Fig. 1. Schematic of dataset amplification of bridge crack images. (a) Original image; (b) horizontal flip; (c) vertical flip; (d) linear transformation; (e) spatial filtering transformation
Fig. 2. Generative model
Fig. 3. Discriminant model
Fig. 4. Schematic of 4-layer DenseBlock
Fig. 5. Schematic of detection of high-resolution image
Fig. 6. Visualization comparison of cracks generated by DCGAN and BCIGM. (a) Nepoch=01; (b) Nepoch=03; (c) Nepoch=16; (d) Nepoch=25
Fig. 7. Visualization comparison of cracks generated by ReLU and SeLU. (a) Nepoch=01; (b) Nepoch=03; (c) Nepoch=16; (d) Nepoch=25
Fig. 8. Visualization comparison of experimental results with and without dataset amplification. (a) Original image; (b)label; (c) without dataset amplification; (d) with dataset amplification
Fig. 9. Comparison of crack detection results between existing algorithms and proposed algorithm. (a) Original image; (b) label; (c) threshold segmentation algorithm; (d) Canny algorithm; (e) NB-CNN algorithm; (f) random structure forest algorithm; (g) proposed algorithm
Fig. 10. Partial crack detection results by proposed algorithm. (a) Scene 1; (b) scene 2; (c) scene 3
Name oflayer | Size ofkernel /(pixel×pixel) | Stride /pixel | Size of output featuremap /(pixel×pixel) | Number offeature map |
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Inputlayer | - | - | 256×256 | 3 | Convolution | Convolution 5×5 | 1 | 256×256 | 48 | DenseBlock | Convolution [3×3]×4 | 1 | 256×256 | 96 | Transition Down | Convolution 1×1 | 1 | 256×256 | 96 | Max pooling 2×2 | 2 | 128×128 | 96 | DenseBlock | Convolution [3×3]×5 | 1 | 128×128 | 156 | Transition Down | Convolution 1×1 | 1 | 128×128 | 156 | Max pooling 2×2 | 2 | 64×64 | 156 | DenseBlock | Convolution [3×3]×7 | 1 | 64×64 | 240 | Transition Down | Convolution 1×1 | 1 | 64×64 | 240 | Max pooling 2×2 | 2 | 32×32 | 240 | DenseBlock | Convolution [3×3]×10 | 1 | 32×32 | 360 | Transition Down | Convolution 1×1 | 1 | 32×32 | 360 | Max pooling 2×2 | 2 | 216×16 | 360 | DenseBlock | Convolution [3×3]×12 | 1 | 16×16 | 504 | Transition Up | Deconvolution 3×3 | 2 | 32×32 | 504 | DenseBlock | Convolution [3×3]×10 | 1 | 32×32 | 624 | Transition Up | Deconvolution 3×3 | 2 | 64×64 | 624 | DenseBlock | Convolution [3×3]×7 | 1 | 64×64 | 444 | Transition Up | Deconvolution 3×3 | 2 | 128×128 | 444 | DenseBlock | Convolution [3×3]×5 | 1 | 128×128 | 300 | Transition Up | Deconvolution 3×3 | 2 | 256×256 | 300 | DenseBlock | Convolution [3×3]×4 | 1 | 256×256 | 204 | Convolution | Convolution 1×1 | 1 | 256×256 | 2 | Softmax | - | - | - | - |
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Table 1. Network structure parameters of BCISM
Type ofpicture | Simplebackground | Backgroundwith obstacles | Backgroundwith largearea of stains |
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Number ofpictures | 10449 | 13275 | 5710 | Proportion /% | 35.5 | 45.1 | 19.4 |
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Table 2. Proportion of number of different types of images in total dataset
Condition | Time /s |
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Without 1×1 convolution kernel | 5.4801 | With 1×1 convolution kernel | 5.4312 |
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Table 3. Influence of BCIGM on training speed under different conditions
Number oftraining samples | With or withoutdataset amplification | Number ofverification samples | PPrecision /% | PRecall /% |
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1183 | Without dataset amplification | 156 | 13.5 | 17.9 | 29434 | With dataset amplification | 156 | 92.9 | 92.6 |
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Table 4. Effect of dataset amplification on experimental results
Model | Pre-training | Parameter /M | PPrecision /% | PRecall /% | PF1_Score /% | Time /s |
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SegNet | True | 29.5 | 74.0 | 78.5 | 76.2 | 0.5823 | FCN8 | True | 134.5 | 86.9 | 83.4 | 85.1 | 0.3739 | DeepLab | True | 37.3 | 82.6 | 80.9 | 81.7 | 0.9751 | FC-DenseNet56 (k=12) | False | 1.5 | 89.8 | 87.6 | 88.7 | 0.1685 | FC-DenseNet67 (k=16) | False | 3.5 | 89.0 | 88.8 | 88.9 | 0.2635 | FC-DenseNet103 (k=16) | False | 9.4 | 93.0 | 92.1 | 92.5 | 0.2795 | BCISM (k=12) | False | 2.8 | 92.9 | 92.6 | 92.8 | 0.1998 |
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Table 5. Comparison of exiting semantic segmentation models and BCISM