• 센서학회지
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• 제23권1호
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• pp.66-71
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• 2014

Vision is the most important sensing capability for both men and sensory smart machines, such as intelligent robots. Sensed real 3D world and its 2D camera image can be related mathematically by a process called camera calibration. In this paper, we present a novel linear solution of camera calibration. Unlike most existing linear calibration methods, the proposed technique of this paper can identify camera parameters explicitly. Through the step-by-step procedure of the proposed method, the real physical elements of the perspective projection transformation matrix between 3D points and the corresponding 2D image points can be identified. This explicit solution will be useful for many practical 3D sensing applications including robotics. We verified the proposed method by using various cameras of different conditions.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.118-121
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• 2007

In recent years, the hyperspectral instruments with high spatial and high spectral resolution have become an important component of wide variety of earth science applications. The primary mission of the proposed Compact Airborne Imaging Spectrometer System (CAISS) in this study is to acquire and provide full contiguous spectral information with high quality spectral and spatial resolution for advanced applications in the field of remote sensing. The CAISS will also be used as the vicarious calibration equipment for the cross-calibration of satellite image data. The CAISS consists of six physical units: the camera system, the Jig, the GPS/INS, the gyro-stabilized mount, the operating system, and the power inverter and distributor. Additionally, the calibration instruments such as the integrated sphere and spectral lamps are also prepared for the radiometric and spectral calibration of the CAISS. The CAISS will provide high quality calibrated image data that can support evaluation of satellite application products. This paper summarizes the design, development and major characteristic of the CAISS.

• 한국정밀공학회지
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• 제16권3호통권96호
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• pp.198-207
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• 1999

This paper presents an accurate algorithm for geometric calibration of X-ray imaging system. Calibration is a very important process for improving an imaging system performance. There has been a lot of previous works using linear camera modeling technique, where lens distortion is neglected and/or center of distortion is assumed to be known. Geometrical distortion of image intensifier, however, is very large and its center of distortion should be calculated. This paper presents a new calibration method to estimate the intensifier position and orientation, scale factor, distortion coefficient, magnification factor, and center of distortion using the least square method. We investigate the properties of the algorithm by computer simulation. Simulation results show that the parameters can be estimated accurately using the proposed algorithm.

• 제어로봇시스템학회논문지
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• 제8권9호
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• pp.803-811
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• 2002

Machine vision systems are usually used to identify traffic lanes and then determine the steering angle of an autonomous vehicle in real time. The steering angle is calculated using a geometric model of various parameters including the orientation, position, and hardware specification of a camera in the machine vision system. To find the accurate values of the parameters, camera calibration is required. This paper presents a new camera-calibration algorithm using known traffic lane features, line thickness and lane width. The camera parameters considered are divided into two groups: Group I (the camera orientation, the uncertainty image scale factor, and the focal length) and Group II(the camera position). First, six control points are extracted from an image of two traffic lines and then eight nonlinear equations are generated based on the points. The least square method is used to find the estimates for the Group I parameters. Finally, values of the Group II parameters are determined using point correspondences between the image and its corresponding real world. Experimental results prove the feasibility of the proposed algorithm.

• Current Optics and Photonics
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• 제5권5호
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• pp.524-531
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• 2021

In an integral-imaging microscopy (IIM) system, a microlens array (MLA) is the primary optical element; however, surface errors impede the resolution of a raw image's details. Calibration is a major concern with regard to incorrect projection of the light rays. A ray-tracing-based calibration method for an IIM camera is proposed, to address four errors: MLA decentering, rotational, translational, and subimage-scaling errors. All of these parameters are evaluated using the reference image obtained from the ray-traced white image. The areas and center points of the microlens are estimated using an "8-connected" and a "center-of-gravity" method respectively. The proposed approach significantly improves the rectified-image quality and nonlinear image brightness for an IIM system. Numerical and optical experiments on multiple real objects demonstrate the robustness and effectiveness of our proposed method, which achieves on average a 35% improvement in brightness for an IIM raw image.

• 대한공간정보학회지
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• 제1권2호
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• pp.153-158
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• 1993

주사기(scanner)에 의해 수치영상자료를 취득하는 과정에 있어서 기존 사진이나 도면의 좌표체계는 수치영상의 좌표체계로서 변환되므로 이들 좌표체계 간의 변환관계를 설정하는 것은 매우 중요한 일이다. 또한 주사기의 주사운동에 따라 왜곡이 발생할 수 있으므로 이를 보정하기 위한 연구도 이루어져야 한다. 본 연구에서는 항공사진을 주사기에 의해 수치화하는 과정에서의 좌표계의 변환관계를 설정하고 주사기의 왜곡을 검정하기 위한 최적검정모형식을 결정하는 과정을 수행하였다. 그 결과 본 연구에 이용된 주사기에 대한 최적검정모형식이 결정되었다. 또한, 본 연구의 수행과정은 기하학적인 해석을 통하여 검정을 수행하였으므로 타 기종의 주사기를 검정하는 데 있어서도 적용이 가능하다.

