• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1749-1752
• /
• 2005

For online high accurate reconstruction of an object from an visual information, a linear reconstruction method for multiple images is popular. Basically this method needs many cameras or many different screen shots from different view points. This method, however, has the benefit of less calculation and is adequate for a real time application by comparing other popular method. In this paper, online reconstruction system using more than three cameras is treated. An evaluation method of cameras' position, and of the number is derived for the linear reconstruction method. To decrease errors that are caused from skew of lens, positional error between corresponding points is taken into consideration on the evaluation. The proposed evaluation method enables estimation of the adequate number of cameras and then of feasible view locations. Additionally, repeating search of epipolar lines enables estimation of the hidden point. Comparing with result of an average error analysis, it was confirmed that the proposed methods works effectively.

• 한국지능시스템학회논문지
• /
• 제20권1호
• /
• pp.101-108
• /
• 2010

본 논문에서는 퍼지 k-NN과 reconstruction error에 기반을 둔 feature selection을 이용한 lazy 분류기 설계를 제안하였다. Reconstruction error는 locally linear reconstruction의 평가 지수이다. 새로운 입력이 주어지면, 퍼지 k-NN은 local 분류기가 유효한 로컬 영역을 정의하고, 로컬 영역 안에 포함된 데이터 패턴에 하중 값을 할당한다. 로컬 영역과 하중 값을 정의한 우에, feature space의 차원을 감소시키기 위하여 feature selection이 수행된다. Reconstruction error 관점에서 우수한 성능을 가진 여러 개의 feature들이 선택 되어 지면, 다항식의 일종인 분류기가 하중 최소자승법에 의해 결정된다. 실험 결과는 기존의 분류기인 standard neural networks, support vector machine, linear discriminant analysis, and C4.5 trees와 비교 결과를 보인다.

• 전자공학회논문지S
• /
• 제34S권6호
• /
• pp.58-66
• /
• 1997

This paper proposes a multiresolution surface parameter estimation method for range images. Based on robust estimation of surface parameters, it approximates a patch to a planar surface in the locally adaptive window. Selection of resolution is made pixelwise by comparing a locally computed homogeneity measure with th eglobal threshold determined by te distribution of the approximation error. The proposed multiresolution surface parameter estimation method is applied to range image reconstruction. Computer simulation results with noisy rnag eimages contaminated by additive gaussian noise and impulse noise show that the proposed multiresolution reconstruction method well preserves step and roof edges compared with the conventional methods. Also the segmentation method based on the estimated surface parameters is shown to be robust to noise.

• ETRI Journal
• /
• 제35권2호
• /
• pp.200-206
• /
• 2013

Most of the literature on compressed sensing has not paid enough attention to scenarios in which the number of acquired measurements is insufficient to satisfy minimal exact reconstruction requirements. In practice, encountering such scenarios is highly likely, either intentionally or unintentionally, that is, due to high sensing cost or to the lack of knowledge of signal properties. We analyze signal reconstruction performance in this setting. The main result is an expression of the reconstruction error as a function of the number of acquired measurements.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 하계종합학술대회 논문집(4)
• /
• pp.35-38
• /
• 2000

The method of Content-based Triangular Mesh Image representation in moving pictures makes better performance in prediction error ratio and visual efficiency than that of classical block matching. Specially if background and objects can be separated from image, the objects are designed by Irregular mesh. In this case this irregular mesh design has an advantage of increasing video coding efficiency. This paper presents the techniques of mesh generation, motion estimation using these mesh, uses image warping transform such as Affine transform for image reconstruction, and evaluates the content based mesh design through computer simulation.

• 로봇학회논문지
• /
• 제11권2호
• /
• pp.51-59
• /
• 2016

In this paper we present (1) analysis of imaging sonar measurement for two-view relative pose estimation of an autonomous vehicle and (2) bundle adjustment and 3D reconstruction method using imaging sonar. Sonar has been a popular sensor for underwater application due to its robustness to water turbidity and visibility in water medium. While vision based motion estimation has been applied to many ground vehicles for motion estimation and 3D reconstruction, imaging sonar addresses challenges in relative sensor frame motion. We focus on the fact that the sonar measurement inherently poses ambiguity in its measurement. This paper illustrates the source of the ambiguity in sonar measurements and summarizes assumptions for sonar based robot navigation. For validation, we synthetically generated underwater seafloor with varying complexity to analyze the error in the motion estimation.

