• Smart Structures and Systems
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• v.25 no.2
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• pp.135-153
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• 2020

There has been a sustained interest towards the non-contact structural displacement measurement by means of videogrammetric technique. On the way forward, one of the major concerns is the spurious image drift induced by temperature variation. This study therefore carries out an investigation into the temperature effect of videogrammetric technique, focusing on the exploration of the mechanism behind the temperature effect and the elimination of the temperature-caused measurement error. 2D videogrammetric measurement tests under monotonic or cyclic temperature variation are first performed. Features of measurement error and the casual relationship between temperature variation and measurement error are then studied. The variation of the temperature of digital camera is identified as the main cause of measurement error. An excellent linear relationship between them is revealed. After that, camera parameters are extracted from the mapping between world coordinates and pixels coordinates of the calibration targets. The coordinates of principle point and focal lengths show variations well correlated with temperature variation. The measurement error is thought to be an outcome mainly attributed to the variation of the coordinates of principle point. An approach for eliminating temperature-caused measurement error is finally proposed. Correlation models between camera parameters and temperature are formulated. Thereby, camera parameters under different temperature conditions can be predicted and the camera projective matrix can be updated accordingly. By reconstructing the world coordinates with the updated camera projective matrix, the temperature-caused measurement error is eliminated. A satisfactory performance has been achieved by the proposed approach in eliminating the temperature-caused measurement error.

• Journal of Korea Game Society
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• v.11 no.4
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• pp.143-149
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• 2011

This paper presents a novel camera tracking method based on model with multiple planes. The proposed algorithm detects QR code that is one of the most popular types of two-dimensional barcodes. A 3D model is imported from the detected QR code for augmented reality application. Based on the geometric property of the model, the vertices are detected and tracked using optical flow. A clipping algorithm is applied to identify each plane from model surfaces. The proposed method estimates the homography from coplanar feature correspondences, which is used to obtain the initial camera motion parameters. After deriving a linear equation from many feature points on the model and their 3D information, we employ DLT(Direct Linear Transform) to compute camera information. In the final step, the error of camera poses in every frame are minimized with local Bundle Adjustment algorithm in real-time.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.4
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• pp.285-297
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• 2000

One of the research objectives in the area of multimedia human-computer interaction is the application of artificial intelligence and robotics technologies to the development of computer interfaces. This involves utilizing many forms of media, integrating speed input, natural language, graphics, hand pointing gestures, and other methods for interactive dialogues. Although current human-computer communication methods include computer keyboards, mice, and other traditional devices, the two basic ways by which people communicate with each other are voice and gesture. This paper reports on research focusing on the development of an intelligent multimedia interface system modeled based on the manner in which people communicate. This work explores the interaction between humans and computers based only on the processing of speech(Work uttered by the person) and processing of images(hand pointing gestures). The purpose of the interface is to control a pan/tilt camera to point it to a location specified by the user through utterance of words and pointing of the hand, The systems utilizes another stationary camera to capture images of the users hand and a microphone to capture the users words. Upon processing of the images and sounds, the systems responds by pointing the camera. Initially, the interface uses hand pointing to locate the general position which user is referring to and then the interface uses voice command provided by user to fine-the location, and change the zooming of the camera, if requested. The image of the location is captured by the pan/tilt camera and sent to a color TV monitor to be displayed. This type of system has applications in tele-conferencing and other rmote operations, where the system must respond to users command, in a manner similar to how the user would communicate with another person. The advantage of this approach is the elimination of the traditional input devices that the user must utilize in order to control a pan/tillt camera, replacing them with more "natural" means of interaction. A number of experiments were performed to evaluate the interface system with respect to its accuracy, efficiency, reliability, and limitation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.347-356
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• 2003

Camera pose and scene geometry estimation from video sequences is widely used in various areas such as image composition. Structure and motion recovery based on the auto calibration algorithm can insert synthetic 3D objects in real but un modeled scenes and create their views from the camera positions. However, most previous methods require bundle adjustment or non linear minimization process [or more precise results. This paper presents a new auto' calibration algorithm for video sequence based on two steps: the one is key frame selection, and the other removes the key frame with inaccurate camera matrix based on an absolute quadric estimation by LMedS. In the experimental results, we have demonstrated that the proposed method can achieve a precise camera pose estimation and scene geometry recovery without bundle adjustment. In addition, virtual objects have been inserted in the real images by using the camera trajectories.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.677-680
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• 2008

Miniaturization of equipments which have wireless network function and sensor have changed utilization method of computer in daily life, and have contributed to development for ubiquitous computing environment. In this paper, we design camera control system based wireless mobile and web-environmental through which nurse, doctor and family of patient can share and observe the information on condition of patient in hospital. Besides, this camera control system makes it possible to integrate diverse equipments of hospital into one system, and to conduct remote control function which can be applied to the patient control system. It is impossible to control shooting direction of camera apparatus in a remote area for observing patient in a hospital room through general web camera. So in this paper, we showed new design; we attached step motor which can rotate 360 degrees to web camera, and the step motor can operate through control board. Besides, we developed application for two environments, mobile and web-based environment, which enables us to offer proper efficiency in accordance with condition of observer through observation of control and collected image data.

