Authors: Nafisa Anjum, Satavisa Dey Borno, Ananna Saha, Mir Faiyaz Hossain, Sifat Momen, Nabeel Mohammed, Shafin Rahman
Organizations: North South University, Dhaka, Bangladesh · Department of Electrical and Computer Engineering, North South University, Dhaka, Bangladesh
Hyperspectral image (HSI) classification plays a vital role in remote sensing applications, including agriculture, environmental monitoring, and urban analysis. However, its performance remains challenged by high spectral redundancy, noise sensitivity, and the difficulty of jointly modeling local material composition and long-range spectral dependencies. To address this, we propose AGSA-Net, an abundance-guided self-attention network that explicitly integrates spectral unmixing priors into the classification process. AGSA Net first estimates physically meaningful subpixel abundance maps subject to non-negativity and sum-to-one constraints, regularized by hybrid linear-nonlinear reconstruction decoder. The learned abundances are then used to construct an abundance affinity prior that guides a spectral transformer to emphasize class-discriminative interactions, and the resulting transformer features are fused with compact abundance descriptors for final prediction; in contrast to existing approaches that use abundance as auxiliary or concatenated features. Experiments on Indian Pines, Augsburg, and Berlin demonstrate the benefit of incorporating abundance- guided contextual modeling, particularly in heterogeneous urban scenes. The source code and trained models are available at: https://github.com/nnuvi/AGSA-Net
Figures & tables
Fig. 1: Overview of the proposed AGSA-Net for HSI classification. The framework comprises an unmixing branch and a transformer branch. (a) In contrast to prior approaches that treat abundance maps only as auxiliary inputs or concatenated features, (b) AGSA-Net converts the estimated abundances into a pixel-wise material affinity matrix and injects it directly into the multi-head self-attention as an additive bias, thereby explicitly governing attention formation. This design enforces contextual interactions driven by sub-pixel material composition rather than spectral similarity alone. Final predictions are obtained by fusing abundance-aware transformer features with compact abundance representations.
Fig. 2: Proposed AGSA-Net architecture. Given an input patch Pi,j∈Rp×p×C , the encoder in the first branch estimates pixel-wise abundances vi,j∈RK×p×p , which are flattened and normalized to compute the abundance affinity matrix. The decoder then reconstructs the patch using both linear and nonlinear mixing modules. In parallel, the spectral transformer tokenizes the same patch, projects the tokens into a latent space, and applies multi-head self-attention guided by the padded affinity matrix AF through an additive bias term. The classification token from the final transformer layer is fused with the abundance-derived features to produce the final logits.
Dataset
Indian Pines
Augsburg
Berlin
Sensor
AVIRIS
HySpex
EnMap
Wavelength (nm)
400–2500
400–2500
400–2500
Spatial resolution
20 m
30 m
30 m
Spatial size
145 × 145
332 × 485
1723 × 476
Spectral bands
200
180
244
Classes
16
7
8
TABLE I: Summary of the HSI datasets used in experiments.
