• 한국컴퓨터그래픽스학회논문지
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• 제8권3호
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• pp.17-23
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• 2002

영화, 게임, 방송 등의 엔터테인먼트 산업에서 캐릭터 애니메이션에 대한 요구가 증가함에 따라 이를 제작하는 스튜디오에서 모션갭처 장비의 도입을 통해 애니메이션 데이터를 제공하는 사례가 급속히 증가하고 있다. 하지만, 상용 장비들은 고가의 비용 부담으로 인해 엔터테인먼트 산업의 전반적인 매출의 수익창출에 저해요인이 되고 있다. 이러한 배경에서 KAIST VR Lab 에서는 지난 수 년간 저가형 광학식 모션캡처 시스템을 개발하여 왔다. 저가형 시스템을 이용한 경우 마커의 은닉(occlusion), 잡음(noise) 또는 궤적 뒤바뀜(swapping) 등의 이유로 고가의 장비를 사용할 때에 비해 더 많은 후처리 작업을 요한다. 본 논문에서는 이와 같은 문제를 해결하기 위해 인체에 부착된 마커를 그래프 구조로 정의하고 신뢰도 모델을 제시하여 포착된 프레임의 신뢰성을 측정한다. 이러한 신뢰도 모델을 통해 마커의 궤적 재조정(rectification) 알고리즘을 제안한다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권1호
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• pp.41-52
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• 2012

Purpose: Triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline. This point can be fixed as the third point of a triangle with one known side and two known angles. The aim of this study was to find a clinically adaptable method for applying an optical tracking navigation system to orthognathic surgery and to estimate its accuracy of measuring the bone displacement by use of triangulation methods. Methods: In orthognathic surgery, the head position is not fixed as in neurosurgery, so that a head tracker is needed to establish the reference point on the head surface byusing an optical tracking system. However, the operation field is interfered by its bulkiness that makes its clinical use difficult. To solve this problem, we designed a method using an Aquaplast splinting material and a mini-screw in applying a head tracker on a patient's forehead. After that, we estimated the accuracy of measuring displacements of the ball marker by an optical tracking system with a conventional head tracker (Group A) and with a newly designed head tracker (Group B). Measured values of ball markers' displacements by each optical tracking system were compared with values obtained from fusion CT images for an estimation of accuracy. Results: The accuracy of the optical tracking system with a conventional head tracker (Group A) is not suitable for clinical usage. Measured and predictable errors are larger than 10 mm. The optical tracking system with a newly designed head tracker (Group B) shows 1.59 mm, 6.34 mm, and 9.52 mm errorsin threeclinical cases. Conclusion: Most errors were brought on mainly from a lack of reproducibility of the head tracker position. The accuracy of the optical tracking system with a newly designed head tracker can be a useful method in further orthognathic navigation surgery even though the average error is higher than 2.0 mm.

• 정보처리학회논문지B
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• 제17B권5호
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• pp.345-354
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• 2010

시각기반 증강현실을 구현하기 위한 추적 방법들은 정형 패턴 마커를 가정하는 마커 추적기법과 영상 특징점을 추출하여 이를 추적하는 자연특징 추적기법으로 분류된다. 마커 추적기법은 빠른 마커의 추출 및 인식이 가능하여 모바일 기기에서도 실시간 처리가 가능하다. 한편 자연 특징 추적기법의 경우는 입력 영상의 다양성을 고려해야 하므로 계산량이 많은 처리과정을 거쳐야 한다. 따라서 저사양의 모바일 기기에서는 빠른 실시간 처리에 어려움이 있다. 기존의 자연특징 추적에서는 입력되는 카메라 영상의 매 프레임마다 특징점을 추출하고 패턴매칭 과정을 거친다. 다수의 자연특징점들을 추출하는 과정과 패턴매칭 과정은 계산량이 많아 실시간 응용에 많은 제약을 가하는 요인으로 작용한다. 특히 등록된 패턴의 개수가 증가될수록 패턴매칭 과정의 처리시간도 증가하게 된다. 본 논문에서는 이러한 단점을 해결하고자 자연특징 추적 과정에 광류를 사용하여 모바일 기기에서의 실시간 동작이 가능하도록 하였다. 패턴매칭에 사용된 특징점들은 다음의 연속 프레임에서 광류추적 기법을 적용하여 대응점들을 빠르게 찾도록 하였다. 또한 추적 과정에서 소실되는 특징점의 수에 비례하여 새로운 특징점들을 추가하여 특징점의 전체 개수는 일정 수준으로 유지되도록 하였다. 실험 결과 제안하는 추적 방법은 자연특징점 추적 시간을 상당히 단축시킬 뿐만 아니라 카메라 자세 추정 결과도 더욱 안정시킴을 보여주었다.

• Journal of the Optical Society of Korea
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• 제17권2호
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• pp.188-199
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• 2013

This paper presents a novel algorithm for nighttime detection of the lane markers painted on a road at night. First of all, the proposed algorithm uses neighborhood average filtering, 8-directional Sobel operator and thresholding segmentation based on OTSU's to handle raw lane images taken from a digital CCD camera. Secondly, combining intensity map and gradient map, we analyze the distribution features of pixels on boundaries of lanes in the nighttime and construct 4 feature sets for these points, which are helpful to supply with sufficient data related to lane boundaries to detect lane markers much more robustly. Then, the searching method in multiple directions- horizontal, vertical and diagonal directions, is conducted to eliminate the noise points on lane boundaries. Adapted Hough transformation is utilized to obtain the feature parameters related to the lane edge. The proposed algorithm can not only significantly improve detection performance for the lane marker, but it requires less computational power. Finally, the algorithm is proved to be reliable and robust in lane detection in a nighttime scenario.

