scholarly journals Adaptive Structured Light with Scatter Correction for High-Precision Underwater 3D Measurements

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1043 ◽  
Author(s):  
Petter Risholm ◽  
Trine Kirkhus ◽  
Jens Thielemann ◽  
Jostein Thorstensen
Keyword(s):  
High Precision ◽  
Structured Light ◽  
Scatter Correction ◽  
Gray Code ◽  
Forward Scatter ◽  
Phase Stepping ◽  
Accuracy And Precision ◽  
Phase Unwrap ◽  
Phase Estimate ◽  
Frequency Phase

High-precision underwater 3D cameras are required to automate many of the traditional subsea inspection, maintenance and repair (IMR) operations. In this paper we introduce a novel multi-frequency phase stepping (structured light) method for high-precision 3D estimation even in turbid water. We introduce an adaptive phase-unwrapping procedure which uses the phase-uncertainty to determine the highest frequency that can be reliably unwrapped. Light scattering adversely affects the phase estimate. We propose to remove the effect of forward scatter with an unsharp filter and a model-based method to remove the backscatter effect. Tests in varying turbidity show that the scatter correction removes the adverse effect of scatter on the phase estimates. The adaptive frequency unwrapping with scatter correction results in images with higher accuracy and precision and less phase unwrap errors than the Gray-Code Phase Stepping (GCPS) approach.

scholarly journals A High-Precision Registration Technology Based on Bundle Adjustment in Structured Light Scanning System

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jianying Yuan ◽  
Qiong Wang ◽  
Xiaoliang Jiang ◽  
Bailin Li
Keyword(s):  
High Precision ◽  
Large Scale ◽  
Structured Light ◽  
Bundle Adjustment ◽  
Scanning System ◽  
Control Points ◽  
Registration Method ◽  
Global Control ◽  
3D Data ◽  
Structured Light Scanning

The multiview 3D data registration precision will decrease with the increasing number of registrations when measuring a large scale object using structured light scanning. In this paper, we propose a high-precision registration method based on multiple view geometry theory in order to solve this problem. First, a multiview network is constructed during the scanning process. The bundle adjustment method from digital close range photogrammetry is used to optimize the multiview network to obtain high-precision global control points. After that, the 3D data under each local coordinate of each scan are registered with the global control points. The method overcomes the error accumulation in the traditional registration process and reduces the time consumption of the following 3D data global optimization. The multiview 3D scan registration precision and efficiency are increased. Experiments verify the effectiveness of the proposed algorithm.

scholarly journals High-Precision In Situ 87Sr/86Sr Analyses through Microsampling on Solid Samples: Applications to Earth and Life Sciences

2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Sara Di Salvo ◽  
Eleonora Braschi ◽  
Martina Casalini ◽  
Sara Marchionni ◽  
Teresa Adani ◽  
...  
Keyword(s):  
High Precision ◽  
Life Sciences ◽  
Magma Ascent ◽  
Forensic Sciences ◽  
Sr Isotope ◽  
High Performing ◽  
Accuracy And Precision ◽  
Wide Range ◽  
Significant Case

An analytical protocol for high-precision, in situ microscale isotopic investigations is presented here, which combines the use of a high-performing mechanical microsampling device and high-precision TIMS measurements on micro-Sr samples, allowing for excellent results both in accuracy and precision. The present paper is a detailed methodological description of the whole analytical procedure from sampling to elemental purification and Sr-isotope measurements. The method offers the potential to attain isotope data at the microscale on a wide range of solid materials with the use of minimally invasive sampling. In addition, we present three significant case studies for geological and life sciences, as examples of the various applications of microscale 87Sr/86Sr isotope ratios, concerning (i) the pre-eruptive mechanisms triggering recent eruptions at Nisyros volcano (Greece), (ii) the dynamics involved with the initial magma ascent during Eyjafjallajökull volcano’s (Iceland) 2010 eruption, which are usually related to the precursory signals of the eruption, and (iii) the environmental context of a MIS 3 cave bear, Ursus spelaeus. The studied cases show the robustness of the methods, which can be also be applied in other areas, such as cultural heritage, archaeology, petrology, and forensic sciences.

scholarly journals A Structured Light RGB-D Camera System for Accurate Depth Measurement

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Van Luan Tran ◽  
Huei-Yung Lin
Keyword(s):  
Template Matching ◽  
Structured Light ◽  
Gray Code ◽  
Object Surface ◽  
Camera System ◽  
3D Vision ◽  
Depth Measurement ◽  
Sensing System ◽  
Extrinsic Parameters ◽  
Intrinsic And Extrinsic Parameters

The ability to reliably measure the depth of the object surface is very important in a range of high-value industries. With the development of 3D vision techniques, RGB-D cameras have been widely used to perform the 6D pose estimation of target objects for a robotic manipulator. Many applications require accurate shape measurements of the objects for 3D template matching. In this work, we develop an RGB-D camera based on the structured light technique with gray-code coding. The intrinsic and extrinsic parameters of the camera system are determined by a calibration process. 3D reconstruction of the object surface is based on the ray triangulation principle. We construct an RGB-D sensing system with an industrial camera and a digital light projector. In the experiments, real-world objects are used to test the feasibility of the proposed technique. The evaluation carried out using planar objects has demonstrated the accuracy of our RGB-D depth measurement system.

scholarly journals 3D Measurement Technology by Structured Light Using Stripe-Edge-Based Gray Code

2006 ◽  
Vol 48 ◽  
pp. 537-541 ◽  
Author(s):  
H B Wu ◽  
Y Chen ◽  
M Y Wu ◽  
C R Guan ◽  
X Y Yu
Keyword(s):  
Structured Light ◽  
Gray Code ◽  
Measurement Technology ◽  
3D Measurement ◽  
Edge Based

Research on Calibration Method of Linear Structured Light Vision Measurement System

2014 ◽  
Vol 644-650 ◽  
pp. 1234-1239
Author(s):  
Tao He ◽  
Yu Lang Xie ◽  
Cai Sheng Zhu ◽  
Jiu Yin Chen
Keyword(s):  
High Precision ◽  
Measurement System ◽  
Structured Light ◽  
Target Position ◽  
Calibration Method ◽  
Measurement Model ◽  
Sensor Calibration ◽  
Vision Measurement ◽  
Set Up ◽  
Structured Light Vision

This template explains and demonstrates how to design a measurement system based on the size of the linear structured light vision, the system could works at realized the high precision and fast measurement of the size of mechanical parts, and accurate calibration of the system. First of all, this paper set up the experimental platform based on linear structured light vision measurement. Secondly, this paper established a system of measurement model, and puts forward a new method of calibration of structured light sensor and set up the mathematical model of sensor calibration. This calibration method only need to use some gage blocks of high precision as the target, the target position need not have a strict requirements, and the solving process will be more convenient, much easier to field use and maintenance. Finally, measuring accuracy on the system by gage blocks with high precision is verified, the experiment shows that measurement accuracy within 0.050 mmin the depth of 0-80 - mm range. This system can satisfy the demands of precision testing of most industrial parts .with its simple calibration process and high precision, it is suitable for the structured light vision calibration.

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