Fig. 1. Spatial feature extraction method based on multiscale local maximum
Fig. 2. Classification maps of each algorithm on Indian Pines dataset. (a) Ground truth; (b) SVM; (c) RF; (d) CNN1D; (e) CNN2D; (f) HybridSN; (g) A2S2K-ResNet; (h) LBP-RF; (i) EMP-RF; (j) MF-RF
Fig. 3. Classification maps of each algorithm on Pavia University dataset. (a) Ground truth; (b) SVM; (c) RF; (d) CNN1D; (e) CNN2D; (f) HybridSN; (g) A2S2K-ResNet; (h) LBP-RF; (i) EMP-RF; (j) MF-RF
Fig. 4. Number of operations in the classification process of each algorithm. (a) Spectral algorithms; (b) one-stage spatial-spectral algorithms; (c) two-stage spatial-spectral algorithms
Fig. 5. Energy consumption of each algorithm in the classification process. (a) Spectral algorithms; (b) one-stage spatial-spectral algorithms; (c) two-stage spatial-spectral algorithms
Algorithm | Number of operations |
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Exp | Mul | Add | Cmp |
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Spectral algorithm(k:number of features,l:number of classes) | SVM | M | kM+2M | kM+l | | M:number of support vectors | RF | | | N | DN | :average depth of trees,:number of trees | CNN1D | | | | | :number of values in each filter | One-stage spatial-spectral algorithm (K:kernel size, Cin:number of input channels, Cout:number of output channels) | Each convolution layer | | | | | Two-stage spatial-spectral algorithm(:number of features) | LBP-RF | | | | | :number of points in LBP,:same as RF | EMP-RF | | | | | :number of Mul/Add in PCA,:size of each structuring element,:number of structuring elements,:same as RF | MF-RF | | | | | :radius of the largest filter,:same as RF |
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Table 1. Statistics of operation type and number of operations of different algorithms
Class | Spectral algorithm | One-stage spatial-spectral algorithm | Two-stage spatial-spectral algorithm |
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SVM | RF | CNN1D | CNN2D | HybridSN | A2S2K-ResNet | LBP-RF | EMP-RF | MF-RF |
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Alfalfa | 81.82 | 100.00 | 87.50 | 100.00 | 80.49 | 100.00 | 95.24 | 97.83 | 91.84 | Corn-notil | 78.91 | 73.58 | 73.38 | 90.24 | 95.10 | 97.78 | 82.34 | 94.76 | 95.49 | Corn-mintill | 80.69 | 75.93 | 75.30 | 90.85 | 99.46 | 98.69 | 88.00 | 95.17 | 94.72 | Corn | 63.14 | 59.60 | 79.31 | 87.98 | 93.90 | 96.27 | 74.05 | 83.87 | 93.81 | Grass-pasture | 92.83 | 88.70 | 91.39 | 93.95 | 98.16 | 99.31 | 97.17 | 94.00 | 96.21 | Grass-trees | 85.24 | 82.98 | 94.59 | 93.98 | 99.24 | 99.44 | 88.18 | 97.90 | 95.45 | Grass-pasture-mowed | 83.87 | 100.00 | 95.00 | 100.00 | 100.00 | 92.22 | 90.00 | 100.00 | 89.66 | Hay-windrowed | 92.59 | 86.34 | 93.25 | 98.73 | 99.53 | 99.32 | 94.43 | 100.00 | 97.95 | Oats | 100.00 | 100.00 | 100.00 | 90.91 | 61.11 | 84.65 | 100.00 | 100.00 | 100.00 | Soybean-notill | 80.05 | 72.25 | 82.65 | 91.12 | 98.17 | 97.56 | 92.16 | 92.94 | 95.96 | Soybean-mintill | 77.97 | 73.37 | 69.97 | 94.80 | 99.05 | 99.13 | 86.45 | 94.68 | 96.16 | Soybean-clean | 77.26 | 66.60 | 85.78 | 92.58 | 90.26 | 98.10 | 87.74 | 89.64 | 92.95 | Wheat | 90.13 | 90.91 | 94.34 | 95.71 | 95.14 | 99.20 | 100.00 | 100.00 | 98.51 | Woods | 93.25 | 93.06 | 93.31 | 96.48 | 99.47 | 99.29 | 99.37 | 99.21 | 99.61 | Buildings-Grass-Trees-Drives | 73.82 | 58.43 | 71.70 | 96.21 | 95.97 | 98.00 | 97.49 | 94.33 | 98.21 | Stone-Steel-Towers | 98.77 | 98.75 | 100.00 | 78.38 | 90.48 | 96.30 | 92.86 | 97.89 | 98.78 | OA | 82.34 | 77.62 | 80.11 | 93.43 | 97.44 | 98.57 | 89.66 | 95.15 | 96.26 | AA | 84.39 | 82.53 | 86.72 | 93.24 | 93.47 | 97.20 | 91.59 | 95.76 | 95.96 | Kappa | 79.75 | 74.26 | 77.01 | 92.50 | 97.08 | 98.37 | 88.14 | 94.46 | 95.73 |
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Table 2. Classification results on Indian Pines dataset
Class | Spectral algorithm | One-stage spatial-spectral algorithm | Two-stage spatial-spectral algorithm |
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SVM | RF | CNN1D | CNN2D | HybridSN | A2S2K-ResNet | LBP-RF | EMP-RF | MF-RF |
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Asphalt | 93.60 | 92.03 | 95.15 | 98.75 | 100.00 | 99.76 | 97.12 | 99.40 | 98.68 | Meadows | 96.17 | 90.22 | 98.17 | 99.33 | 100.00 | 99.95 | 98.65 | 99.82 | 99.30 | Gravel | 88.38 | 86.50 | 89.82 | 97.90 | 98.68 | 99.42 | 96.69 | 99.86 | 98.76 | Trees | 96.25 | 96.21 | 95.10 | 96.19 | 99.45 | 99.88 | 97.10 | 99.90 | 99.14 | Painted metal sheets | 99.04 | 98.23 | 99.63 | 99.56 | 100.00 | 99.97 | 99.48 | 100.00 | 99.85 | Bare Soil | 94.65 | 92.93 | 91.94 | 99.26 | 100.00 | 99.96 | 98.26 | 99.94 | 99.80 | Bitumen | 92.73 | 86.11 | 92.05 | 92.81 | 100.00 | 100.00 | 99.13 | 99.70 | 99.62 | Self-Blocking Bricks | 86.00 | 82.08 | 85.33 | 97.48 | 99.70 | 99.00 | 93.86 | 99.08 | 99.17 | Shadows | 100.00 | 100.00 | 99.37 | 99.55 | 94.60 | 100.00 | 99.79 | 99.68 | 99.79 | OA | 94.41 | 90.56 | 95.07 | 98.58 | 99.72 | 99.81 | 97.81 | 99.71 | 99.25 | AA | 94.09 | 91.59 | 94.06 | 97.87 | 99.11 | 99.77 | 97.79 | 99.71 | 99.35 | Kappa | 92.56 | 87.26 | 93.48 | 98.12 | 99.63 | 99.75 | 97.10 | 99.62 | 99.01 |
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Table 3. Classification results on Pavia University dataset
Dataset | Spectral algorithm | One-stage spatial-spectral algorithm | Two-stage spatial-spectral algorithm |
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SVM | RF | CNN1D | CNN2D | HybridSN | A2S2K- ResNet | LBP-RF | EMP-RF | MF-RF |
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Indian Pines | 3.41 | 0.54 | 1.20 | 6.11 | 72.30 | 45.68 | 4.38 | 1.48 | 1.07 | Pavia University | 39.23 | 4.15 | 7.43 | 59.56 | 277.31 | 117.42 | 79.70 | 12.69 | 16.69 |
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Table 4. Classification times of different algorithms on two datasets
Class | RF | L1+RF | ST+RF | ST+CORAL+RF | MF-RF(17) | ST+CORAL+MF-RF(52) |
