Researching | Non-contact wave height measurement method based on laser incident spot recognition

Optics and Precision Engineering, Volume. 29, Issue 9, 2065(2021)

Non-contact wave height measurement method based on laser incident spot recognition

Jun WU1...2,*, Yue-jie SHU3, Shi-bao CAO1,2, and Yu-hang QIU12 |Show fewer author(s)

Author Affiliations

¹Chongqing Southwest Research Institute for Water Transport Engineering， Chongqing Jiaotong University， Chongqing40006， China

²Key Laboratory of Inland Waterway Regulation Engineering Ministry of Transport， Chongqing Jiaotong University， Chongqing400074， China

³Chongqing Xike Waterway Engineering Consulting Center， Chongqing400016， China

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Abstract Get PDF(in Chinese)

Figures&Tables (15)

References (15)

Paper Information

Figures & Tables(15)

Fig. 1. Wave height recording curve

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Fig. 2. Measuring principle of wave height based on laser spot

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Fig. 3. Imaging geometry

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Fig. 4. Binary image of laser entry characteristics

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Fig. 5. Binary image template

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Fig. 6. Search process

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Fig. 7. Calculation result of similarity measure

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Fig. 8. Experimental devices for non-contact wave height measurement

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Fig. 9. Calibration devices for wave height measurement

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Fig. 10. Calibration curve

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Fig. 11. Wave simulator

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Fig. 12. Comparison of wave simulation and measurement results

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Table 1. [in Chinese]

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Table 1. [in Chinese]

目的：搜索图像S中的激光光斑的坐标

输入：每帧图像f、模板A

While（f）

#f为帧编号

提取每帧单色图像，得到灰度图像

采用阈值分割算法，对灰度图像进行二值化，得到二值化图像

For $θ = 0 ° : 1 ° : 20 °$

计算旋转矩阵： $M = [\begin{matrix} c o s θ & - s i n θ \\ s i n θ & c o s θ \end{matrix}]$

For i=SX：1：SX+n

For j=SY：1：SY+m

#（SX，SY）：左上角像素坐标

#m， n：模板像素尺寸

计算相似度函数： $E (θ, i, j)$

End

End

End

计算最小测度函数值 $m i n E (θ, i, j)$

$θ_{0} = \{θ | m i n (m i n E (θ, i, j))\}$

旋转角度为 $θ_{0}$ 时的相似度测度函数构成二维强度图，该图谷底坐标即为匹配的搜索子图位置： $(i_{0}, j_{0}) = \{(i, j) | m i n E (θ_{0}, i, j)\}$

激光光斑图像坐标： $(u, v) = (i_{0} + \frac{n}{2}, j_{0} + \frac{m}{2})$

更新搜索区域，新的ROI区域中心坐标为 $(i_{0}, j_{0})$ ，长宽分别为2n和2m

End

输出：每帧图像激光光斑的图像坐标系列

(u_{l}, v_{l})

， l=0，1，….

Table 1. Parameters of non-contact wave height measurement experimental devices

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Table 1. Parameters of non-contact wave height measurement experimental devices

参数类型	参数	指标
结构参数	H	50 cm
	H₀	10 cm
	$α$	45°
摄像机参数	像素	1 920×1 080
	水平视场角ω	89°
	帧率	30 frame/s
半导体激光器参数	功率	100 mW
	波长	650 nm
	光斑模式	点状
	光斑直径	3 mm（1 m距离）

Table 2. Calibration result of wave height sensor

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Table 2. Calibration result of wave height sensor

光斑像素坐标		水位测针测量值H/mm	像素距离	实际位置 /mm	标定公式计算值 /mm	误差 /mm
u	v	水位测针测量值H/mm	像素距离	实际位置 /mm	标定公式计算值 /mm	误差 /mm
479	732	0	1 015.57	360	359.54	0.46
552	730	10	942.54	350	350.43	-0.43
617	728	20	877.51	340	340.30	-0.30
675	726	30	819.48	330	330.06	-0.06
726	724	40	768.44	320	320.31	-0.31
778	722	50	716.40	310	309.74	0.26
826	720	60	668.36	300	299.44	0.56
870	720	70	624.39	290	289.54	0.46
910	718	80	584.34	280	280.07	-0.07
952	716	90	542.30	270	269.60	0.40
988	714	100	506.25	260	260.11	-0.11
1 024	712	110	470.21	250	250.05	-0.05
1 058	712	120	436.22	240	239.96	0.04
1 088	712	130	406.24	230	230.49	-0.49
1 119	712	140	375.26	220	220.07	-0.07
1 146	710	150	348.21	210	210.37	-0.37
1 172	710	160	322.22	200	200.47	-0.47
1 197	708	170	297.17	190	190.32	-0.32
1 221	708	180	273.18	180	179.98	0.02
1 243	706	190	251.13	170	169.91	0.09
1 264	706	200	230.14	160	159.77	0.23
1 284	706	210	210.15	150	149.57	0.43
1 302	704	220	192.09	140	139.88	0.12
1 320	706	230	174.18	130	129.78	0.22
1 336	704	240	158.11	120	120.29	-0.29
1 353	704	250	141.13	110	109.79	0.21
1 368	704	260	126.14	100	100.11	-0.11
1 383	702	270	111.07	90	89.96	0.04
1 398	704	280	96.19	80	79.51	0.49
1 411	702	290	83.10	70	69.96	0.04
1 424	702	300	70.11	60	60.13	-0.13
1 437	702	310	57.14	50	49.95	0.05
1 449	700	320	45.04	40	40.12	-0.12
1 461	702	330	33.24	30	30.21	-0.21
1 473	700	340	21.10	20	19.66	0.34
1 484	700	350	10.20	10	9.89	0.11
1 494	698	360	0.00	0	以该点为零点

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Jun WU, Yue-jie SHU, Shi-bao CAO, Yu-hang QIU. Non-contact wave height measurement method based on laser incident spot recognition[J]. Optics and Precision Engineering, 2021, 29(9): 2065

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Paper Information

Category: Modern Applied Optics

Received: Dec. 31, 2020

Accepted: --

Published Online: Nov. 22, 2021

The Author Email: WU Jun (195575462@qq.com)

DOI:10.37188/OPE.20212909.2065

Topics

laser devices and laser physics

Lasers and Laser Optics

laser manufacturing

Instrumentation, Measurement and Metrology