scholarly journals Optimization of the stereo system calibration parameters for photogrammetric measurements in the conditions of field experiments

2021 ◽  
Vol 2127 (1) ◽  
pp. 012029
Author(s):  
V V Pinchukov ◽  
E V Shmatko ◽  
A D Bogachev ◽  
A Yu Poroykov
Keyword(s):  
Field Experiments ◽  
Three Dimensional ◽  
Video Camera ◽  
Surface Shape ◽  
Optical Methods ◽  
System Calibration ◽  
Reprojection Error ◽  
Photogrammetric Method ◽  
Vibration Loads ◽  
Calibration Parameters

Abstract Optical methods for deformation diagnostics and surface shape measurement are often used in scientific research and industry. Most of these methods are based on the triangulation of a set of two-dimensional points from different images corresponding to the three-dimensional points of an object in space. Triangulation is based on the stereo system calibration parameters, which are determined before the experiment. Measurements during conditions with increased vibration loads can lead to a change in the relative position of the cameras of the stereo system (decalibration). This leads to a change in the actual calibration parameters and an increase in the measurement error. This work aims to solve the problem of increasing the measurement accuracy of the photogrammetric method in the case of high vibration loads. For this, it is proposed to use an optimization algorithm for calibration parameters to minimize the reprojection error of three-dimensional points calculated using triangulation. The paper presents the results of a computer simulation of decalibration of a video camera stereo system, an algorithm for optimizing the external parameters of a stereo system, and an assessment of its performance.

scholarly journals Computer and Physical Modeling for Verification of the Stereo System Calibration Parameters Optimization Results

2021 ◽  
Author(s):  
Vladislav Pinchukov ◽  
Ekaterina Shmatko ◽  
Anton Poroykov ◽  
Artem Bogachev
Keyword(s):  
Physical Modeling ◽  
Video Camera ◽  
Parameters Optimization ◽  
Surface Shape ◽  
Experimental Investigations ◽  
System Calibration ◽  
Video Cameras ◽  
Close Range ◽  
Optimizing Algorithm ◽  
Calibration Parameters

Close-range photogrammetry is widely used to measure surface shapes and diagnose deformation. Usually, a stereo system of video cameras is used to register images of the measured object from several different angles. The surface shape is determined by triangulating a set of 2D points from these images. Triangulation uses the stereo system calibration parameters, which are determined before the experiment. Measurements during conditions with increased vibration loads can lead to a change in the relative position of the cameras of the stereo system (decalibration). This leads to a change in the actual calibration parameters and an increase in the measurement error. The decalibration problem can be solved using multidimensional optimization algorithms. To verify their calculation's results it is proposed to use a computer and physical modeling of decalibration of a video camera stereo system in laboratory conditions. The paper presents the implementation of the optimizing algorithm for the external parameters of a stereo system and the results of its performance during the experimental investigations.

scholarly journals Crosscorrelation image processing for surface shape reconstruction using fiducial markers

2021 ◽  
Vol 2127 (1) ◽  
pp. 012030
Author(s):  
E V Shmatko ◽  
V V Pinchukov ◽  
A D Bogachev ◽  
A Yu Poroykov
Keyword(s):  
Correlation Function ◽  
Cross Correlation ◽  
Three Dimensional ◽  
Shape Reconstruction ◽  
Surface Shape ◽  
Optical Methods ◽  
Shape Measurement ◽  
Fiducial Markers ◽  
Correlation Processing ◽  
Function Calculation

Abstract Optical methods for deformations diagnostic and surface shape measurement are widely used in scientific research and industry. Most of these methods are based on triangulating a set of two-dimensional points in the images appropriate to the same three-dimensional points of the object in space. Various algorithms to search such points are applied. The possibility of using cross-correlation processing of digital images to search these points is considered in the work. Algorithms based on the correlation function calculation are widely employed in such a popular flow diagnostic method as PIV. The cameras of a stereo system for surface shape measurement can be widely spaced, and the tilt angles relative to the surface can differ significantly. This leads to the fact that the images taken from the cameras cannot be directly processed by the correlation function because it is not invariant to rotation. To solve this problem, fiducial markers are used to find an initial estimate of displacement of the images relative to each other. This approach makes it possible to successfully apply correlation processing for stereo system images with a large stereo base.

scholarly journals The Numerical Analysis of the Flow on the Smooth and Nonsmooth Boundaries by IBEM/DBIEM

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Gang Xu ◽  
Guangwei Zhao ◽  
Jing Chen ◽  
Shuqi Wang ◽  
Weichao Shi
Keyword(s):  
Boundary Value ◽  
Three Dimensional ◽  
Boundary Surface ◽  
Tangential Velocity ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Surface Shape ◽  
Normal Vector ◽  
Computational Domain ◽  
Nonsmooth Boundary

The value of the tangential velocity on the Boundary Value Problem (BVP) is inaccurate when comparing the results with analytical solutions by Indirect Boundary Element Method (IBEM), especially at the intersection region where the normal vector is changing rapidly (named nonsmooth boundary). In this study, the singularity of the BVP, which is directly arranged in the center of the surface of the fluid computing domain, is moved outside the computational domain by using the Desingularized Boundary Integral Equation Method (DBIEM). In order to analyze the accuracy of the IBEM/DBIEM and validate the above-mentioned problem, three-dimensional uniform flow over a sphere has been presented. The convergent study of the presented model has been investigated, including desingularized distance in the DBIEM. Then, the numerical results were compared with the analytical solution. It was found that the accuracy of velocity distribution in the flow field has been greatly improved at the intersection region, which has suddenly changed the boundary surface shape of the fluid domain. The conclusions can guide the study on the flow over nonsmooth boundaries by using boundary value method.

