Organizations: School of Remote Sensing and Geomatics Engineering, Nanjing University of Information Science and Technology, China, Nanjing, 210044, China · Nanjing Center, China Geological Survey, Nanjing, 210016, China · School of Automation, Southeast University, Nanjing, 210096, China
The semantic information of objects in remote sensing images is typically invariant to geometric transformations from the dihedral group D4. However, SAM3-based open-vocabulary semantic segmentation (OVSS) methods often exhibit inconsistent responses to different geometric transformations. To exploit this property and improve the stability of OVSS for remote sensing images, we propose a feature-adaptive manifold repair method based on dihedral-group geometric transformations. First, we introduce multi-scale harmonic-guided D4 view selection (MH-D4VS) to select complementary candidate views from a set of geometrically transformed views. Next, we propose original-view-anchored adaptive manifold repair (OAMR), which uses the original view as an anchor and reliable cross-view information to selectively repair locally unreliable visual features. Finally, we develop pixel decoder test-time adaptation (PD-TTA) for SAM3, which fine-tunes only the parameters of the GroupNorm layers online during inference, thereby enhancing the model's ability to adapt to sample-level distribution shifts. Experimental results show that the proposed method achieves an average mIoU of 55.6% across eight remote sensing semantic segmentation benchmarks and delivers consistent performance improvements under different SAM3-based inference frameworks.
Figures & tables
Figure 1: Overview of the proposed Geometry-Transformation-Aware Feature-Adaptive Manifold Restoration framework (GFMR). GFMR consists of three components including MH-D4VS, OAMR and PD-TTA.
Figure 2: Overview of MH-D4VS. Multi-scale oriented edges are first used to construct and aggregate first- to fourth-order complex harmonic moments, while chirality is computed to capture handedness information. The action of the D4 group is then applied to derive the structural preferences of different geometric views. Finally, the optimal three-view combination C∗ is selected by jointly considering structural quality Q(C) , geometric diversity D(C) , and transformation-family balance F(C) . The selected views are combined with the original view O to form the multi-view representation used in subsequent processing.
Figure 3: Overview of OAMR. Features from the three candidate views are first aligned to the original coordinate system through inverse D4 transformations, and reliable cross-view observations are used to construct adaptive local subspaces. Refined cross-view metrics and candidate support then identify reliable replacement sources, enabling selective repair only of original-view features that deviate significantly from the local manifold. Finally, candidate-source consistency at a high-resolution feature level guides cross-scale extension at the target repair level.
Figure 4: The PD-TTA in PixelDecoder of SAM3
Figure 5: Qualitative comparison of the proposed method with existing open-vocabulary semantic segmentation methods.
Method
OpenEarthMap
LoveDA
iSAID
Potsdam
Vaihingen
UAVid
UDD5
VDD
Avg.
CLIP [ 1 ]
12.0
12.4
7.5
15.6
10.8
10.9
9.5
14.2
11.6
MaskCLIP [ 2 ]
25.1
27.8
14.5
33.9
29.9
28.6
32.4
32.9
28.1
SCLIP [ 3 ]
29.3
30.4
16.1
39.6
35.9
31.4
38.7
37.9
32.4
GEM [ 60 ]
33.9
31.6
17.7
39.1
36.4
33.4
41.2
39.5
34.1
ClearCLIP [ 4 ]
31.0
32.4
18.2
42.0
36.2
36.2
41.8
39.3
34.6
ProxyCLIP [ 11 ]
38.9
34.3
21.8
49.0
47.5
35.8
40.8
47.8
39.5
Table 1: Performance comparison of open-vocabulary semantic segmentation methods on eight remote sensing benchmark datasets (mIoU, %). The best results are highlighted in bold.
Method
OpenEarthMap
LoveDA
iSAID
Potsdam
Vaihingen
UAVid
UDD5
VDD
Avg.
ProC-SAM3
41.0
41.6
20.7
57.1
60.4
54.3
71.6
64.1
51.4
ProC-SAM3 + MH-D4VS + OAMR
47.7
42.0
25.8
57.3
60.6
54.6
72.4
65.4
53.2
Table 2: Evaluation of the proposed training-free visual adaptation modules on ProC-SAM3, another SAM 3-based framework (mIoU, %).
