Panoramic Display System Geometric Calibration Method Based on Fisheye Camera

Affected by the vibrations and thermal shocks during launch and the orbit penetration process, the geometric positioning model of the remote sensing cameras measured on the ground will generate a displacement, affecting the geometric accuracy of imagery and requiring recalibration. Conventional methods adopt the ground control points (GCPs) or stars as references for on-orbit geometric calibration. However, inescapable cloud coverage and discontented extraction algorithms make it extremely difficult to collect sufficient high-precision GCPs for modifying the misalignment of the camera, especially for geostationary satellites. Additionally, the number of the observed stars is very likely to be inadequate for calibrating the relative installations of the camera. In terms of the problems above, we propose a novel on-orbit geometric calibration method using the relative motion of stars for geostationary cameras. First, a geometric calibration model is constructed based on the optical system structure. Then, we analyze the relative motion transformation of the observed stars. The stellar trajectory and the auxiliary ephemeris are used to obtain the corresponding object vector for correcting the associated calibration parameters iteratively. Experimental results evaluated on the data of a geostationary experiment satellite demonstrate that the positioning errors corrected by this proposed method can be within ±2.35 pixels. This approach is able to effectively calibrate the camera and improve the positioning accuracy, which avoids the influence of cloud cover and overcomes the great dependence on the number of the observed stars.

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A Novel Geometric Calibration Method for Active Stereovision System

10.1109/case49439.2021.9551530 ◽

2021 ◽

Author(s):

Jierui Liu ◽

Xilong Liu ◽

Zhiqiang Cao ◽

Zhonghui Li ◽

Junzhi Yu

Keyword(s):

Calibration Method ◽

Geometric Calibration

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Geometric Calibration Method of Side-Scatter Lidar Based on Charge-Coupled Device

ACTA PHOTONICA SINICA ◽

10.3788/gzxb20154402.0201002 ◽

2015 ◽

Vol 44 (2) ◽

pp. 201002

Author(s):

麻晓敏 MA Xiao-min ◽

史博 SHI Bo ◽

单会会 SHAN Hui-hui ◽

赵素贵 ZHAO Su-gui ◽

陶宗明 TAO Zong-ming

Keyword(s):

Calibration Method ◽

Charge Coupled Device ◽

Geometric Calibration

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A Geometric Calibration Method of Hydrophone Array Based on Maximum Likelihood Estimation with Sources in Near Field

Journal of Marine Science and Engineering ◽

10.3390/jmse8090678 ◽

2020 ◽

Vol 8 (9) ◽

pp. 678

Author(s):

Nan Zou ◽

Zhenqi Jia ◽

Jin Fu ◽

Jia Feng ◽

Mengqi Liu

Keyword(s):

Maximum Likelihood ◽

Maximum Likelihood Estimation ◽

Signal To Noise Ratio ◽

Near Field ◽

Likelihood Estimation ◽

Calibration Method ◽

Optimization Method ◽

High Signal ◽

Geometric Calibration ◽

Environment Experiment

Considering the requirement of the near-field calibration under strong underwater multipath condition, a high-precision geometric calibration method based on maximum likelihood estimation is proposed. It can be used as both auxiliary-calibration and self-calibration. According to the near-field geometry error model, the objective function of nonlinear optimization problem is constructed by using the unconditional maximum likelihood estimator. The influence of multipath on geometric calibration is studied. The strong reflections are considered as the coherent sources, and the compensation strategy for auxiliary-calibration is realized. The optimization method (differential evolution, DE) is used to solve the geometry errors and sources’ position. The method in this paper is compared with the eigenvector method. The simulation results show that the method in this paper is more accurate than the eigenvector method especially under high signal-to-noise ratio (SNR) and multipath environment. Experiment results further verify the effectiveness.

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Combining Head-Mounted and Projector-Based Displays for Surgical Training

Presence Teleoperators & Virtual Environments ◽

10.1162/1054746041382375 ◽

2004 ◽

Vol 13 (2) ◽

pp. 128-145 ◽

Cited By ~ 9

Author(s):

Adrian Ilie ◽

Kok-Lim Low ◽

Greg Welch ◽

Anselmo Lastra ◽

Henry Fuchs ◽

...

Keyword(s):

Virtual Reality ◽

Surgical Training ◽

Human Subject ◽

Visual Awareness ◽

Display System ◽

Geometric Calibration ◽

Calibration Process ◽

Surrounding Environment ◽

Human Subject Experiment ◽

Subject Experiment

We introduce and present preliminary results for a hybrid display system combining head-mounted and projector-based displays. Our work is motivated by a surgical training application where it is necessary to simultaneously provide both a highfidelity view of a central close-up task (the surgery) and visual awareness of objects and events in the surrounding environment. In this article, we motivate the use of a hybrid display system, discuss previous work, describe a prototype along with methods for geometric calibration, and present results from a controlled human subject experiment. This article is an invited resubmission of work presented at IEEE Virtual Reality 2003. The article has been updated and expanded to include (among other things) additional related work and more details about the calibration process.