Study on Magnetic Barrel Machine Equipped with Three-Dimensional Arrangement of Magnets

2007 ◽  
Vol 329 ◽  
pp. 761-766 ◽  
Author(s):  
Y. Zhang ◽  
Masato Yoshioka ◽  
Shin-Ichiro Hira
Keyword(s):  
High Speed ◽  
Permanent Magnets ◽  
Three Dimensional ◽  
Video Camera ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
The Media ◽  
Set Up

At present, a commercially available magnetic barrel machine equipped with permanent magnets has some faults arising from constructional reason. That is, grinding or finishing ability is different from place to place in the machining region, resulting in the limitation on the region we can use in the container of workpieces. Therefore, in this research, authors made the new magnetic barrel machine equipped with three dimensional (3D) magnet arrangement to overcome these faults. The grinding ability of the new 3D magnetic barrel machine converted was experimentally examined, and compared with that of the traditional magnetic barrel machine. As a result, it was shown that we can use much broader region in the new 3D machine. It was also shown that the grinding ability became higher. The distribution of barrel media in action was recorded by means of a high speed video camera. It was clarified that the media rose up higher and were distributed more uniformly in the container by the effect of the magnet block newly set up. It was supposed that this must be the reason for the above-mentioned improvement of grinding ability.

Positron Emission Tomography (PET) for Flow Measurement

2011 ◽  
Vol 301-303 ◽  
pp. 1316-1321 ◽  
Author(s):  
Arthur E. Ruggles ◽  
Bi Yao Zhang ◽  
Spero M. Peters
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Three Dimensional ◽  
Bulk Water ◽  
Emission Tomography ◽  
Optical Methods ◽  
Imaging Method ◽  
Analysis And Design ◽  
Pet Tracer ◽  
Positron Emission

Positron Emission Tomography (PET) produces a three dimensional spatial distribution of positron-electron annihilations within an image volume. Various positron emitters are available for use in aqueous, organic and liquid metal flows. Preliminary experiments at the University of Tennessee at Knoxville (UTK) injected small flows of PET tracer into a bulk water flow in a four rod bundle. The trajectory and diffusion of the tracer in the bulk flow were then mapped using a PET scanner. A spatial resolution of 1.4 mm is achieved with current preclinical Micro-PET imaging equipment resulting in 200 MB 3D activity fields. A time resolved 3-D spatial activity profile was also measured. The PET imaging method is especially well suited to complex geometries where traditional optical methods such as LDV and PIV are difficult to apply. PET methods are uniquely useful for imaging in opaque fluids, opaque pressure boundaries, and multiphase studies. Several commercial and shareware Computational Fluid Dynamics (CFD) codes are currently used for science and engineering analysis and design. These codes produce detailed three dimensional flow predictions. The models produced by these codes are often difficult to validate. The development of this experimental technique offers a modality for the comparison of CFD outcomes with experimental data. Developed data sets from PET can be used in verification and validation exercises of simulation outcomes.

scholarly journals A Novel Approach for Operating Speed Continuous Predication Based on Alignment Space Comprehensive Index

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Ying Yan ◽  
Gengping Li ◽  
Jinjun Tang ◽  
Zhongyin Guo
Keyword(s):  
Field Experiments ◽  
Prediction Models ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Driving Safety ◽  
Operating Speed ◽  
Passenger Cars ◽  
Comprehensive Index ◽  
Novel Approach ◽  
Lane Width

Operating speed is a critical indicator for road alignment consistency design and safety evaluation. Although extensive studies have been conducted on operating speed prediction, few models can finish practical continuous prediction at each point along alignment on multilane highways. This study proposes a novel method to estimate the operating speed for multilane highways in China from the aspect of the three-dimensional alignment combination. Operating speed data collected in field experiments on 304 different alignment combination sections are detected by means of Global Positioning System. First, the alignment comprehensive index (ACI) is designed and introduced to describe the function accounting for alignment continuity and driving safety. The variables used in ACI include horizontal curve radius, change rate of curvature, deflection angle of curve, grade, and lane width. Second, the influence range of front and rear alignment on speed is determined on the basis of drivers’ fixation range and dynamical properties of vehicles. Furthermore, a prediction model based on exponential relationships between road alignment and speeds is designed to predict the speed of passenger cars and trucks. Finally, three common criteria are utilized to evaluate the effectiveness of the prediction models. The results indicate that the prediction models outperform the other two operating speed models for their higher prediction accuracy.

scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

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