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Dense Urban Fabric | 5.78 | 29.17 | 4.39 | 3.70 | 8.21 | 15.49 | Mineral Extraction Sites | 0.00 | 17.07 | 16.24 | 34.09 | 2.50 | 33.33 | Non-Irrigated Arable Land | 25.00 | 83.14 | 45.71 | 92.18 | 66.67 | 76.61 | Fruit Trees | 0.00 | 0.00 | 1.52 | 3.05 | 0.00 | 1.96 | Olive Groves | 2.22 | 44.44 | 0.00 | 81.40 | 0.00 | 62.63 | Coniferous Forest | 100.00 | 87.50 | 64.60 | 39.49 | 85.71 | 28.15 | Dense Sclerophyllous Vegetation | 67.54 | 67.88 | 68.45 | 71.68 | 66.59 | 69.38 | Sparce Sclerophyllous Vegetation | 44.33 | 37.46 | 51.43 | 49.70 | 45.65 | 51.60 | Sparcely Vegetated Areas | 9.38 | 11.66 | 4.99 | 17.28 | 9.29 | 17.92 | Rocks and Sand | 9.45 | 28.00 | 56.91 | 57.32 | 8.93 | 58.40 | Water | 62.28 | 95.15 | 100.00 | 100.00 | 67.64 | 100.00 | Coastal Water | 3.01 | 100.00 | 100.00 | 99.34 | 2.15 | 96.16 | OA | 46.66 | 51.99 | 55.45 | 58.59 | 48.57 | 60.03 | AA | 27.42 | 50.12 | 42.85 | 54.10 | 30.28 | 50.97 | Kappa | 33.13 | 41.27 | 45.95 | 49.92 | 35.52 | 50.67 |
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Table 5. Classification results on HyRANK dataset
Dataset | PSNR /dB | RF | CNN1D | MF-RF(minimum) | MF-RF(maximum) |
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Indian Pines | | 77.62 | 80.11 | 93.76 | 96.26 | 36.38 | 77.10 | 80.07 | 93.27 | 95.07 | 26.38 | 74.14 | 76.19 | 93.04 | 94.67 | Pavia University | | 90.56 | 95.07 | 99.06 | 99.25 | 35.07 | 89.94 | 93.61 | 98.80 | 99.28 | 25.07 | 85.79 | 87.77 | 97.94 | 99.31 |
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Table 6. Classification results of RF, CNN1D, and MF-RFs based on different feature values
Dataset | MF-SVM | MF-FC | MF-RF |
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Indian Pines | OA | 94.89 | 79.61 | 96.26 | AA | 95.60 | 76.72 | 95.96 | Kappa | 94.17 | 76.62 | 95.73 | Pavia University | OA | 99.47 | 90.46 | 99.25 | AA | 99.49 | 89.13 | 99.35 | Kappa | 99.29 | 87.33 | 99.01 |
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Table 7. Comparison of MF and different classifiers combinations
Dataset | CNN1D-RF | CNN2D-RF | MF-RF |
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Indian Pines | OA | 80.88 | 92.53 | 96.26 | AA | 87.78 | 93.65 | 95.96 | Kappa | 77.93 | 91.44 | 95.73 | Pavia University | OA | 95.37 | 97.93 | 99.25 | AA | 95.19 | 97.79 | 99.35 | Kappa | 93.83 | 97.25 | 99.01 |
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Table 8. Comparison of different CNN feature extraction methods and RF combinations
Operation type | Data precision /bit | Energy cost /pJ |
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Integer comparison | 8 | 0.008 | Floating-point addition | 32 | 0.9 | Floating-point multiplication | 32 | 3.7 | Floating-point exponentiation | 32 | 38.975 |
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Table 9. Energy consumption of different operation types
Classification algorithm | Indian Pines | Pavia University |
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SVM | 2.8×107 | 2.4×107 | RF | 1.0×102 | 1.1×102 | CNN1D | 7.2×105 | 3.1×105 | CNN2D | 1.8×108 | 1.3×108 | HybridSN | 1.1×109 | 1.1×109 | A2S2K-ResNet | 7.7×1010 | 3.8×1010 | LBP-RF | 1.1×102 | 1.3×102 | EMP-RF | 5.4×107 | 1.8×106 | MF-RF | 2.7×102 | 1.0×103 |
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Table 10. Energy consumption of each algorithm in classification process