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Field Geometric Calibration Method for Line Structured Light Sensor Using Single Circular Target

Scientific Programming ◽

10.1155/2017/1526706 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Tianfei Chen ◽

Lijun Sun ◽

Qiuwen Zhang ◽

Xiang Wu ◽

Defeng Wu

Keyword(s):

Structured Light ◽

Linear Equations ◽

Calibration Method ◽

Experimental Result ◽

Normal Vector ◽

Geometric Calibration ◽

Light Plane ◽

Light Sensor ◽

Fitting Method ◽

Circular Target

To achieve fast calibration of line structured light sensor, a geometric calibration approach based on single circular calibration target is proposed. The proposed method uses the circular points to establish linear equations, and according to the angle constraint, the camera intrinsic parameters can be calculated through optimization. Then, the light plane calibration is accomplished in two steps. Firstly, when the vanishing lines of target plane at various postures are obtained, the intersections between vanishing lines and laser stripe can be computed, and the normal vector of light plane can be calibrated via line fitting method using intersection points. After that, the distance from the origin of camera coordinate system to the light plane can be derived based on the model of perspective-three-point. The actual experimental result shows that this calibration method has high accuracy, its average measuring accuracy is 0.0451 mm, and relative error is 0.2314%. In addition, the entire calibration process has no complex operations. It is simple, convenient, and suitable for calibration on sites.

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Approach for Zero Defect Manufacturing: Geometric Calibration of Five-Axis Machine Tools for Blisk Manufacturing Process

Volume 6: Ceramics; Controls, Diagnostics, and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2018-77195 ◽

2018 ◽

Author(s):

Tae Hun Lee ◽

Jan Behrens ◽

Sascha Gierlings ◽

Christian Brecher

Keyword(s):

Manufacturing Process ◽

Turbine Blades ◽

Calibration Method ◽

Test Method ◽

Machining Process ◽

Critical Conditions ◽

Geometric Calibration ◽

Measurement Devices ◽

Five Axis ◽

Five Axes

Five-axis machining is a key technology of blisk manufacturing process. Blisks generally require high accuracy due to their high performance and safety-critical conditions. However, recent research show that the design of the blisks and turbine blades are getting more complex and require even higher accuracy. This leads also to the application of wide and rare area of movement axes of the machine. Thus, the machine accuracy has to be assured within the overall machine volume. The geometric accuracy demonstrates the base accuracy of the machine. This paper presents a geometric calibration method optimized for the axes movement area of blisk machining process. The accurate calibration of the five-axis machine tool is challenging and hardly possible due to limited error measurement of standard measurement devices. Some measurement methods enable complete calibration of the machine but with complex, time-consuming process and expensive measurement devices. Also, due to the rare axes travel, there is no standard calibration method for the blisk machining process. The calibration method in this paper is developed based on so called ‘R-test’ method. The machine and the errors are modelled mathematically for the measurement. An adapter is applied for the measurement of maximum axis positions. Automation units are developed for the full machine integration and automation of calibration procedure. With the developed method, the machine is calibrated from 130 μm to 10 μm in maximum measurement time of 90 minutes. The calibration quality is validated at an independent measurement position with continuous movement of the five axes.

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Calibration method applied to a tunable tensor display system

Three-Dimensional Imaging, Visualization, and Display 2019 ◽

10.1117/12.2518865 ◽

2019 ◽

Author(s):

David Carmona-Ballester ◽

Viana Lida Guadalupe-Suárez ◽

Juan Manuel Trujillo-Sevilla ◽

Sergio Bonaque-González ◽

Ricardo Oliva-García ◽

...

Keyword(s):

Calibration Method ◽

Display System

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A Novel Calibration Algorithm for Cable-Driven Parallel Robots with Application to Rehabilitation

Applied Sciences ◽

10.3390/app9112182 ◽

2019 ◽

Vol 9 (11) ◽

pp. 2182 ◽

Cited By ~ 3

Author(s):

Han Yuan ◽

Xianghui You ◽

Yongqing Zhang ◽

Wenjing Zhang ◽

Wenfu Xu

Keyword(s):

Calibration Method ◽

Parallel Robot ◽

Parallel Robots ◽

Human Robot Interaction ◽

Automatic Calibration ◽

Unknown Parameters ◽

Robot Interaction ◽

Geometric Calibration ◽

Rehabilitation Robots ◽

Calibration Algorithm

Cable-driven parallel robots are suitable candidates for rehabilitation due to their intrinsic flexibility and adaptability, especially considering the safety of human–robot interaction. However, there are still some challenges to apply cable-driven parallel robots to rehabilitation, one of which is the geometric calibration. This paper proposes a new automatic calibration method that is applicable for cable-driven parallel rehabilitation robots. The key point of this method is to establish the mapping between the unknown parameters to be calibrated and the parameters that could be measured by the inner sensors and then use least squares algorithm to find the solutions. Specifically, the unknown parameters herein are the coordinates of the attachment points, and the measured parameters are the lengths of the redundant cables. Simulations are performed on a 3-DOF parallel robot driven by four cables for validation. Results show that the proposed calibration method could precisely find the real coordinate values of the attachment points, with errors less than 10 − 12 mm. Trajectory simulations also indicate that the positioning accuracy of the cable-driven parallel robot (CDPR) could be greatly improved after calibration using the proposed method.

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