Microlens Array-Based Spatial Angle Encoding for High-Precision Visual Pose Measurement

Fig. 2. Micrographics array and dynamic display effect. (a) Micrographics array; (b)(c) display patterns at different shooting angles (after perspective transformation)

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Fig. 3. Weighted estimation of x-axis and y-axis rotation angles

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Fig. 4. Experimental scene. (a) Experimental setup; (b) camera; (c) rotator and microlens array fiducial marker; (d) display of microlens array fiducial marker

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Fig. 5. Schematic diagram of viewpoint variation range in angular vector space

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Fig. 6. Display patterns at different shooting angles (after perspective transformation). (a) $ψ = 0.5 °, θ = 1.5 °$ ; (b) $ψ = 0.5 °, θ = 2.0 °$ ; (c) $ψ = 0 °, θ = 1.5 °$ ; (d) $ψ = 1.0 °, θ = 1.5 °$

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Fig. 7. Pose measurement results. (a) x-axis rotation angle error; (b) y-axis rotation angle error; (c) z-axis rotation angle error; (d) estimation result of translation in x direction; (e) estimation result of translation in y direction; (f) estimation result of translation in z direction

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Table 1. Comparison of average measurement error of rotation angle by different methods
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Table 1. Comparison of average measurement error of rotation angle by different methods
Method x axis y axis
MLA+ 0.0659 0.0787
MLA 0.1227 0.1284
P4P 2.3061 0.6373

Table 2. Comparison of average measurement error of rotation angle by OSTU method and maximum information entropy method
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Table 2. Comparison of average measurement error of rotation angle by OSTU method and maximum information entropy method
Method x axis y axis
OTSU 0.0659 0.0787
Maximum information entropy 0.1409 0.3985

Table 3. Comparison of failure number of rotation angle measurement by two gray threshold segmentation methods
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Table 3. Comparison of failure number of rotation angle measurement by two gray threshold segmentation methods
Method Condition x axis y axis
OTSU Unweighted 0 0
Weighted 0 0
Maximum information entropy Unweighted 2 21
Weighted 1 16

Table 4. Average measurement error of rotation angle under different threshold number
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Table 4. Average measurement error of rotation angle under different threshold number
Threshold number x axis y axis
1 0.0659 0.0787
2 0.0545 0.0856
3 0.0733 0.0860
4 0.0707 0.0838

Table 5. Comparison of average measurement error of rotation angle by dense encoding method and linear interpolation method
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Table 5. Comparison of average measurement error of rotation angle by dense encoding method and linear interpolation method
Method x axis y axis
Dense encoding（ours） 0.0659 0.0787
Linear interpolation 0.4880 0.4690

Table 6. Average Hamming distance at different angle intervals
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Table 6. Average Hamming distance at different angle intervals
Angle interval x axis y axis
0.1 3.58 3.10
0.2 7.04 6.10
0.3 10.51 9.08
0.4 13.92 11.98
0.5 17.43 14.83

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Liangliang Mo, Jieji Ren, Mingjun Ren. Microlens Array-Based Spatial Angle Encoding for High-Precision Visual Pose Measurement[J]. Acta Optica Sinica, 2022, 42(16): 1612002

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Paper Information

Category: Instrumentation, Measurement and Metrology

Received: Jan. 25, 2022

Accepted: Mar. 21, 2022

Published Online: Aug. 4, 2022

The Author Email: Ren Mingjun (renmj@sjtu.edu.cn)

DOI:10.3788/AOS202242.1612002

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Comparison of average measurement error of rotation angle by different methods

Table 1. Comparison of average measurement error of rotation angle by different methods

Table 2. Comparison of average measurement error of rotation angle by OSTU method and maximum information entropy method

Table 2. Comparison of average measurement error of rotation angle by OSTU method and maximum information entropy method

Table 3. Comparison of failure number of rotation angle measurement by two gray threshold segmentation methods

Table 3. Comparison of failure number of rotation angle measurement by two gray threshold segmentation methods

Table 4. Average measurement error of rotation angle under different threshold number

Table 4. Average measurement error of rotation angle under different threshold number

Table 5. Comparison of average measurement error of rotation angle by dense encoding method and linear interpolation method

Table 5. Comparison of average measurement error of rotation angle by dense encoding method and linear interpolation method

Table 6. Average Hamming distance at different angle intervals

Table 6. Average Hamming distance at different angle intervals