• Journal of Broadcast Engineering
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• v.8 no.1
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• pp.63-71
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• 2003

In sport programs, real-time virtual imaging system come into notice for new technology which can compose information like team logos, scores. distances directly on playing ground, so it can compensate for the defects of general character generator. In order to synchronize graphics to camera movements, generally two method is used. One is for using sensors attached to camera moving axis and the other is for analyzing camera video itself. KBS technical research institute developed real-time sensor-based virtual imaging system 'VIVA', which uses four sensors on pan, tilt, zoom, focus axis and controls virtual graphic camera in three dimensional coordinates in real-time. In this paper, we introduce our system 'VIVA' and it's technology. For accurate camera tracking we calculated view-point movement occurred by zooming based on optical principal point variation data and we considered field of view variation not only by zoom but also by focus. We developed our system based on three dimensional graphic environment. so many useful three dimensional graphic techniques such as keyframe animation can be used. VIVA was successfully used both in Busan Asian Games and 2002 presidential election. We confirmed that it can be used not only in the field but also in the studio programs in which camera is used within more close range.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.143-150
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• 2005

Camera image is very sensitive to illumination that result in difficulties for recognizing character. Also Camera captured document images have not only skew but also vignetting effect and geometric distortion. Vignetting effect make it difficult to separate characters from the document images. Geometric distortion, occurred by the mismatch of angle and center position between the document image and the camera, make the shape of characters to be distorted, so that the character recognition is more difficult than the case of using scanner. In this paper, we propose a method that can increase the performance of character recognition by correcting the geometric distortion of document images using a linear approximation which changes the quadrilateral region to the rectangle one. The proposed method also determine the quadrilateral transform region automatically, using the alignment of character lines and the skewed angles of characters located in the edges of each character line. Proposed method, therefore, can correct the geometric distortion without getting positional information from camera.

• International Journal of Control, Automation, and Systems
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• v.3 no.4
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• pp.542-551
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• 2005

A new distance measurement method with the use of a single camera and a rotating mirror is presented. A camera in front of a rotating mirror acquires a sequence of reflected images, from which distance information is extracted. The distance measurement is based on the idea that the corresponding pixel of an object point at a longer distance moves at a higher speed in a sequence of images in this type of system setting. Distance measurement based on such pixel movement is investigated. Like many other image-based techniques, this presented technique requires matching corresponding points in two images. To alleviate such difficulty, two kinds of techniques of image tracking through the sequence of images and the utilization of multiple sets of image frames are described. Precision improvement is possible and is one attractive merit. The presented approach with a rotating mirror is especially suitable for such multiple measurements. The imprecision caused by the physical limit could be improved through making several measurements and taking an average. In this paper, mathematics necessary for implementing the technique is derived and presented. Also, the error sensitivities of related parameters are analyzed. Experimental results using the real camera-mirror setup are reported.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.957-965
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• 2011

Recently, railway industry has been developed not only functional parts such as acceleration and high performance of the railway but also emotional parts such as improved ride comfort and blocking noise. However, some important components of railway such as wheel and rail always had exposed too much operation time, cyclic load and rolling contact directly. The variations of load, vibration and chemical compositions were caused of wheel and rail having a lot of different types of contact fatigue damages. Therefore, It is necessary to improve inspection and maintenance technology in order to ensure safety and reliability of railway. Many researchers have already been reported the technology. Magnetic camera, one of the non-destructive testing technique can be used to inspect and evaluate the changes of magnetic field in ferromagnetic and paramagnetic materials with cracks. When an electromagnetic is applied to a specimen, a magnetic field will be distorted around a crack on the specimen. In present paper, the distribution of magnetic property in wheel with cracks using magnetic camera had investigated. The crack can be detected and evaluated by distribution analysis of magnetic field. The magnetic camera technique can be detected and evaluated the crack by rolling contact fatigue.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1450-1455
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• 2009

Assumed that an IPTV camera system is to be used as an ad-hoc sensor for the surveillance and diagnostics of safety-critical equipments installed in the in-containment building of the nuclear power plant, an major problem is the presence of high dose-rate gamma irradiation fields inside the one. In order to uses an IPTV camera in such intense gamma radiation environment of the in-containment building, the radiation-weakened devices including a CCD imaging sensor, FPGA, ASIC and microprocessors are to be properly shielded from high dose-rate gamma radiation using the high-density material, lead or tungsten. But the passive elements such as mirror, lens and window, which are placed in the optical path of the CCD imaging sensor, are exposed to a high dose-rate gamma ray source directly. So, the gamma-ray irradiation characteristics of the passive elements, is needed to test. A CCD camera lens, made of glass material, have been gamma irradiated at the dose rate of 4.2 kGy/h during an hour up to a total dose of 4 kGy. The radiation induced color-center in the glass lens is observed. The degradation performance of the gamma irradiated lens is explained using an color component analysis.