All-St3R SLAM: Real-time RGB Dynamic SLAM with Pixel-wise Motion Masking
Authors: Yewon Kim, Paul Hongsuck Seo, Sang Chul Ahn
Organizations: Center for Artificial Intelligence Research, Korea Institute of Science and Technology, Seoul, Korea (South) · Dept. of Computer Science and Engineering, Korea University, Seoul, Korea (South) · Center for Artificial Intelligence Research, Korea Institute of Science and Technology, and with AI-Robotics, KIST School (UST), Seoul, Korea (South)
SLAM (Simultaneous Localization and Mapping) is a core technology in autonomous systems that enables them to estimate their own position and build a map of unknown environments simultaneously. SLAM systems in dynamic environments are of great practical importance. However, existing dynamic SLAM approaches still have several limitations like over-removal and high computational costs. To address these limitations, we propose a real-time RGB Dynamic SLAM framework that precisely removes moving objects at the pixel level without relying on predefined labels or segmentation models. Our system combines pixel motion predicted by ego-motion using DUSt3R with point tracking from All-Tracker, removing only actually moving pixels by analyzing discrepancies between the two motion sources. Unlike object-level masking methods, our approach eliminates only currently moving regions, allowing temporarily static parts to be utilized for tracking. Operating at approximately 10 FPS, the system achieves real-time performance on standard 30 FPS video streams by subsampling every 3 frames. Relying solely on RGB inputs, this significantly improves upon state-of-the-art dense dynamic SLAM approaches (0.5-3 FPS), presenting a highly practical solution.
Figures & tables
Fig. 1: Comparison between Ego-Motion , Point Tracking , and Dynamic Movement . Assuming the KeyFrame point cloud reconstructed by DUSt3R is static, projecting those 3D points into the Frame camera produces the pixel motion predicted by camera Ego-Motion . In contrast, All-Tracker predicts pixel correspondences directly between the KeyFrame and the Frame in the image domain, producing Point Tracking . When the KeyFrame point cloud contains dynamic objects, discrepancies arise between these two motions. Points with large discrepancies between the two motions are regarded as Dynamic Movement .
Fig. 2: Overview of the proposed Monocular RGB Dynamic SLAM system.
Fig. 3: Illustration of the frame-by-frame mask accumulation.
Fig. 4: Object-Level Masking on Bonn Dataset (SAM2). Visualization of dynamic masks generated by SAM2 [ 16 ] on the crowd sequence of the Bonn RGB-D Dataset. Even when motion is limited to a specific part (e.g., moving arms), the entire human body is masked out. This over-removal discards valid static regions such as the torso, significantly reducing the number of valid matching correspondences required for stable tracking.
Fig. 5: Tracking Failure with Object-Level Masking. The visualization shows the system status using SAM2 masks.
Fig. 7: Geometric Verification under Dynamic Occlusion. (Left: Keyframe, Right: Current Frame). Visualization of valid matches (dots) and epipolar lines. Despite large dynamic obstructions, the system maintains accurate epipolar constraints and secures a sufficient number of reliable matches, confirming stable pose estimation.
Dataset
WildGS (Full) [ 8 ]
WildGS (Fast) [ 8 ]
Ours
FPS ↑
ATE ↓
FPS ↑
ATE ↓
FPS ↑
ATE ↓
Wild-SLAM
0.49
0.46
1.96
0.48
11.24
2.17
Bonn
0.50
2.31
2.13
2.47
10.13
2.46
TABLE I: Runtime (FPS ↑ ) and ATE RMSE (cm ↓ ).
Method
Balloon
Balloon2
Crowd
Crowd2
Person
Person2
Moving
Moving2
Avg.
DSO [ 17 ]
7.3
21.8
10.1
7.6
30.6
26.5
4.7
11.2
15.0
DROID-SLAM [ 18 ]
7.5
4.1
5.2
6.5
4.3
5.4
2.3
4.0
4.91
MonoGS [ 19 ]
15.3
17.3
11.3
7.3
26.4
35.2
22.2
47.2
22.8
Splat-SLAM [ 20 ]
8.8
3.0
6.8
F
4.9
25.8
1.7
3.0
-
DynaMoN (MS) [ 21 ]
6.8
3.8
6.1
5.6
2.4
3.5
1.4
2.6
4.02
DynaMoN (MS&SS) [ 21 ]
2.8
2.7
3.5
2.8
14.8
2.2
1.3
2.7
4.10
TABLE II: Tracking Performance and Ablation Study on Bonn RGB-D Dynamic Dataset (ATE RMSE [cm]). Best results are highlighted as first , second , and third . ‘F’ indicates tracking failure.
Method
f2/dp
f3/ss
f3/sx
f3/sr
f3/shs
f3/ws
f3/wr
f3/wx
f3/whs
Avg.
DSO [ 17 ]
2.2
1.7
11.5
3.7
12.4
1.5
12.9
13.8
40.7
11.1
DROID-SLAM [ 18 ]
0.6
0.5
0.9
2.2
1.4
1.2
1.6
4.0
2.2
1.62
MonoGS [ 19 ]
112.8
1.2
6.1
5.1
28.3
1.1
21.5
17.4
44.2
26.4
Splat-SLAM [ 20 ]
0.7
0.5
0.9
2.3
1.5
2.3
1.3
3.9
2.2
1.71
DynaMoN (MS) [ 21 ]
0.6
0.5
0.9
2.1
1.9
1.4
1.4
3.9
2.0
1.63
DynaMoN (MS&SS) [ 21 ]
0.7
0.5
0.9
2.4
2.3
0.7
1.4
3.9
1.9
1.63
TABLE III: Tracking Performance and Ablation Study on TUM RGB-D Dynamic Dataset (ATE RMSE [cm]). Best results are highlighted as first , second , and third . Results are marked with ’-’ when the released implementation could not be successfully reproduced.