Class Name
Train
Test
2-D CNN [ 50 ]
3-D CNN [ 9 ]
GRU [ 26 ]
ViT [ 29 ]
MorphConv [ 33 ]
SSFTT [ 31 ]
WFCG [ 28 ]
DSNet [ 21 ]
CACFTNet [ 37 ]
GraphGST [ 34 ]
MambaHSI+ [ 42 ]
S2Mamba [ 41 ]
AGSA-Net (Ours)
Forest
146
13361
85.76
93.02
81.10
82.44
93.21
95.52
91.65
93.19
98.23
87.89
95.42
87.07
94.66
Residential Area
264
30065
87.44
92.68
84.51
88.77
95.83
96.39
98.96
95.85
96.60
92.89
96.86
93.68
96.95
Industrial Area
21
3830
69.56
21.46
84.41
79.27
32.69
25.93
50.97
62.85
66.40
42.64
64.88
63.55
73.68
Low Plants
248
26609
81.39
78.29
82.25
80.51
88.75
87.02
87.33
91.28
92.86
82.89
88.76
93.47
93.99
Allotment
52
523
41.68
58.70
32.10
33.35
63.67
45.70
52.35
66.92
68.64
53.35
55.64
43.98
69.41
Commercial Area
7
1638
14.10
9.46
5.56
12.39
15.81
11.78
1.05
11.05
16.12
10.32
10.93
12.45
4.58
TABLE II: Class-wise classification accuracy (%) on the Augsburg dataset
Class
Train
Test
2-D CNN [ 50 ]
3-D CNN [ 9 ]
GRU [ 26 ]
ViT [ 29 ]
MorphConv [ 33 ]
SSFTT [ 31 ]
WFCG [ 28 ]
DSNet [ 21 ]
CACFTNet [ 37 ]
GraphGST [ 34 ]
MambaHSI+ [ 42 ]
S2Mamba [ 41 ]
AGSA-Net (Ours)
Forest
443
54511
77.16
73.10
75.55
66.74
55.24
47.84
76.46
75.44
73.55
84.93
81.42
70.24
76.51
Residential
423
268219
66.33
55.27
57.60
57.86
72.47
73.58
68.80
74.69
84.41
72.97
81.79
74.05
79.31
Industrial
499
19067
21.37
43.92
73.13
55.85
26.25
30.59
42.06
54.91
38.76
53.75
32.35
41.51
49.26
LowPlants
376
58906
69.11
68.76
71.70
76.25
74.27
84.73
67.58
81.79
62.63
86.15
73.94
75.77
89.26
Soil
331
17095
68.15
84.05
82.95
80.04
84.88
92.20
97.91
74.19
69.01
83.18
71.36
76.02
80.51
Allotment
280
13025
58.52
32.48
22.30
64.17
61.21
49.21
72.80
63.71
29.25
77.47
33.65
64.19
57.83
TABLE III: Class-wise classification accuracy (%) on the Berlin dataset
Class Name
Train
Test
2-D CNN [ 50 ]
3-D CNN [ 9 ]
GRU [ 26 ]
ViT [ 29 ]
MorphConv [ 33 ]
SSFTT [ 31 ]
WFCG [ 28 ]
DSNet [ 21 ]
CACFTNet [ 37 ]
GraphGST [ 34 ]
MambaHSI+ [ 42 ]
S2Mamba [ 41 ]
AGSA-Net (Ours)
Corn Notill
50
1384
77.24
65.25
72.33
66.55
71.53
85.62
94.87
83.96
95.88
95.81
74.57
94.44
91.04
Corn Mintill
50
784
84.57
59.57
83.16
88.52
84.57
90.43
90.69
94.90
99.74
98.85
87.63
100.00
96.56
Corn
50
184
92.39
94.57
73.37
88.59
97.83
97.28
100.00
99.46
100.00
100.00
95.65
100.00
99.46
Grass Pasture
50
447
94.63
89.71
87.02
97.09
93.74
90.60
94.41
98.21
97.76
97.09
87.92
98.43
97.32
Grass Trees
50
697
78.62
95.12
81.35
85.65
92.25
95.95
99.43
97.27
100.00
98.57
90.24
100.00
100.00
Hay Windrowed
50
439
92.26
98.63
94.76
98.86
98.86
98.63
100.00
99.54
100.00
99.54
95.67
100.00
98.41
TABLE IV: Class-wise classification accuracy (%) on the Indian Pines dataset
Fig. 3: False-color image, ground truth and classification maps obtained using the Transformer, DSNet, and AGSA-Net models on the Indian Pines dataset.
Fig. 4: False-color image, ground truth, and classification maps obtained using the Transformer, DSNet, and AGSA-Net models on the Augsburg dataset.
Fig. 5: False-color image, ground truth and classification maps obtained using the Transformer, DSNet, and AGSA-Net models on the Berlin dataset.
Fig. 6: Confusion matrices obtained using AGSA-Net on the Berlin and Augsburg datasets.
Fig. 7: Effect of training sample ratio on overall accuracy (OA) across the evaluated datasets and different models, showing performance variations under different ratios of training data.
Model
# of Params
FLOPs
Inference Time
(Millions) ↓
(Millions) ↓
(ms) ↓
DSNet [ 21 ]
0.42
11.00
0.021
SSFTT [ 31 ]
0.15
1.43
0.022
GraphGST [ 34 ]
2.14
2.15
0.094
CACFTNet [ 37 ]
1.86
118.52
0.285
ViT [ 29 ]
5.37
267.31
0.265
TABLE V: Computational complexity comparison on the Indian Pines dataset (patch size 7×7 ). ↓ denotes that lower is better. Bold indicates the best result, and underlined indicates the second-best result.
