Abstract
Autonomous robots operating over long periods must keep their environmental memory up to date as the world changes between visits. In semi-static environments, an object may be replaced in place by a different but geometrically and semantically similar instance, making the identity change difficult to detect from geometry or coarse semantics alone. We present FOCUS, an uncertainty-aware framework for object-level change detection and map maintenance. We formulate semi-static memory maintenance as probabilistic inference that fuses geometric likelihood with appearance likelihood rendered from a 3D Gaussian map. A recursive three-state estimator maintains whether each mapped object is PERSISTED, REPLACED, or REMOVED. To account for imperfect 3DGS rendering, we model the rendered appearance evidence probabilistically rather than using it as a direct change score, with the model parameters automatically calibrated from a change-free replay of the initial mapping session. We evaluate our method on a new Isaac Sim warehouse benchmark with ambiguous in-place replacements and on the real-world TorWIC dataset. It improves object-level replacement F1 from 0.20 to 0.84 over a probabilistic baseline and transfers to real-world data without manual parameter retuning.
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Publication details
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- Open access
- Green open access
Cite this article
APA 7
Xu, C., Yuan, M., Mohammadi, M., & Waslander, S. L. (2026). FOCUS: Fine-Grained Open-Vocabulary Change Detection for Uncertainty-Aware Semi-Static Scenes. https://omanscience.com/en/articles/focus-fine-grained-open-vocabulary-change-detection-for-uncertainty-aware-semi-static-scenes
MLA 9
Xu, Can, et al. "FOCUS: Fine-Grained Open-Vocabulary Change Detection for Uncertainty-Aware Semi-Static Scenes." https://omanscience.com/en/articles/focus-fine-grained-open-vocabulary-change-detection-for-uncertainty-aware-semi-static-scenes.
Chicago (author–date)
Xu, Can, Mingfeng Yuan, Mahan Mohammadi, and Steven L. Waslander. 2026. "FOCUS: Fine-Grained Open-Vocabulary Change Detection for Uncertainty-Aware Semi-Static Scenes." https://omanscience.com/en/articles/focus-fine-grained-open-vocabulary-change-detection-for-uncertainty-aware-semi-static-scenes.
Harvard
Xu, C., Yuan, M., Mohammadi, M. and Waslander, S. L. (2026) 'FOCUS: Fine-Grained Open-Vocabulary Change Detection for Uncertainty-Aware Semi-Static Scenes', Available at: https://omanscience.com/en/articles/focus-fine-grained-open-vocabulary-change-detection-for-uncertainty-aware-semi-static-scenes.
Vancouver
Xu C, Yuan M, Mohammadi M, Waslander SL. FOCUS: Fine-Grained Open-Vocabulary Change Detection for Uncertainty-Aware Semi-Static Scenes. https://omanscience.com/en/articles/focus-fine-grained-open-vocabulary-change-detection-for-uncertainty-aware-semi-static-scenes
IEEE
C. Xu, M. Yuan, M. Mohammadi, and S. L. Waslander, "FOCUS: Fine-Grained Open-Vocabulary Change Detection for Uncertainty-Aware Semi-Static Scenes," https://omanscience.com/en/articles/focus-fine-grained-open-vocabulary-change-detection-for-uncertainty-aware-semi-static-scenes.