• Journal of Computing Science and Engineering
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• 제5권3호
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• pp.161-166
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• 2011

We present a fast algorithm for Korean text extraction and segmentation from subway signboards using smart phone sensors in order to minimize computational time and memory usage. The algorithm can be used as preprocessing steps for optical character recognition (OCR): binarization, text location, and segmentation. An image of a signboard captured by smart phone camera while holding smart phone by an arbitrary angle is rotated by the detected angle, as if the image was taken by holding a smart phone horizontally. Binarization is only performed once on the subset of connected components instead of the whole image area, resulting in a large reduction in computational time. Text location is guided by user's marker-line placed over the region of interest in binarized image via smart phone touch screen. Then, text segmentation utilizes the data of connected components received in the binarization step, and cuts the string into individual images for designated characters. The resulting data could be used as OCR input, hence solving the most difficult part of OCR on text area included in natural scene images. The experimental results showed that the binarization algorithm of our method is 3.5 and 3.7 times faster than Niblack and Sauvola adaptive-thresholding algorithms, respectively. In addition, our method achieved better quality than other methods.

• 한국컴퓨터정보학회논문지
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• 제24권1호
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• pp.73-83
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• 2019

In this paper, we propose the augmented reality(AR) based driving navigation based on robust lane detection method to dynamic environment changes. The proposed technique uses the detected lane position as a marker which is a key element for enhancing driving information. We propose Symmetrical Local Threshold(SLT) algorithm which is able to robustly detect lane to dynamic illumination environment change such as shadows. In addition, by using Morphology operation and Connected Component Analysis(CCA) algorithm, it is possible to minimize noises in the image, and Region Of Interest(ROI) is defined through region division using a straight line passing through several vanishing points We also propose the augmented reality aided visualization method for Interchange(IC) and driving navigation using reference point detection based on the detected lane coordinates inside and outside the ROI. Validation experiments were carried out to assess the accuracy and robustness of the proposed system in vairous environment changes. The average accuracy of the proposed system in daytime, nighttime, rainy day, and cloudy day is 79.3% on 4600 images. The results of the proposed system for AR based IC and driving navigation were also presented. We are hopeful that the proposed research will open a new discussion on AR based driving navigation platforms, and thus, that such efforts will enrich the autonomous vehicle services in the near future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.583-585
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• 2004

In this paper we will deal with a calibration method for low cost motion capture system using psd(position sensitive detection) optical sensor. To measure the incident direction of the light from LED emitted marker, the PSD is used the output current ratio on the electrode of PSD is proportional with the incident position of the light focused by lens. In order to defect the direction of the light, the current output is converted into digital voltage value by opamp circuits peak detector and AD converter with the digital value the incident position is measured. Unfortunately, due to the non-linearly problem of the circuit poor position accuracy is shown. To overcome such problems, we compensated the non-linearly by using least-square fitting method. After compensated the non-linearly in the circuit, the system showed more enhanced position accuracy.

• 한국정밀공학회지
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• 제23권3호
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• pp.179-186
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• 2006

Single-walled carbon nanotubes (SWNT) exhibit strong Raman signals as well as fluorescence emissions in the near infrared regions where most biomolecules are transparent. Such signals do not blink or photobleach under prolonged excitation. which is advantageous to optical nano-bio marker applications. In this paper, single walled carbon nanotubes are conjugated with specific types of single-stranded DNA in order to detect oligonucleotides of corresponding complimentary sequences. Dot blotting experiments and comparative Raman spectroscopy observations demonstrated excellent sensitivity and specificity of carbon nanotube-DNA probes. The results show the possibility of using SWNT as generic nano-bio markers for the precise detection of specific kinds of genes.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.8-13
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• 2008

At present many research projects on high-speed spindles are being conducted. These projects require a measurement technique which includes heat expansion, vibration and displacement measurement according to angular velocity. This paper presents the development of a measurement system for high-speed spindle displacement. The measurement system is based on $LabView^{(R)}$ and features the following sensors: optical sensor which reacts to the position of a marker on the spindle and enables two Laser Displacement Sensors(LDS). These Laser Displacement Sensors send their data to a DAQ(Data Acquisition Device). It is important that the delay time caused by the response times of the sensors as well as the sampling rate of the DAQ is considered because the spindle revolves at very high speeds.

• 한국항행학회논문지
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• 제14권2호
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• pp.272-277
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• 2010

증강현실은 실세계의 정보와 가상의 정보를 연결시키기 위한 매개체가 요구되며, 이러한 매개체를 지속적으로 추적 인식하는 기술을 필요로 한다. 이러한 기술 중에 마커를 이용한 광학 트랙킹이 주류를 이루고 있으나 마커를 부착하는 과정이 불편하고 오래 걸리므로 최근에는 마커리스 트랙킹 기법이 활발히 연구되고 있다. 본 논문은 2차원 평면 즉 동일평면상의 특징점들을 트랙킹하는 방법이 아닌3차원 객체에 대한 특징점을 추출하여 실시간으로 트랙킹하는 방법을 제안한다, SURF(Speed Up Robust Features)를 이용하여 특징점을 추출하고 이를 POSIT(Pose Object System for Iteration) 알고리즘으로 3차원 객체의 회전과 이동정보를 얻어 실시간으로 객체를 추적한다. 추적 실패시 실시간으로 재추적이 가능하도록 빠른 특징점 추출과 매칭을 통하여 트랙킹에 적합한 특징점을 선택하여 객체의 위치와 회전 정보를 얻어 객체를 실시간으로 추적 및 재표현 하였다.