Dataset
Sim. Type
Same-Class
Different-Class
Gap
Indian Pines
Spectral
0.9939
0.9233
0.0706
Abundance
0.9562
0.8403
0.1159
Augsburg
Spectral
0.9769
0.9425
0.0344
Abundance
0.9671
0.8958
0.0713
Berlin
Spectral
0.9811
0.9535
0.0276
Abundance
0.8844
0.7857
0.0987
TABLE VI: Similarity Comparison Between Abundance and Spectral Representations
Description
Equation
Indian Pines
Augsburg
Berlin
OA
AA
κ
OA
AA
κ
OA
AA
κ
Shuffled Guidance
QK⊤+λPAabuP⊤
80.72
88.40
78.01
84.32
62.47
77.33
68.92
62.97
55.47
Spectral Guidance
QK⊤+λAspec
79.73
88.32
77.03
84.68
63.27
77.87
70.65
64.44
57.30
No Guidance
QK⊤
80.92
89.55
78.35
84.96
60.66
78.24
72.00
60.54
57.69
Proposed Abundance Guidance
QK⊤+λAabu
81.99
89.12
79.40
85.57
64.00
79.25
72.29
64.63
59.09
TABLE VII: Controlled intervention analysis of different attention guidance strategies.
Fig. 8: Visualization of abundance-guided self-attention behavior for the Augsburg (top) and Indian Pines (bottom) datasets. For each dataset, the panels show: (1) query token location, (2) attention map without guidance, (3) attention map with abundance guidance, (4) abundance similarity map, and (5) attention difference ( Δ Attention) between guided and unguided settings. The alignment score above each row denotes the correlation between the attention distribution and abundance similarity before and after introducing abundance guidance.
Modules
Remarks
Indian Pines
Augsburg
Berlin
UA
AGM
Fusion
Trans
OA
AA
κ
OA
AA
κ
OA
AA
κ
×
×
×
✓
Transformer only
81.30
89.14
78.68
82.22
56.97
74.12
68.00
62.92
50.65
✓
✓
×
✓
No abundance fusion
81.99
89.12
79.40
85.57
64.00
79.25
72.29
64.63
59.09
✓
×
✓
×
CNN backbone (DSNet)
93.08
96.31
92.08
89.30
67.20
84.62
72.09
65.34
59.27
✓
×
✓
✓
No abu-guided self-attn
94.72
97.36
93.96
90.48
67.41
86.26
76.04
64.77
63.50
✓
✓
✓
✓
AGSA-Net
96.04
97.61
95.45
91.26
68.47
87.46
75.31
65.04
63.04
TABLE VIII: Core component analysis of the proposed AGSA-Net on Indian Pines, Augsburg, and Berlin datasets.
Fig. 9: Training dynamics of the abundance guidance weight λ and validation accuracy on the Indian Pines, Augsburg, and Berlin datasets. The circle indicates the value of λ at the epoch where the best validation accuracy is achieved, while the star denotes the highest validation accuracy during training.
Dataset
Metric
0.5U
0.75U
U
1.25U
1.5U
2U
Pines
Best OA
0.9343
0.9413
0.9604
0.9431
0.9478
0.9455
Best AA
0.9645
0.9700
0.9761
0.9671
0.9694
0.9746
Kappa
0.9248
0.9328
0.9546
0.9348
0.9401
0.9376
Berlin
Best OA
0.7211
0.7187
0.7531
0.7465
0.7214
0.7503
Best AA
0.6501
0.6368
0.6504
0.6173
0.6693
0.5911
Kappa
0.5912
0.5847
0.6304
0.6170
0.5945
0.6131
TABLE IX: Sensitivity analysis of the number of endmembers ( K ). Best OA, AA and Kappa values for each dataset are highlighted in bold.
Fig. 10: t-SNE visualization of feature representations from the Indian Pines dataset using (a) raw spectral features, (b) Transformer, (c) DSNet, and (d) AGSA-Net. AGSA-Net produces the most compact and well-separated clusters, indicating more discriminative feature representations.
