• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1923-1928
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• 2017

This paper is a study on error correction for three-dimensional shape reconstruction based on factorization method. The existing error correction method based on factorization has a limitation of correction because it is optimized globally. Thus in this paper, we propose our new method which can find and correct the only major error influence factor toward three-dimensional reconstructed shape instead of global approach. We define the error-influenced factor in two-dimensional re-projection deviation space and directly control the error components. In addition, it is possible to improve the error correcting performance by recursively applying the above process. This approach has an advantage under noise because it controls the major error components without depending on any geometric information. The performance evaluation of the proposed algorithm is verified by simulation with synthetic and real image sequence to demonstrate noise robustness.

• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.73-82
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• 2009

This paper proposes a variance recovery method for character strokes that can be missed in applying the previously proposed color variance approach in text detection of natural scene images. The previous method has a shortcoming of missing the color variance due to the fixed length of horizontal and vertical windows of variance detection when the character strokes are thick or long. Thus, this paper proposes a variance recovery method by using geometric information of bounding boxes of connected components and heuristic knowledge. We have tested the proposed method using various kinds of document-style and natural scene images such as billboards, signboards, etc captured by digital cameras and mobile-phone cameras. And we showed the improved text detection accuracy even in the images of containing large characters.

• Spatial Information Research
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• v.9 no.1
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• pp.1-13
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• 2001

Nowadays, SAR Interferometry is actively being studied as a new technique in topographic mapping using satellite imagery. It extracts height values using phase information derived by two SAR imageries covering same areas. Unlike when using SPOT imagery, it is not affected by atmospheric conditions and time. So to speak, we can say that SAR Interferometry is flexible in imagery acquisitions and can get height data economically over wide area. So, it is expected that SAR Interferometry will be widely using in GIS applications. But, in some area occurring geometric distortion, height data are misjudged or not extracted depending on phase unwrapping algorithms. IN the case of ERS tandem data, the accuracy of height data was worst in mountain area. It is the because of the short incidence angle resulted in layover effect. Of the phase unwrapping algorithms, path-following was better in height accuracy but could not get data in layover area. In this area, we could get height data using Height Sensitivity. In concludion, we could get DEM that maintained the accuracy of path-following method and have overall data across imagery.

• Smart Media Journal
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• v.3 no.4
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• pp.22-27
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• 2014

Three-dimensional image reconstruction allows us to represent real objects in the virtual space and observe the objects at arbitrary view points. This technique can be used in various application areas such as education, culture, and art. In this paper, we propose an implementation method of the high-quality three-dimensional object using multiple Kinect cameras released from Microsoft. First, We acquire color and depth images from triple Kinect cameras; Kinect cameras are placed in front of the object as a convergence form. Because original depth image includes some areas where have no depth values, we employ joint bilateral filter to refine these areas. In addition to the depth image problem, there is an color mismatch problem in color images of multiview system. In order to solve it, we exploit an color correction method using three-dimensional geometry. Through the experimental results, we found that three-dimensional object which is used the proposed method is more naturally represented than the original three-dimensional object in terms of the color and shape.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.29-46
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• 2004

It is important to identify geometries of fracture that act as a conduit of fluid flow for characterization of ground water flow in fractured rock. Fracture geometries control hydraulic conductivity and stream lines in a rock mass. However, we have difficulties to acquire whole geometric data of fractures in a field scale because of discontinuous distribution of outcrops and impossibility of continuous collecting of subsurface data. Therefore, it is needed to develop a method to describe whole feature of a target fracture geometry. This study suggests a new approach to develop a method to characterize on the whole feature of a target fracture geometry based on the Fourier transform. After sampling of specimens along a target fracture from borehole cores, effective frequencies among roughness components were selected by the Fourier transform on each specimen. Then, the selected effective frequencies were averaged on each frequency. Because the averaged spectrum includes all the frequency profiles of each specimen, it shows the representative components of the fracture roughness of the target fracture. The inverse Fourier transform is conducted to reconstruct an averaged whole roughness feature after low pass filtering. The reconstructed roughness feature also shows the representative roughness of the target subsurface fracture including the geometrical characteristics of each specimen. It also means that overall roughness feature by scaling up of a fracture. In order to identify the characteristics of permeability coefficients along the target fracture, fracture models were constructed based on the reconstructed roughness feature. The computation of permeability coefficient was performed by the homogenization analysis that can calculate accurate permeability coefficients with full consideration of fracture geometry. The results show a range between $10^{-4}{\;}and{\;}10^{-3}{\;}cm/sec$, indicating reasonable values of permeability coefficient along a large fracture. This approach will be effectively applied to the analysis of permeability characteristics along a large fracture as well as identification of the whole feature of a fracture in a field scale.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.508-510
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• 2001

