Author Affiliations
1School of Electromechanical Engineering, Pingxiang University, Pingxiang 337055, Jiangxi, China2State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing 100083, Chinashow less
Fig. 1. One-dimensional image entropy changes of light stripe image set
Fig. 2. Local contrast changes of light stripe image set
Fig. 3. Definition coefficient changes of light stripe image set
Fig. 4. Synchronous changes of light stripe image set's H, C, β,and stripe centers extraction deviation Ra
Fig. 5. Light stripe imaging results of metal plate under different exposure time t. (a) t=200 μs; (b) t=1000 μs; (c) t=2000 μs; (d) t=2500 μs; (e) t=5000 μs
Fig. 6. Hign-precision rack
Fig. 7. 3D measurement results of 7th tooth in high-precision rack. (a) 3D reconstruction of tooth profile; (b) Rssa varies with t
Characteristic parameter | High quality light stripe image | Poor quality light stripe image |
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Region #2 | Region #1 | Region #3 |
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Exposure time t /μs | 500-4000 | 100-500 | 4000-15000 | One-dimensional image entropy H | 2.73-5.46 | 1.68-2.73 | 5.46-7.06 | Image local contrast C | 0.5-0.7 | 0.7-1.0 | 0-0.5 |
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Table 1. Corresponding t and H ranges of light stripe imaging quality empirical evaluation results
Evaluation parameter | Value range |
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Exposure time t /μs | 1200 ≤ t ≤ 2700 | One-dimensional image entropy H | 3.81 ≤ H ≤ 4.90 | Image local contrast C | 0.50 ≤ C ≤ 0.56 | Light stripe definition coefficient β | 0.95 ≤ β ≤ 1.00 | Stripe centers extraction deviation Ra | 0.26 ≤ Ra ≤ 0.30 |
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Table 2. Value ranges of H, C, β,and Ra of high quality light stripe images in image set U
Exposure time t /μs | One-dimensional image entropy H | Image local contrast C | Light stripe definition coefficient β | Comprehensive evaluation result E |
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200 | 2.49 | 0.98 | 0.31 | 35.2 | 1000 | 3.98 | 0.56 | 0.94 | 97.2 | 2000 | 4.64 | 0.51 | 0.95 | 98.4 | 2500 | 4.91 | 0.50 | 0.93 | 96.3 | 5000 | 6.23 | 0.46 | 0.85 | 70.8 |
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Table 3. Multi-parameters comprehensive evaluation results of light stripe images in Fig. 5
Method | Relevant evaluation parameter | Exposure time t /μs | Variation range of Rssa |
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Method 1 | α≈4.5 | 2600~3200 | 0.057~0.090 | Method 2 | R≈160,D≈2100 | 800~2000 | 0.022~0.120 | Method 3 | Llaser≈210 | 2200~3000 | 0.034~0.060 | Proposed method | 3.81 ≤ H ≤ 4.10,0.52 ≤ C ≤ 0.56,0.95 ≤ β ≤ 1.00 | 1200~2400 | 0.022~0.042 |
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Table 4. Comparison of evaluation results of different methods