Digital Inspection Technology for Sheet Metal Parts Using 3D Point Clouds
Abstract
1. Introduction
2. Digital Inspection Method for Sheet Metal Parts Using 3D Point Clouds
2.1. Acquisition and Preprocessing of Point Cloud Data of Sheet Metal Parts
- ①
- Pass-Through Filtering Algorithm
- ②
- Downsampling and Processing for Improved Voxel Grid Filtering
- (1)
- Suppose that the original point cloud data set P contains N data coordinate points, and the voxel grid method is adopted to perform downsampling on the point cloud data.
- (2)
- Calculate the centroid coordinate points, p(x, y, z), of each non-empty voxel grid and construct a new set of centroid points, pi(xi, yi, zi).
- (3)
- Search each voxel grid according to the KD tree nearest neighbor search method and take the point closest to the centroid in it as the new downsampled point to obtain a new set of centroid points, pi.
2.2. Point Cloud Registration of Sheet Metal Parts
2.2.1. Rough Registration of Point Clouds
- ①
- A local coordinate system is established for each point pi in the point cloud data, and a search radius r is set for all points. An appropriate search radius r needs to be selected based on the actual situation, such as the density of the point cloud.
- ②
- Query all points in the area of radius r centered on each point pi in point cloud data P and calculate the weights wij of these points, as shown in Equation (1):
- ③
- Calculate the covariance matrix of each point pi, as shown in Equation (2):
- ④
- Calculate the eigenvalues of covariance matrix cov(pi) for each point pi in the point cloud data and arrange them in order from largest to smallest.
- ⑤
- Set the threshold values and , and the points that meet the screening conditions of Equation (3) are ISS feature points.
2.2.2. ICP Fine Registration
2.3. A 3D Reconstruction Algorithm for Sheet Metal Parts
2.3.1. Greedy Projection Triangulation Processing
2.3.2. Poisson Surface Reconstruction Processing
2.3.3. MLS Smoothing Processing
3. Digital Detection Experiments on Sheet Metal Parts Based on 3D Point Clouds
3.1. Experiments on Point Cloud Denoising of Sheet Metal Parts
3.2. Registration Experiments on Sheet Metal Parts
3.3. Three-Dimensional Reconstruction Experiments on Sheet Metal Parts
3.4. Digital Detection Experiments on Sheet Metal Parts
3.4.1. Digital Detection Algorithm
3.4.2. Projection Experiments on Sheet Metal Parts
3.4.3. Experiments on Dimension Measurement of Sheet Metal Parts
4. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Device Model | EinScan Pro 2X |
---|---|
Scanning precision | 0.045 mm |
Scanning range per single scan | 150 × 120 mm~250 × 200 mm |
Working center distance | 400 mm |
Printable data output format | OBJ, STL, ASC, PLY, P3, 3MF |
Weight of scanning head | 1.13 kg |
System requirements | Windows 10, 64-bit |
Serial Number | Number of Point Clouds | λ | k | Number of Point Clouds After Noise Reduction |
---|---|---|---|---|
(a) | 20,463 | 0.05 | 1 | 13,713 |
(b) | 20,463 | 0.1 | 1 | 14,120 |
(c) | 20,463 | 0.5 | 1 | 16,552 |
(d) | 20,463 | 1 | 1 | 17,901 |
(e) | 20,463 | 1.5 | 1 | 18,674 |
(f) | 20,463 | 2 | 1 | 19,253 |
Serial Number | Number of Point Clouds | λ | k | Number of Point Clouds After Noise Reduction |
---|---|---|---|---|
(a) | 17,901 | 1 | 1 | 17,901 |
(b) | 17,901 | 1 | 2 | 17,761 |
(c) | 17,901 | 1 | 3 | 17,687 |
(d) | 17,901 | 1 | 4 | 17,622 |
(e) | 17,901 | 1 | 5 | 17,617 |
(f) | 17,901 | 1 | 6 | 17,616 |
Algorithm | Number of Point Clouds |
---|---|
Initial point clouds | 17,617 |
Downsampling by the voxel grid algorithm | 3359 |
Downsampling by the improved algorithm | 3359 |
Algorithm | Number of Iterations | Registration Error (m) | Time (s) |
---|---|---|---|
ICP algorithm | 4 | 8.00264 × 10−5 | 5.936 |
8 | 1.93961 × 10−5 | 8.453 | |
12 | 5.56931 × 10−6 | 10.867 | |
16 | 1.23578 × 10−6 | 13.349 | |