Fig. 8: Qualitative comparison on a Static Scene. Reconstruction results on freiburg1_room . Even without the heavy matching head of MASt3R [ 25 ] , our method (combining DUSt3R [ 9 ] with All-Tracker [ 10 ] ) exhibits superior geometric alignment in the reconstructed map. This confirms that our lightweight flow integration effectively compensates for the absence of learned matching features.
Fig. 9: Mask Quality Comparison. Middle: Uncertainty map from WildGS-SLAM [ 8 ] , which is blurry due to feature downsampling. Right: Our pixel-wise dynamic mask on the Bonn dataset, showing high-resolution sharpness and better boundary adherence.
Fig. 10: KeyFrame Dynamic Masks. Visualization of dynamic masks on keyframes from freiburg3_walking_xyz . The system effectively identifies the moving person.
Fig. 11: Reconstruction on Bonn Dataset. Left: Final reconstruction of person_tracking . The moving person is completely removed, resulting in clean geometry. Right: Live tracking visualization showing the current frame (rainbow) aligned to the canonical map, with the dynamic person effectively masked out.
Fig. 12: Generalization: Quadruped Robot. Top: Clean reconstruction. Bottom: Dynamic mask. Our method successfully detects and removes the ANYmal robot without prior knowledge of the object class.
Robust visual Simultaneous Localization and Mapping (vSLAM) in dynamic environments faces challenges due to the presence of moving objects that may introduce erroneous observations, corrupt the map reconstruction and overall degrade localization accuracy. Existing vSLAM approaches often rely on predefined semantic classes or costly pixel-wise classification, limiting their robustness or applicability in real-world scenarios. This paper presents CAOS-SLAM, a dynamic vSLAM framework that extends ORB-SLAM3 with a hybrid perception pipeline to detect, track, and filter both semantically known and previously unseen moving objects in real-time. On-demand panoptic segmentation is performed for object discovery, with candidate unknown objects instantiated through depth-based clustering of unclassified regions. Between panoptic updates, persistent object tracks are updated using lightweight detection when available or temporal mask propagation based on world-frame Kalman prediction, depth consistency, and appearance similarity. The estimated object motion is then used to reject dynamic features from the SLAM pipeline. Experimental results on multiple dynamic RGB-D datasets and real-world experiments demonstrate improved localization accuracy over state-of-the-art dynamic vSLAM approaches, achieving up to 59% lower localization error in scenes characterized by unknown dynamic objects and up to 88% lower error in heavily occluded scenes, while achieving a median processing rate of 30 FPS on a laptop. Furthermore, the tracking module provides estimates of object trajectories and velocities, supporting potential future applications in perception, navigation, and motion-planning tasks in dynamic environments. Code and dataset will be released upon acceptance.
Gaia Borghi, João Carlos Virgolino Soares, Angelo Bratta +2
Dynamic Legged Systems Lab (DLS), Istituto Italiano di Tecnologia, Genoa, Italy · Section of Automation & Control, Department of Electronic Systems, Aalborg University, Denmark
Many existing visual SLAM methods can achieve high localization accuracy in dynamic environments by leveraging deep learning to mask moving objects. However, these methods incur significant computational overhead as the camera tracking needs to wait for the deep neural network to generate mask at each frame, and they typically require GPUs for real-time operation, which restricts their practicality in real-world robotic applications. Therefore, this paper proposes a real-time dynamic SLAM system that runs exclusively on a CPU. Our approach incorporates a mask propagation mechanism that decouples camera tracking and deep learning-based masking for each frame. We also introduce a hybrid tracking strategy that integrates ORB features with optical flow methods, enhancing both robustness and efficiency by selectively allocating computational resources to input frames. Compared to previous methods, our system maintains high localization accuracy in dynamic environments while achieving a tracking frame rate of 60 FPS on a laptop CPU. These results demonstrate the feasibility of utilizing deep learning for dynamic SLAM without GPU support. Since most existing dynamic SLAM systems are not open-source, we make our code publicly available at: https://github.com/yuhaozhang7/NGD-SLAM
Yuhao Zhang, Mihai Bujanca, Mikel Luján
University of Manchester. 2University of Cambridge. · 3Qualcomm Technologies XR Labs, Austria.
We present a robust, real-time RGB SLAM system that handles dynamic environments by leveraging differentiable Uncertainty-aware Bundle Adjustment. Traditional SLAM methods typically assume static scenes, leading to tracking failures in the presence of motion. Recent dynamic SLAM approaches attempt to address this challenge using predefined dynamic priors or uncertainty-aware mapping, but they remain limited when confronted with unknown dynamic objects or highly cluttered scenes where geometric mapping becomes unreliable. In contrast, our method estimates per-pixel uncertainty by exploiting multi-view visual feature inconsistency, enabling robust tracking and reconstruction even in real-world environments. The proposed system achieves state-of-the-art camera poses and scene geometry in cluttered dynamic scenarios while running in real time at around 10 FPS. Code and datasets are available at https://github.com/MoyangLi00/DROID-W.git.