3차원 물체의 인식과 공간 정보를 추출해 내는 것이 물체인식의 주요 목적이다. 본 논문에서는 평면의 표면을 갖는 기하학적 물체들을 인식하는데 인공신경망이 적용 가능함이 조사되었다. 물체인식을 위한 모델들은 CAD모델들로부터 자동적으로 추출되며, 획득된 물체의 영상과 일치하는 물체의 국면(aspect)과의 매칭은 조건만족 인경신경망을 이용하여 매칭-오차를 최소화시키는 방법을 처리되었다. 인식된 물체의 국면이 어느 방향에서 획득되었는지에 대한 정보(Aspect's view direction)는 검색된 가시 평면들의 분포로부터 추출됨을 ART와 같은 인공신경망을 이용하여 실시간으로 복원할 수 있음을 보였다. 대표적이 측정방향과 이 측정방향으로부터의 편차들을 한 범주에 넣고 학습을 통해 정확한 측정방향 정보들을 구하며, 획득된 3차원 물체의 영상들에 따라 자동적으로 측정방향범주 들이 추가되도록 한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.55-58
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• 2016

본 논문은 사람의 얼굴 영상에서 잡티를 제거하는 방법을 제안한다. 먼저 입력받은 영상에서 Haar-like Feature 기반 Adaboost 알고리즘과 색상 정보를 이용하여 얼굴 영역을 검출한다. 검출된 얼굴 영역에서 잡티를 제거하기 위해서는 먼저 눈, 코, 입, 눈썹과 같은 얼굴의 주요부위를 검출하고 이 영역을 제외한 순수 피부 영역에 잡티 검출 알고리즘을 적용해야한다. 사람의 얼굴은 미세하게 명암도 차이가 나는 부분이 많기 때문에 가우시안 스무딩을 적용한 후, 그래프 기반 분할 방법을 사용하여 눈, 입, 눈썹을 분할한다. 코 영역은 각 픽셀에 대해 인접픽셀과의 R 채널의 차이값을 가중치 맵으로 만들고 가중치 맵을 분석하여 영역을 분할한다. 분할된 영역에 사람 얼굴의 기하학적 위치 정보를 이용하여 주요부위를 검출한다. 얼굴의 주요부위를 검출하고 그 부위를 제외한 피부 영역에 잡티 검출 알고리즘을 적용한다. 잡티는 Edge와 색상 정보를 이용하여 검출하고, 잡티주변을 검사하여 잡티가 아닌 깨끗한 피부를 잡티 영역에 복사하여 채워나가는 방식으로 피부 영역을 복원한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.454-456
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• 2002

인터넷의 발달로 인하여 웹을 통한 문서 송수신이 많아지면서 이메일의 사용자도 기하급수적으로 늘어나고 있다. 또한 전자상거래에서 무수한 개인적, 직접적 정보 서비스를 이메일로 이용하게 됨에 따라 빠르고 정확한 전송시스템이 현안이 되고 있다. 특히 전자상거래의 상업적 메일은 대량의 메일을 항상 송신해야 하고, 멀티미디어 자료들이 내재되어 있어 메일 용량이 커져서 메일 전송 시 많은 부하가 발생할 수밖에 없는 현실이다. 본 연구는 이러한 문제를 해결하기 위하여 전자상거래의 메일 특수성에 맞춰 템플릿(template)기반 메일 전송방법을 제안하고자 한다. 이는 시간 축을 기준으로 각각의 클라이언트에게 보내는 내용이 같은 항목 하에 일부 내용만이 바뀌는 수평적 유사성(horizontal similarity), 보내지는 폼의 전체적인 디자인 변화나 회사의 정보가 변경되는 수직적 유사성(vertical similarity)특징을 이용한다. 유사성을 가진 메일을 보낼 때 하나의 템플릿으로 작성해서 보내게 되면, 그 이후에는 템플릿 외 사용자 정보만을 전송하게 되며, 메일클라이언트는 컴퓨터에서 이러한 템플릿을 가지고 원래의 메일로 복원을 하게 된다. 이는 전체적인 메일 전송량을 현저하게 줄일 수 있게 해 준다.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06c
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• pp.549-554
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• 2008

도시와 같은 광범위한 영역에 대한 지형, 지물의 기하 정보를 추출 또는 복원하는 기술은 공간 영상정보 시스템을 비롯한 다양한 응용분야에서 사용되고 있으며, 이러한 필요에 따라 중요성이 더욱 커지고 있다. 본 논문은 위성 영상에서 건물의 footprint와 rooftop, 그림자 정보를 이용하여 건물을 반 자동으로 모델링하고, 이를 지형에 정합하는 시스템을 제안한다. 제안하는 시스템은 사용자의 직접적인 조작과 자동으로 이루어는 부분을 조합하여, 최소한의 사용자 조작으로 건물을 모델링하고, 지형에 의한 요소를 고려하여 건물의 실제 위치를 보정하여 지형과 정합을 수행한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.527-535
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• 2016

Statistical optimization algorithms have been variously developed to estimate the 3D shape and motion. However, statistical approaches are limited to analyze the sensitive effects of SfM(Shape from Motion) according to the camera's geometrical position or viewing angles and so on. This paper propose the quantitative estimation method about the uncertainties of an observation matrix by using camera imaging configuration factors predict the reconstruction ambiguities in SfM. This is a very efficient method to predict the final reconstruction performance of SfM algorithm. Moreover, the important point is that our method show how to derive the active guidelines in order to set the camera imaging configurations which can be expected to lead the reasonable reconstruction results. The experimental results verify the quantitative estimates of an observation matrix by using camera imaging configurations and confirm the effectiveness of our algorithm.