Author Affiliations
School of Resources and Environmental, Wuhan University of Technology, Wuhan, Hubei 430079, Chinashow less
Fig. 1. Schematic of spatial dynamic grid Q
Fig. 2. Schematic of projection of Pi and k neighbor points onto their micro-cut plane
Fig. 3. Local two-dimensional coordinate system established in micro-cut plane
Fig. 4. Unitized projection vector. (a) Neighborhood points tilted to one side (boundary feature point); (b) neighborhood points distributed evenly (internal point)
Fig. 5. Using vector deflection angle to select next connection point
Fig. 6. Problems during vector deflection angle sorting. (a) Question 1; (b) question 2
Fig. 7. Schematic of traditional cubic B-spline algorithm
Fig. 8. Schematic of improved cubic B-spline algorithm
Fig. 9. Fitting connection comparison by three methods. (a) Circle; (b) sinusoid
Fig. 10. Partial extraction effect diagrams under different parameters. (a) k=30, ε=0.48; (b) k=30, ε=0.52; (c) k=28, ε=0.50; (d) k=30, ε=0.50
Fig. 11. Feature extraction comparison and fitting of point cloud model. (a)(f)(k) Original point clouds; (b)(g)(l) algorithmin Ref. [11]; (c)(h)(m) algorithm in Ref. [12]; (d)(i)(n) proposed algorithm; (e)(j)(o) feature regularization
Fig. 12. Feature extraction and fitting of Yangtze River Erqi Bridge. (a) Side view; (e) main view; (i) top view; (b)(f)(j) algorithm in Ref. [12]; (c)(g)(k) proposed algorithm; (d)(h)(l) feature regularization
ε | k=26 | k=28 | k=30 |
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Feature pointnumber | Runningtime /ms | Feature pointnumber | Runningtime /ms | Feature pointnumber | Runningtime /ms |
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0.48 | 378 | 3041 | 357 | 3141 | 400 | 3216 | 0.50 | 321 | 2987 | 304 | 3125 | 340 | 3244 | 0.52 | 271 | 2972 | 254 | 3123 | 285 | 3198 |
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Table 1. Extraction status of feature points and running time under different parameters
Sculpture point cloud model | Original point number | Feature point number | Extraction rate /% | Running time /s |
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Algorithm of Ref. [12] | 72902 | 7697 | 10.6 | 18.34 | Proposed algorithm | 72902 | 12095 | 16.6 | 12.57 |
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Table 2. Extraction status of feature points and running time by two algorithms
Position | μ /mm |
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Bridge body | 0.0472 | 0.0063 | 0.0389 | 0.0412 | 0.0682 | 0.0561 | 0.1068 | 0.0231 | 0.0561 | 0.0968 | | 0.0210 | 0.0178 | 0.0492 | 0.0639 | 0.1078 | 0.1134 | 0.0892 | 0.0634 | 0.0548 | 0.1249 | Hook | 0.0437 | 0.0894 | 0.0947 | 0.1069 | 0.1127 | 0.0357 | 0.0368 | 0.0479 | 0.1018 | 0.0294 | | 0.0417 | 0.0396 | 0.1034 | 0.0147 | 0.1058 | 0.0369 | 0.0647 | 0.1249 | 0.1078 | 0.1095 |
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Table 3. Deviations between randomly selected 40 points and boundary lines