• 대한디지털의료영상학회논문지
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• 제13권1호
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• pp.39-48
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• 2011

Uses a Tomographic scan image and Table Object Distance(TOD) price after measuring, uses accuracy and usability of blood vessel diameter(Vessel Diameter) measurement under comparison evaluating boil TOD Calibration. The patient who enforces Prosecuting Attorney abdomen Tomographic scan in the object the superior mesentery artery uses PACS View from abdomen fault image and from blood vessel diameter and the table measures the height until of the blood vessel. Uses Angio Catheter from Angiography(5 Fr.) and enforces is measured from PACS View the height until of the table which and the blood vessel at TOD Calibration price and the size of the superior mesentery artery inputs measures an superior mesentery artery building skill. Catheter Calibration input Agnio Catheter where uses in Angiography the size of the superior mesentery artery at Catheter Calibration price and they measure. Produced an accuracy from monitoring data and comparison evaluated. The statistical program used SPSS. TOD Calibration accuracy was 96.53%, standard deviation is 0.03829. Catheter Calibration accuracy of 92.91%, standard deviation is 0.05085. Represents a statistically significant difference(p = 0). According to age and gender was not statistically significant(p > 0.05). TOD Calibration correlation coefficient R-squared of 88.8%, Catheter Calibration of the R-squared is 75.5%. High accuracy of both methods. Through this study, CT images using the measured distance between the table and the Object, TOD Calibration accuracy higher than two Catheter Calibration was measured. TOD and Catheter Calibration represents a statistically significant difference(p = 0).

• 한국전기전자재료학회논문지
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• 제34권5호
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• pp.371-381
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• 2021

A machine vision inspection system consists of a camera, optics, illumination, and image acquisition system. Especially a scanning system has to be made to measure a large inspection area. Therefore, a machine vision line scan camera needs a line scan light source. A line scan light source should have a high light intensity and a uniform intensity distribution. In this paper, an offset calibration and slope calibration methods are introduced to obtain a uniform light intensity profile. Offset calibration method is to remove the deviation of light intensity among channels through adding intensity difference. Slope calibration is to remove variation of light intensity slope according to the control step among channels through multiplying slope difference. We can obtain an improved light intensity profile through applying offset and slope calibration simultaneously. The proposed method can help to obtain clearer image with a high precision in a machine vision inspection system.

• 한국CDE학회논문집
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• 제9권4호
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• pp.397-405
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• 2004

Texture mapping is the process of covering 3D models with texture images in order to increase the visual realism of the models. For proper mapping the coordinates of texture images need to coincide with those of the 3D models. When projective images from the camera are used as texture images, the texture image coordinates are defined by a camera calibration method. The texture image coordinates are determined by the relation between the coordinate systems of the camera image and the 3D object. With the projective camera images, the distortion effect caused by the camera lenses should be compensated in order to get accurate texture coordinates. The distortion effect problem has been dealt with iterative methods, where the camera calibration coefficients are computed first without considering the distortion effect and then modified properly. The methods not only cause to change the position of the camera perspective line in the image plane, but also require more control points. In this paper, a new iterative method is suggested for reducing the error by fixing the principal points in the image plane. The method considers the image distortion effect independently and fixes the values of correction coefficients, with which the distortion coefficients can be computed with fewer control points. It is shown that the camera distortion effects are compensated with fewer numbers of control points than the previous methods and the projective texture mapping results in more realistic image.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.207-212
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• 1997

In estimating the formability of sheet metal, the stereo vision system contributes the accuracy of strain of sheet metal, the convenience in measuring the strain of sheet metal, and the handiness in preparing the forming limit diagram by calculating the 3D values and strain of sheet metal. The algorithm has been developed so that the 3D-coordinate values of sheet metal could be calculated by image processing which is composed of camera calibration, and the stereo matching of images in two viewpoints. By comparing with experiments, the possibility and the convenience of algorithm has been verified, which could calculate the 3D-coordinate values of sheet metal automatically by using the preprocessing of the original image of sheet metal, which had the noise before adjusting the camera calibration and the stereo matching algorithm.