Calibration Method for Line-Structured Light

Ruifeng Zhang; Ziyun Shu; Ganglei Nan

doi:10.3788/LOP56.221101

Journals >Laser & Optoelectronics Progress >Volume 56 >Issue 22 >Page 221101 > Article

Laser & Optoelectronics Progress
Vol. 56, Issue 22, 221101 (2019)

Calibration Method for Line-Structured Light

Ruifeng Zhang, Ziyun Shu^*, and Ganglei Nan

Author Affiliations

School of Microelectronics, Tianjin University, Tianjin 300072, China

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DOI: 10.3788/LOP56.221101 Cite this Article Set citation alerts

Ruifeng Zhang, Ziyun Shu, Ganglei Nan. Calibration Method for Line-Structured Light[J]. Laser & Optoelectronics Progress, 2019, 56(22): 221101 Copy Citation Text

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Fig. 1. Camera perspective projection model

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Fig. 2. Diagram of line-structured light sensor

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Fig. 3. Flow chart of calibration for line-structured light

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Fig. 4. Images taken by light plane calibration

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Fig. 5. Picture of engine cylinder head

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Fig. 6. Three-dimensional point clouds after encapsulation. (a) Top view; (b) front view

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Method of calibration	Number of feature points	Equation of light plane
Invariance of cross-ratio	8	0.999438X-0.0333133Y-0.00363374Z+68.6157=0
Our method	All feature points on the light stripe	0.999414X-0.0340966Y+0.00295146Z+65.1016=0

Table 1. Calibration results of two calibration methods

Method ofcalibration	Number offeature points	Sum of thedistances /mm
Invariance ofcross-ratio	All feature points	32.74879
Out method	All feature points	31.73931

Table 2. Evaluation results of calibration results of two calibration methods

Gascavity	X direction				Y direction				Z direction
Gascavity	Stand-ard /mm	Meas-ured /mm	Absoluteerror /mm	Relativeerror /%	Stand-ard /mm	Meas-ured /mm	Absoluteerror /mm	Relativeerror /%	Stand-ard /mm	Meas-ured /mm	Absoluteerror /mm	Relativeerror /%
A₁	261.12	261.21	0.09	0.034	47.30	47.21	0.09	0.190	/	/	/	/
B₁	261.12	261.09	0.03	0.011	0.00	0.10	0.10	/	/	/	/	/
C₁	274.82	274.90	0.08	0.029	131.65	131.69	0.04	0.030	52.30	52.64	0.34	0.650
A₂	130.56	130.50	0.06	0.045	47.30	47.25	0.05	0.105	/	/	/	/
B₂	130.56	130.63	0.07	0.053	0.00	0.09	0.09	/	/	/	/	/
C₂	144.26	144.35	0.09	0.062	131.65	131.60	0.05	0.037	52.30	52.56	0.26	0.497
A₃	0	0.08	0.08	/	47.30	47.40	0.10	0.211	/	/	/	/
B₃	0	0	0	/	0	0.09	0.09	/	/	/	/	/
C₃	13.70	13.75	0.05	0.360	131.65	131.70	0.05	0.037	52.30	52.65	0.35	0.669
A₄	130.56	130.62	0.06	0.045	47.30	47.40	0.10	0.211	/	/	/	/
B₄	130.56	130.48	0.08	0.061	0.00	0.06	0.06	/	/	/	/	/
C₄	116.86	116.96	0.10	0.085	131.65	131.60	0.05	0.037	52.30	52.45	0.15	0.287

Table 3. Measurement results of cylinder head based on proposed method

Gascavity	X direction				Y direction				Z direction
Gascavity	Stand-ard /mm	Meas-ured /mm	Absoluteerror /mm	Relativeerror /%	Stand-ard /mm	Meas-ured /mm	Absoluteerror /mm	Relativeerror /%	Stand-ard /mm	Meas-ured /mm	Absoluteerror /mm	Relativeerror /%
A₁	261.12	261.21	0.09	0.034	47.30	47.21	0.09	0.190	/	/	/	/
B₁	261.12	261.09	0.03	0.011	0.00	0.11	0.11	/	/	/	/	/
C₁	274.82	274.90	0.08	0.029	131.65	131.97	0.32	0.243	52.30	52.99	0.69	1.319
A₂	130.56	131.20	0.64	0.490	47.30	47.16	0.14	0.295	/	/	/	/
B₂	130.56	130.16	0.40	0.306	0.00	0.38	0.38	/	/	/	/	/
C₂	144.26	144.88	0.62	0.429	131.65	131.97	0.32	0.243	52.30	53.21	0.91	1.739
A₃	0	-0.08	0.08	/	47.30	47.45	0.15	0.317	/	/	/	/
B₃	0	0	0	/	0	0	0	/	/	/	/	/
C₃	13.70	13.75	0.05	0.360	131.65	131.97	0.32	0.243	52.30	52.64	0.34	0.650
A₄	130.56	130.33	0.23	0.176	47.30	46.93	0.37	0.782	/	/	/	/
B₄	130.56	130.38	0.18	0.137	0.00	0.15	0.15	/	/	/	/	/
C₄	116.86	117.22	0.36	0.308	131.65	131.97	0.32	0.243	52.30	52.46	0.16	0.305

Table 4. Measurement results of cylinder head obtained by cross ratio invariance based calibration method

Ruifeng Zhang, Ziyun Shu, Ganglei Nan. Calibration Method for Line-Structured Light[J]. Laser & Optoelectronics Progress, 2019, 56(22): 221101

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