dynamic objects in complex environments,” IEEE Robotics and Automation Letters , 2023
2023
-
[10]
Online simultaneous local- ization and mapping with detection and tracking of moving objects: theory and results from a ground vehicle in crowded urban areas,
C.-C. Wang, C. Thorpe, and S. Thrun, “Online simultaneous local- ization and mapping with detection and tracking of moving objects: theory and results from a ground vehicle in crowded urban areas,” in IEEE Intl. Conf. Robot. Automat. , vol. 1, 2003, pp. 842–849
2003
-
[11]
Mapless online detection of dynamic objects in 3d lidar,
D. Yoon, T. Tang, and T. Barfoot, “Mapless online detection of dynamic objects in 3d lidar,” inIEEE Conf. Comp. Robot Vision (CRV), 2019, pp. 113–120
2019
-
[12]
Yolact: Real-time instance segmentation,
D. Bolya, C. Zhou, F. Xiao, and Y . J. Lee, “Yolact: Real-time instance segmentation,” in Proc. IEEE/CVF Intl. Conf. Comput. Vis. (ICCV) , 2019, pp. 9157–9166
2019
-
[13]
Street environment change detection from mobile laser scanning point clouds,
W. Xiao, B. Vallet, M. Br ´edif, and N. Paparoditis, “Street environment change detection from mobile laser scanning point clouds,” ISPRS Journal of Photogrammetry and Remote Sensing , vol. 107, pp. 38–49, 2015
2015
-
[14]
Detection, classification and tracking of moving objects in a 3d environment,
A. Azim and O. Aycard, “Detection, classification and tracking of moving objects in a 3d environment,” in IEEE Intelligent Vehicles Symposium, 2012, pp. 802–807
2012
-
[15]
Robust moving objects detection in lidar data exploiting visual cues,
G. Postica, A. Romanoni, and M. Matteucci, “Robust moving objects detection in lidar data exploiting visual cues,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS) , 2016, pp. 1093–1098
2016
-
[16]
V oxblox: Incremental 3d euclidean signed distance fields for on-board mav planning,
H. Oleynikova, Z. Taylor, M. Fehr, R. Siegwart, and J. Nieto, “V oxblox: Incremental 3d euclidean signed distance fields for on-board mav planning,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS), 2017, pp. 1366–1373
2017
-
[17]
Khronos: A unified approach for spatio-temporal metric-semantic slam in dynamic environments,
L. Schmid, M. Abate, Y . Chang, and L. Carlone, “Khronos: A unified approach for spatio-temporal metric-semantic slam in dynamic environments,” arXiv preprint arXiv:2402.13817 , 2024
2024 arXiv
-
[18]
Motion-based detection and tracking in 3d lidar scans,
A. Dewan, T. Caselitz, G. D. Tipaldi, and W. Burgard, “Motion-based detection and tracking in 3d lidar scans,” in IEEE Intl. Conf. on Robotics and Automation (ICRA) , 2016, pp. 4508–4513
2016
-
[19]
Joint self-localization and tracking of generic objects in 3d range data,
F. Moosmann and C. Stiller, “Joint self-localization and tracking of generic objects in 3d range data,” in IEEE Intl. Conf. on Robotics and Automation (ICRA), 2013, pp. 1146–1152
2013
-
[20]
Rigid scene flow for 3d lidar scans,
A. Dewan, T. Caselitz, G. D. Tipaldi, and W. Burgard, “Rigid scene flow for 3d lidar scans,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS), 2016, pp. 1765–1770
2016
-
[21]
DRR- LIO: A Dynamic-Region-Removal-Based LiDAR Inertial Odometry in Dynamic Environments,
Y . Wang, W. Yao, B. Zhang, J. Fu, J. Yang, and G. Sun, “DRR- LIO: A Dynamic-Region-Removal-Based LiDAR Inertial Odometry in Dynamic Environments,” IEEE Sensors Journal , vol. 23, pp. 13 175– 13 185, 2023
2023
-
[22]
Explicit 3D change detection using ray-tracing in spherical coordinates,
J. P. Underwood, D. Gillsj ¨o, T. Bailey, and V . Vlaskine, “Explicit 3D change detection using ray-tracing in spherical coordinates,” in IEEE Intl. Conf. on Robotics and Automation (ICRA) , 2013, pp. 4735–4741
2013
-
[23]
Dynamic obstacles detection and 3d map updating,
F. Ferri, M. Gianni, M. Menna, and F. Pirri, “Dynamic obstacles detection and 3d map updating,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS) , 2015, pp. 5694–5699
2015
-
[24]
Long- term 3D map maintenance in dynamic environments,
F. Pomerleau, P. Krusi, F. Colas, P. Furgale, and R. Siegwart, “Long- term 3D map maintenance in dynamic environments,” in IEEE Intl. Conf. on Robotics and Automation (ICRA) , 2014, pp. 3712–3719
2014
-
[25]
Multi-session map construction in outdoor dynamic environment,
X. Ding, Y . Wang, H. Yin, L. Tang, and R. Xiong, “Multi-session map construction in outdoor dynamic environment,” in IEEE Intl. Conf. on Real-time Computing and Robotics (RCAR) , 2018, pp. 384–389
2018
-
[26]
The peopleremover—removing dynamic objects from 3-d point cloud data by traversing a voxel occupancy grid,
J. Schauer and A. N ¨uchter, “The peopleremover—removing dynamic objects from 3-d point cloud data by traversing a voxel occupancy grid,” IEEE Robotics and Automation letters , vol. 3, pp. 1679–1686, 2018
2018
-
[27]
Lio-dor: A robust lidar inertial odometry with real-time dynamic object removal,
L. Mao, W. Gao, H. Chen, and S. Zhang, “Lio-dor: A robust lidar inertial odometry with real-time dynamic object removal,” in IEEE Intl. Conf. on Robotics and Biomimetics (ROBIO) , 2023, pp. 1–7
2023
-
[28]
Fast range image-based segmenta- tion of sparse 3D laser scans for online operation,
I. Bogoslavskyi and C. Stachniss, “Fast range image-based segmenta- tion of sparse 3D laser scans for online operation,” in IEEE Intl. Conf. on Intelligent Robots and Systems (IROS) , 2016, pp. 163–169
2016
-
[29]
Ab3dmot: A baseline for 3d multi-object tracking and new evaluation metrics,
X. Weng, J. Wang, D. Held, and K. Kitani, “Ab3dmot: A baseline for 3d multi-object tracking and new evaluation metrics,” arXiv preprint arXiv:2008.08063, 2020
2008 arXiv
-
[30]
The Hungarian method for the assignment problem,
H. W. Kuhn, “The Hungarian method for the assignment problem,” Naval Research Logistics Quarterly , vol. 2, pp. 83–97, 1955
1955
-
[31]
Dynamic Object Aware LiDAR SLAM based on Automatic Generation of Training Data,
P. Pfreundschuh, H. F. C. Hendrikx, V . Reijgwart, R. Dub ˜A©, R. Sieg- wart, and A. Cramariuc, “Dynamic Object Aware LiDAR SLAM based on Automatic Generation of Training Data,” in IEEE Intl. Conf. on Robotics and Automation (ICRA) , 2021, pp. 11 641–11 647
2021
Reviewed August 12, 2026 · model on record in the stance chip above.
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