20 | 6.96264 × 10−7 | 15.896 | |
24 | 2.63578 × 10−7 | 18.345 | |
Improved algorithm | 1 | 2.46069 × 10−6 | 11.522 |
2 | 2.03659 × 10−6 | 11.572 | |
3 | 1.60361 × 10−6 | 11.634 | |
4 | 1.18995 × 10−6 | 11.681 | |
5 | 7.51249 × 10−7 | 11.736 | |
6 | 4.22656 × 10−7 | 11.793 |
Algorithm | Number of Iterations | Registration Error (m) | Time (s) |
---|---|---|---|
ICP algorithm | 4 | 7.07786 × 10−5 | 5.032 |
8 | 1.89264 × 10−5 | 7.982 | |
12 | 6.68919 × 10−6 | 10.975 | |
16 | 1.52197 × 10−6 | 14.063 | |
20 | 5.69119 × 10−7 | 17.192 | |
24 | 2.03491 × 10−7 | 20.038 | |
Improved algorithm | 1 | 2.59116 × 10−6 | 10.581 |
2 | 2.10359 × 10−6 | 10.623 | |
3 | 1.68134 × 10−6 | 10.674 | |
4 | 1.20319 × 10−6 | 10.716 | |
5 | 8.76916 × 10−7 | 10.759 | |
6 | 4.95649 × 10−7 | 10.807 |
Algorithm | Time (s) |
---|---|
Greedy triangulation algorithm | 4.368 |
Poisson algorithm | 4.136 |
Improved algorithm | 4.697 |
Size Name | Value Measured by the Universal Tool Microscope (mm) | Pixel Value |
---|---|---|
d1 | 95.9941 | 1517 |
d2 | 43.9887 | 695 |
Dimension Annotation | Value Measured by the Universal Tool Microscope (mm) | Measured Value (mm) | Error (mm) |
---|---|---|---|
h1 | 80.0129 | 80.2011 | 0.1882 |
h2 | 80.0067 | 80.2644 | 0.2577 |
h3 | 80.0117 | 80.2011 | 0.1894 |
h4 | 79.9962 | 80.1378 | 0.1416 |
d1 | 15.0165 | 14.8122 | 0.2043 |
d2 | 15.0097 | 15.1922 | 0.1825 |
d3 | 15.0126 | 14.7489 | 0.2637 |
d4 | 15.0203 | 15.2553 | 0.2350 |
h5 | 20.0105 | 20.2562 | 0.2457 |
h6 | 20.0107 | 19.7496 | 0.2611 |
h7 | 20.0096 | 20.1927 | 0.1831 |
h8 | 20.0148 | 20.1927 | 0.1779 |
Dimension Annotation | Value Measured by the Universal Tool Microscope (mm) | Measured Value (mm) | Error (mm) |
---|---|---|---|
h1 | 120.0026 | 120.2067 | 0.2041 |
h2 | 80.0103 | 80.2011 | 0.1908 |
h3 | 120.0067 | 120.2704 | 0.2637 |
h4 | 79.9972 | 80.2644 | 0.2672 |
h5 | 18.0065 | 18.2304 | 0.2239 |
h6 | 18.0112 | 18.1671 | 0.1559 |
h7 | 18.0130 | 17.8506 | 0.1624 |
h8 | 17.9826 | 18.1671 | 0.1845 |
h9 | 20.0192 | 20.2560 | 0.2368 |
h10 | 19.9763 | 20.1927 | 0.2164 |
h11 | 20.0125 | 20.1927 | 0.1802 |
d1 | 40.0070 | 40.2588 | 0.2518 |
d2 | 20.0108 | 19.7496 | 0.2612 |
d3 | 10.0203 | 10.2546 | 0.2343 |
Dimension Annotation | Value Measured by the Universal Tool Microscope (mm) | Measured Value (mm) | Error (mm) |
---|---|---|---|
h1 | 120.0116 | 120.2067 | 0.1951 |
h2 | 80.0126 | 80.2011 | 0.1885 |
h3 | 119.9776 | 120.1434 | 0.1658 |
h4 | 79.9863 | 80.1378 | 0.1515 |
h5 | 20.0067 | 20.2561 | 0.2494 |
h6 | 15.0026 | 15.2553 | 0.2527 |
h7 | 15.0120 | 15.1924 | 0.1804 |
h8 | 14.9773 | 15.1287 | 0.1514 |
h9 | 17.9926 | 17.7242 | 0.2684 |
h10 | 15.0028 | 14.8122 | 0.1906 |
h11 | 15.0102 | 15.2553 | 0.2451 |
h12 | 15.0113 | 14.8126 | 0.1987 |
h13 | 21.0036 | 20.8257 | 0.1779 |
h14 | 15.0096 | 15.2553 | 0.2457 |
h15 | 15.0198 | 14.8755 | 0.1443 |
h16 | 15.0114 | 14.8122 | 0.1992 |
h17 | 15.9727 | 16.2048 | 0.2321 |
d1 | 8.0076 | 7.8492 | 0.1584 |
d2 | 8.0103 | 8.2290 | 0.2187 |
d3 | 8.0060 | 8.1657 | 0.1597 |
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Guo, J.; Tan, D.; Guo, S.; Chen, Z.; Liu, R. Digital Inspection Technology for Sheet Metal Parts Using 3D Point Clouds. Sensors 2025, 25, 4827. https://doi.org/10.3390/s25154827
Guo J, Tan D, Guo S, Chen Z, Liu R. Digital Inspection Technology for Sheet Metal Parts Using 3D Point Clouds. Sensors. 2025; 25(15):4827. https://doi.org/10.3390/s25154827
Chicago/Turabian StyleGuo, Jian, Dingzhong Tan, Shizhe Guo, Zheng Chen, and Rang Liu. 2025. "Digital Inspection Technology for Sheet Metal Parts Using 3D Point Clouds" Sensors 25, no. 15: 4827. https://doi.org/10.3390/s25154827
APA StyleGuo, J., Tan, D., Guo, S., Chen, Z., & Liu, R. (2025). Digital Inspection Technology for Sheet Metal Parts Using 3D Point Clouds. Sensors, 25(15), 4827. https://doi.org/10.3390/s25154827