Figure 6: Qualitative results of the proposed method within the ProC-SAM3 framework. (a) Input images; (b) predictions from the original ProC-SAM3; (c) predictions after integrating the proposed MH-D4VS and OAMR modules; (d) ground truth.
Ablation Setting
MH-D4VS
OAMR
PD-TTA
OpenEarthMap
Vaihingen
VDD
A. (SegEarth-OV3 baseline)
–
–
–
42.90
60.80
64.50
B.
✓
×
–
44.16
60.77
53.05
C.
×
✓
–
46.27
62.74
64.79
D.
∘
✓
–
47.21
63.17
65.06
E.
✓
✓
–
48.78
63.79
65.77
F.
✓
✓
✓
49.45
64.30
66.21
Table 3: Overall ablation results for MH-D4VS, OAMR, and PD-TTA (mIoU, %). A dash (–) indicates that the original SegEarth-OV3 baseline configuration is retained without introducing the corresponding module or replacement strategy. A check mark ( ✓ ) indicates the proposed module. For MH-D4VS, a cross ( × ) denotes Random-3 view selection, while a circle ( ∘ ) denotes the use of all candidate views. For OAMR, a cross ( × ) denotes Mean Fusion. PD-TTA denotes Pixel Decoder Test-Time Adaptation.
Figure 7: Qualitative comparison of different ablation configurations. From left to right: representative samples from the OpenEarthMap, Vaihingen, and VDD datasets.
Multi-Scale Harmonic Structural Encoding
Cross-Order Harmonic Chirality Representation
Diversity-Aware Triplet Selection
OpenEarthMap
Vaihingen
VDD
×
✓
✓
48.17
63.56
65.71
✓
×
✓
48.07
63.58
65.62
✓
✓
×
48.19
63.64
65.72
✓
✓
✓
49.45
64.30
66.21
Table 4: Ablation study of different components in MH-D4VS (mIoU, %).
Adaptive Local Subspace Modeling
Refined Cross-View Metric-Guided Refit
Cross-Scale Guidance
OpenEarthMap
Vaihingen
VDD
×
✓
✓
44.13
60.88
64.35
✓
×
✓
44.24
60.90
64.36
✓
✓
×
46.26
63.74
65.64
✓
✓
✓
49.45
64.30
66.21
Table 5: Ablation study of different components in OAMR (mIoU, %).
Figure 8: Visualization of multi-view feature repair with OAMR. On the left, the top row shows the Original View and three transformed views (Principal, Secondary, and Third), while the bottom row visualizes their features in a shared PCA space after alignment to the original coordinate system. The right panel shows the features repaired by OAMR. All features use the same PCA projection and color mapping. Colors indicate only relative feature projections in the low-dimensional PCA space and do not correspond to specific semantic classes.
Figure 9: Spatial distribution, replacement sources, and changes in local manifold consistency for selective feature repair with OAMR. (a) Final feature repair regions, with red locations indicating feature replacement. (b) Distribution of final replacement sources. O indicates retention of the original-view features, while P , S , and T indicate replacement with aligned features from the Principal, Secondary, and Third candidate views, respectively. (c) Spatial distribution of improvements in local manifold anomaly scores. Colors represent the minimum local subspace anomaly score before repair minus the anomaly score after repair. Positive values indicate improved consistency with the local manifold, whereas negative values indicate increased deviation. Black contours delineate the final repair locations, and the displayed values report the mean improvement within the final repair regions. (d) Changes in the feature distribution at the final repair locations in a shared PCA space. Gray crosses denote the means of reliable anchor features. Red and green points represent the original-view features before repair and the candidate features used for replacement, respectively. Connecting lines indicate paired feature changes at the same spatial location, while red and green crosses denote the feature means before and after repair, respectively.
School of Information Science and Technology, Yunnan Normal University, Kunming, China · School of Computer Science and Engineering, Beihang University, Beijing, China · College of Computer Science, Beijing University of Technology, Beijing, China
Faculty of Data Science, City University of Macau, 999078, SAR Macao, China · Chair of Data Science in Earth Observation, Technical University of Munich (TUM), Germany · Munich Center for Machine Learning, Munich, Germany