• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.240-243
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• 1999

본 논문에서는 칼만 필터 방법을 이용하여 견인 어레이의 3차원 형상을 추정하고, 어레이 합성 기법인 ETAM방법이 추정된 3차원 형상에서도 적용 가능함을 입증한다. 기존의 합성 기법들은 모두 견인 어레이가 직선 형태를 유지하고 있다는 가정을 필요로 하지만, ETAM 방법은 3차원 형상추정이 가능한 경우에 그러한 가정이 필요 없게 된다. 단, 3차원 어레이 형상에서 어레이를 확장하기 위해서는 절대 좌표를 추정할 수 있으며, 어레이가 동일한 견인 경로를 따라간다는 가정이 필요하다. 컴퓨터 모의 실험 결과 신호원의 입사각을 추정하였을 때, 주엽폭과 부엽레벨이 감소하는 등 합성이 가능함을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.1-9
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• 2012

A method to estimate the 3-D shape of surface with specular reflection is proposed, where the difference between the images reflected from a flat surface and a curved surface is used. First, we analyzed the geometry of the spatial reflection at specular surface and the variation of reflected light due to curved surface, whose results are used to estimate 3-D shape. The proposed method is shown to be effective via experiments using the illumination with spatially distributed light source and the CCD camera to capture the light reflected from a surface. In experiments, the captured images from curved surface with specular reflection are processed to approximately estimate 3-D shape.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.469-478
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• 2010

This paper proposes the effective shape descriptor for 3D foot pose estimation. To reduce processing time, silhouette-based foot image database is built and meta information which involves the 3D pose of the foot is appended to the database. And we proposed a modified Centroid Contour Distance whose size of the feature space is small and performance of pose estimation is better than the others. In order to analyze performance of the descriptor, we evaluate time and spatial complexity with retrieval accuracy, and then compare with the previous methods. Experimental results show that the proposed descriptor is more effective than the previous methods on feature extraction time and pose estimation accuracy.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.303-315
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• 2007

This paper proposes a 3D structure recovery and registration method that uses four or more common points. For each frame of a given video, a partial structure is recovered using tracked points. The 3D coordinates, camera positions and camera directions are computed at once by our improved scaled orthographic factorization method. The partially recovered point sets are parts of a whole model. A registration of point sets makes the complete shape. The recovered subsets are integrated by transforming each coordinate system of the local point subset into a common basis coordinate system. The process of shape recovery and integration is performed uniformly and linearly without any nonlinear iterative process and without loss of accuracy. The execution time for the integration is significantly reduced relative to the conventional ICP method. Due to the fast recovery and registration framework, our shape recovery scheme is applicable to various interactive video applications. The processing time per frame is under 0.01 seconds in most cases and the integration error is under 0.1mm on average.

• The KIPS Transactions:PartB
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• v.16B no.1
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• pp.47-54
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• 2009

Automatic object recognition in 3D measuring data is of great interest in many application fields e.g. computer vision, reverse engineering and digital factory. In this paper we present a software tool for a fully automatic object detection and parameter estimation in unordered and noisy point clouds with a large number of data points. The software consists of three interactive modules each for model selection, point segmentation and model fitting, in which the orthogonal distance fitting (ODF) plays an important role. The ODF algorithms estimate model parameters by minimizing the square sum of the shortest distances between model feature and measurement points. The local quadric surface fitted through ODF to a randomly touched small initial patch of the point cloud provides the necessary initial information for the overall procedures of model selection, point segmentation and model fitting. The performance of the presented software tool will be demonstrated by applying to point clouds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.241-247
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• 2015

Deflection and deformation occur easily in structures with long length, such as bridges and pipelines. Shape monitoring is required for ensuring their structural health. A fiber Bragg grating (FBG) sensor can be used for monitoring a large-scale structure because of its advantage of multiplexing. In this study, FBG sensors were used for monitoring a composite beam structure, and its strains were measured at multiple points. Thereafter, a shape estimation technique based on the strains was studied. Particularly, a three-dimensional shape estimation technique was proposed for accurate structural health monitoring. A simple experiment was conducted to verify the performance of the shape estimation technique. The result revealed that the estimated shape of the composite beam structure was in agreement with the actual shape obtained after the deformation of the specimen. Additionally, the deflection at a specific point was verified by comparing the estimated and actual deformations measured using a micrometer.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.220-221
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• 2011

본 논문에서는 스마트폰의 카메라와 플래시를 이용한 능동적 3차원 형상 취득 시스템을 제시한다. 두 대의 스마트폰을 이용하여 한 대의 스마트폰은 광원 역할과 광원 위치 추정을 위한 영상 취득을 하고 다른 스마트폰으로 고정된 위치에서 광원의 위치 변화에 따른 영상을 취득을 한다. 각 스마트폰에서 취득된 영상을 마커 기반에서 광원의 위치를 추정하고 카메라의 반응 함수에 의한 비선형적 왜곡과 렌즈의 왜곡을 보정한다. 광원의 방향 벡터와 보정된 영상의 밝기 값을 이용하여 photometric stereo 기법으로 3차원 형상을 취득한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.6
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• pp.27-34
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• 2011

In this paper, we propose an active 3D shape acquisition method based on photometric stereo using camera and flash on a smartphone. Two smartphones are used as the master and slave, in which the slave projects illumination from different locations while the master captures the images and processes photometric stereo algorithm to reconstruct 3D shape. In order to reduce the error, the smartphone's camera is calibrated to overcome the effect of the lens distortion and nonlinear camera sensor response. We apply 5-point algorithm to estimate the pose between smartphone cameras and then estimate lighting direction vector to run the photometric stereo algorithm. Experimental result shows that the proposed system enables us to use smartphone as a 3D camera with low cost and high quality.

• Korean Journal of Optics and Photonics
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• v.27 no.1
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• pp.41-46
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• 2016

An optical method to measure the three-dimensional (3D) shape of a surface with specular reflection is proposed. The proposed method is based on the analysis of the geometric path of the light from a point source, and the relative displacements of points in the reflection image. The 3D shape of a concave mirror is shown to be determined approximately via experiments, where the vision system consists of LED array illumination, a half-mirror, and an imaging sensor.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.47-55
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• 2012

In this paper, we propose a method to reconstruct accurate 3D shape object by using multi-view images which are disturbed by motion blur. In multi-view deblurring, more precise PSF estimation can be done by using the geometric relationship between multi-view images. The proposed method first estimates initial 2D PSFs from individual input images. Then 3D PSF candidates are projected on the input images one by one to find the best one which are mostly consistent with the initial 2D PSFs. 3D PSF consists with direction and density and it represents the 3D trajectory of object motion. 야to restore 3D shape by using multi-view images computes the similarity map and estimates the position of 3D point. The estimated 3D PSF is again projected to input images and they replaces the intial 2D PSFs which are finally used in image deblurring. Experimental result shows that the quality of image deblurring and 3D reconstruction improves significantly compared with the result when the input images are independently deblurred.