Double-Threshold Segmentation of Panicle and Clustering Adaptive Density Estimation for Mature Rice Plants Based on 3D Point Cloud
Abstract
:1. Introduction
2. Materials and Methods
2.1. LiDAR Measurement System and Point-Cloud-Data Acquisition
2.1.1. LiDAR Measurement System
2.1.2. Point-Cloud-Data Acquisition
2.2. Segmentation of Clumping Mature Rice Panicle with Double-Threshold
2.2.1. Noise Reduction
2.2.2. Segmentation for Point-Cloud Data of Panicle
2.3. Clustering Adaptive-Parameter Adjustment and Rice-Density Estimation
2.3.1. Rice-Density Estimation: Supervoxel Clustering Method
2.3.2. Rice-Density Estimation: Mean-Shift Clustering Method
3. Results and Discussion
3.1. Adaptive-Parameter Adjustment Model
3.2. Noise Reduction and Double-Threshold Segmentation
3.3. Rice-Density Estimation
4. Conclusions
- (1)
- The 3D cloud point data of the rice in the field were obtained by the established LiDAR measurement system, of which the noise points far away from the target body were effectively reduced through SOR algorithm. The accurate segmentation of mature rice panicle was realized according to the elevation and reflection intensity value of the point-cloud data based on Otsu. This method could be valuable for technical reference of the similar crops segmentation, such as wheat and millet.
- (2)
- In order to better investigate the influence between the seed-point distance and the kernel bandwidth with regard to the number of points in the total panicle point cloud, respectively, when using supervoxel clustering and mean-shift clustering, the rice samples with different densities were set manually as a standard experiment group. The models were then obtained, which could be beneficial for adaptively adjusting parameters when estimating crop density.
- (3)
- The random experiment group with random density samples was established, and the measurement tests proved the proposed methods for crop-density estimation feasible based on the double-threshold segmentation method. The best results were obtained with the mean-shift clustering, resulting in an RMSE of 9.968 and a MAPE of 3.37%.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Performance Target | Parameter | Performance Target | Parameter |
---|---|---|---|
Number of laser lines | 16 | Horizontal angle resolution/° | 0.1–0.4 |
Range/mm | <100 | Frequency/Hz | 5–20 |
Accuracy/cm | ±3 | Working voltage/V | 9–32 |
Vertical angle resolution/° | 2 | Weight/g | 830 |
Horizontal measurement angle range/° | 360 | Dimensions/mm | 103×72 |
Wavelength/nm | 903 | Power/W | 8 |
Laser beam size/mm | 9.5 × 12.7 | Divergence angle/mrad | 3.0 |
Performance Target | Parameter |
---|---|
Output frequency of IMU/Hz | 200 |
Output frequency of GNSS/Hz | 20 |
Course accuracy/ | 0.05 |
Elevation angle and roll accuracy/° | 0.015 |
Input voltage/V | 10–30 |
Number | Mark | Voxel Size (mm) | Seed-Point Spacing (mm) | Number of Point Clouds in Point Cloud | Actual Results, Plants/m2 | Clustering Results, Plants/m2 |
---|---|---|---|---|---|---|
Sample-set 1 | a | 20 | 200 | 11,310 | 100 | 105 |
b | 20 | 190 | 12,780 | 97 | ||
c | 20 | 210 | 12,309 | 108 | ||
Sample-set 2 | a | 20 | 160 | 15,451 | 200 | 207 |
b | 20 | 160 | 17,460 | 205 | ||
c | 20 | 170 | 16,997 | 194 | ||
Sample-set 3 | a | 20 | 140 | 18,633 | 300 | 311 |
b | 20 | 130 | 21,055 | 323 | ||
c | 20 | 140 | 21,152 | 307 | ||
Sample-set 4 | a | 20 | 120 | 26,780 | 400 | 381 |
b | 20 | 110 | 30,261 | 396 | ||
c | 20 | 110 | 30,138 | 405 |
Number | Mark | Kernel Bandwidth (mm) | Number of Points Clouds in Point Cloud | Actual Results, Plant/m2 | Clustering Result, Plants/m2 |
---|---|---|---|---|---|
Sample-set 1 | a | 45 | 11,310 | 100 | 96 |
b | 44 | 12,780 | 104 | ||
c | 45 | 12,309 | 98 | ||
Sample-set 2 | a | 38 | 15,451 | 200 | 193 |
b | 38 | 17,460 | 191 | ||
c | 40 | 16,997 | 189 | ||
Sample-set 3 | a | 33 | 18,633 | 300 | 287 |
b | 33 | 21,055 | 292 | ||
c | 32 | 21,152 | 310 | ||
Sample-set 4 | A | 30 | 26,780 | 400 | 392 |
B | 30 | 30,261 | 412 | ||
C | 29 | 30,138 | 415 |
Number | Mark | Actual Result, Plants/m2 | Supervoxel Clustering Result, Plants/m2 | Mean-Shift Clustering Result, Plants/m2 |
---|---|---|---|---|
Sample-test 1 | a | 404 | 437 | 406 |
b | 421 | 409 | ||
c | 410 | 401 | ||
Sample-test 2 | a | 393 | 393 | 396 |
b | 399 | 402 | ||
c | 403 | 403 | ||
Sample-test 3 | a | 365 | 345 | 387 |
b | 367 | 382 | ||
c | 372 | 408 | ||
Sample-test 4 | a | 402 | 402 | 410 |
b | 405 | 415 | ||
c | 439 | 412 | ||
Sample-test 5 | a | 333 | 333 | 332 |
b | 331 | 328 | ||
c | 327 | 341 |
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Sun, Y.; Luo, Y.; Chai, X.; Zhang, P.; Zhang, Q.; Xu, L.; Wei, L. Double-Threshold Segmentation of Panicle and Clustering Adaptive Density Estimation for Mature Rice Plants Based on 3D Point Cloud. Electronics 2021, 10, 872. https://doi.org/10.3390/electronics10070872
Sun Y, Luo Y, Chai X, Zhang P, Zhang Q, Xu L, Wei L. Double-Threshold Segmentation of Panicle and Clustering Adaptive Density Estimation for Mature Rice Plants Based on 3D Point Cloud. Electronics. 2021; 10(7):872. https://doi.org/10.3390/electronics10070872
Chicago/Turabian StyleSun, Yixin, Yusen Luo, Xiaoyu Chai, Pengpeng Zhang, Qian Zhang, Lizhang Xu, and Lele Wei. 2021. "Double-Threshold Segmentation of Panicle and Clustering Adaptive Density Estimation for Mature Rice Plants Based on 3D Point Cloud" Electronics 10, no. 7: 872. https://doi.org/10.3390/electronics10070872
APA StyleSun, Y., Luo, Y., Chai, X., Zhang, P., Zhang, Q., Xu, L., & Wei, L. (2021). Double-Threshold Segmentation of Panicle and Clustering Adaptive Density Estimation for Mature Rice Plants Based on 3D Point Cloud. Electronics, 10(7), 872. https://doi.org/10.3390/electronics10070872