• 한국통신학회논문지
• /
• 제42권5호
• /
• pp.951-958
• /
• 2017

채널 재구성 기법이란 통신시스템에서 의도되지 않은 수신자가 수신 신호로부터 어떤 채널 부호가 사용되었는지, 주요 파라미터는 무엇인지를 알아내는 기법이다. 본 논문은 수신한 신호가 길쌈부호로 부호화된 경우, 사용된 길쌈부호의 주요파라미터인 입출력단의 비트수인 k와 n, 그리고 $k{\times}n$ 생성다항식행렬(Polynomial Generator Matrix, PGM)을 찾아내는 기법에 대해 다룬다. 본 논문은 M. Marazin 등이 제안한, 피버팅을 통한 가우스 조단소거법(Gauss Jordan Elimination Through Pivoting, GJETP)을 사용한 길쌈부호의 채널 재구성 기법에서 채널오류율과 무관하게 임계값을 설정해주던 것과 달리, 수신한 시퀀스로부터 2진 대칭 채널(Bynary Symetric Channel, BSC)의 채널오류확률을 추정하고 이로부터 임계값을 설정하는 방식을 제안하고, S. Shaojing 등의 연판정(soft decision) 값을 이용한 기법을 적용시켜서 채널 재구성 기법의 성공률을 향상시켰다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
• /
• pp.505-508
• /
• 2000

The success of target reconstruction in SAR(Synthetic Aperture Radar) imaging system is greatly dependent on the coherent detection. Primary causes of incoherent detection are uncompensated target or sensor motion, random turbulence in propagation media, wrong path in radar platform, and etc. And these appear as multiplicative phase error to the echoed signal, which consequently, causes fatal degradations such as fading or dislocation of target image. In this paper, we present iterative phase error estimation scheme which uses echoed data in all temporal frequencies. We started with analyzing wave equation for one point target and extend to overall echoed data from the target scene - The two wave equations governing the SAR signal at two temporal frequencies of the radar signal are combined to derive a method to reconstruct the complex phase error function. Eventually, this operation attains phase error correction algorithm from the total received SAR signal. We verify the success of the proposed algorithm by applying it to the simulated spotlight-mode SAR data.

• Journal of the Optical Society of Korea
• /
• 제20권4호
• /
• pp.515-523
• /
• 2016

Spectral reflectance is sparse in space, and while the traditional spectral-reconstruction algorithm does not make full use of this characteristic sparseness, the compressive sensing algorithm can make full use of it. In this paper, on the basis of analyzing compressive sensing based on the orthogonal matching pursuit algorithm, a new algorithm based on the Dice matching criterion is proposed. The Dice similarity coefficient is introduced, to calculate the correlation coefficient of the atoms and the residual error, and is used to select the atoms from a library. The accuracy of Spectral reconstruction based on the pseudo-inverse method, Wiener estimation method, OMP algorithm, and DOMP algorithm is compared by simulation on the MATLAB platform and experimental testing. The result is that spectral-reconstruction accuracy based on the DOMP algorithm is higher than for the other three methods. The root-mean-square error and color difference decreases with an increasing number of principal components. The reconstruction error decreases as the number of iterations increases. Spectral reconstruction based on the DOMP algorithm can improve the accuracy of color-information replication effectively, and high-accuracy color-information reproduction can be realized.

• 한국광학회지
• /
• 제19권6호
• /
• pp.389-393
• /
• 2008

본 논문에서는 컴퓨터 집적영상(integral imaging(II))에서 분산 추정을 이용하여 심하게 은폐된 물체의 복원 시 은폐물(occluding object)의 블러링 효과를 제거하는 방법을 제안하였다. 하나의 요소영상(elemental image) 군으로부터 은폐 효과를 제거하여 복원된 영상의 선명도를 향상시키는 정보를 추출하는 방법을 분석하였다. 이를 실행하기 위해 픽업되는 요소영상들이 높은 해상도, 낮은 초점오차(focus error), 큰 깊이감을 가질 필요가 있다. 요소 영상을 픽업할 때 디지털 컴퓨터를 이용한 synthetic aperture integral imaging(SAII)이 채택되었다. 컴퓨터(Computational) II에서는 복원 면의 위치에 따라 복원되는 영상의 촛첨이 맺히는 영역이 달라진다. 심하게 은폐된 물체 영상의 복원은 은폐 물체의 블러링(bluring) 효과가 복원 면에 전체적으로 크게 나타나기 때문에 선명한 복원을 할 수가 없다. 이러한 은폐물의 블러링 효과가 제거된 복원 영상을 얻기 위해 분산 추정이라는 통계적인 방법이 채택되었다.