Although hyperspectral image (HSI) classification is critical for supporting various environmental applications, it is a challenging task due to the spectral-mixture effect, the spatial-spectral heterogeneity and the difficulty to preserve class boundaries and details. This letter presents a novel unmixing-guided spatial-spectral Mamba with clustering tokens for improved HSI classification, with the following contributions. First, to disentangle the spectral mixture effect in HSI for improved pattern discovery, we design a novel spectral unmixing network that not only automatically learns endmembers and abundance maps from HSI but also accounts for endmember variabilities. Second, to generate Mamba token sequences, based on the clusters defined by abundance maps, we design an efficient Top-K token selection strategy to adaptively sequence the tokens for improved representational capability. Third, to improve spatial-spectral feature learning and detail preservation, based on the Top-K token sequences, we design a novel unmixing-guided spatial-spectral Mamba module that greatly improves traditional Mamba models in terms of token learning and sequencing. Fourth, to learn simultaneously the endmember-abundance patterns and classification labels, a multi-task scheme is designed for model supervision, leading to a new unmixing-classification framework that outputs not only accurate classification maps but also a comprehensive spectral-library and abundance maps. Comparative experiments on four HSI datasets demonstrate that our model can greatly outperform the other state-of-the-art approaches. Code is available at https://github.com/GSIL-UCalgary/Unmixing_guided_Mamba.git
Yimin Zhu, Lincoln Linlin Xu
Department of Geomatics Engineering, University of Calgary, Canada
Over the past decade, hyperspectral image (HSI) classification has drawn considerable interest due to HSIs' ability to effectively distinguish terrestrial objects by capturing detailed, continuous spectral information. The strong performance of recent deep learning techniques in tasks like image classification and semantic segmentation has led to their growing use in HSI classification, due to their ability to capture complex spatial and spectral features more effectively than traditional methods. This paper presents MixerCA, a novel lightweight model for HSI classification that leverages depthwise convolution and a self-attention mechanism. MixerCA integrates depth-wise convolutions, token and channel mixing, and coordinate attention into a unified structure to decouple spatial and channel interactions, maintain consistent resolution throughout the network, and directly process HSI patches. Extensive experiments on four hyperspectral benchmark datasets reveal MixerCA's clear advantages over several competing algorithms, including 2D-CNN, 3D-CNN, Tri-CNN, HybridSN, ViT, and Swin Transformer. The source code is publicly available at https://github.com/mqalkhatib/MixerCA.
Mohammed Q. Alkhatib, Ali Jamali
aCollege of Engineering and IT, University of Dubai, Dubai, 14143, UAE · bDepartment of Geography, Simon Fraser University, 8888 University Dr, Burnaby, BC V5A 1S6, Canada
Hyperspectral image (HSI) and SAR/LiDAR data offer complementary spectral and structural information for land-cover classification. However, their effective fusion remains challenging due to two major limitations: The spectral redundancy in high-dimensional HSI and the heterogeneous characteristics between multi-source data. To this end, we propose Representative Spectral Correlation Network (RSCNet), a novel multi-source image classification framework specifically designed to address the above challenges through spectral selection and adaptive interaction. The network incorporates two key components: (1) Key Band Selection Module (KBSM) that adaptively selects task-relevant spectral bands from the original HSI under cross-source guidance, thereby alleviating redundancy and mitigating information loss from conventional PCA-based spectral reduction. Moreover, the learned band subset exhibits highly discriminative spectral structures that align with discriminative semantic cues, promoting compact yet expressive representations. (2) Cross-source Adaptive Fusion Module (CAFM) that performs cross-source attention weighting and local-global contextual refinement to enhance cross-source feature interaction. Experiments on three public benchmark datasets demonstrate that our RSCNet achieves superior performance compared with state-of-the-art methods, while maintaining substantially lower computational complexity. Our codes are publicly available at https://github.com/oucailab/RSCNet.
Chuanzheng Gong, Feng Gao, Junyan Lin +2
State Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao 266100, China · Department of Computing, The Hong Kong Polytechnic University, Hong Kong, China · Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762 USA