• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.5
• /
• pp.134-140
• /
• 2017

Shape-from-shading (SFS) or stereo vision algorithms can be utilized to measure the shape of an object with imaging techniques for effective sensing in non-contact measurements. SFS algorithms could reconstruct the 3D information from a 2D image data, offering relatively comprehensive information. Meanwhile, a stereo vision algorithm needs several feature points or lines to extract 3D information from two 2D images. However, to measure the size of an object with a freeform surface, the two algorithms need some additional information, such as boundary conditions and grids, respectively. In this study, a stereo vision scheme using the depth information obtained by shape-from-shading as patterns was proposed to measure the size of an object with a freeform surface. The feasibility of the scheme was proved with an experiment where the images of an object were acquired by a CCD camera at two positions, then processed by SFS, and finally by stereo matching. The experimental results revealed that the proposed scheme could recognize the size and shape of freeform surface fairly well.

• Proceedings of the IEEK Conference
• /
• 2003.07e
• /
• pp.2379-2382
• /
• 2003

This paper describes the design, implementation and results of a unified non-rigid image registration method for the purposes of 3D shape reconstruction from serial section images. The proposed method uses active contour-based segmentation and compensation of radial distortion. Experimental results show that multiple images can be segmented and reconstructed by active single contour as well as intra- and inter-section registration.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2003.10a
• /
• pp.193-197
• /
• 2003

우수한 문화유산을 보유하고 있는 우리나라는 그간 전쟁과 관리소홀로 인하여 많이 파괴되고 유실되는 피해를 입어왔다. 한번 손실된 문화재는 기존 자료 없이는 완전복구가 어려운 실정이며, 이러한 문화재의 복원을 위해 그 모습을 수치화시켜 영구 보전함으로써 그 활용가치를 높일 수 있다. 또한, 문화재의 복원 전·후의 모습을 체계적으로 정리하기 위해서 문화재의 3차원 구현을 통한 자료의 전산화 작업이 필요하다. 따라서, 본 연구에서는 수치사진측량용 카메라를 이용하여 봉분을 촬영하고, 이렇게 취득 데이터를 사용하여 3차원형상을 수치화 하여 복원 이전의 발굴상태를 영구히 보존함과 동시에 발굴된 유적을 기초로 하여 복원시킨 봉분의 형상을 추측하기는 자료로도 활용할 수 있다. 이러한 복원 작업을 효율적이고, 신속하게 분석하여 재현함으로써 문화재의 유지관리·복원을 위한 기초 자료기반을 구축함에 그 목적이 있다.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.29B no.11
• /
• pp.73-84
• /
• 1992

In this paper, an algorithm for recovering the 3-D shape from a single shaded image is proposed. In the proposed algorithm, by using the relation between the height and surface gradient (p, q), a set of linear equations is derived from the linearized reflectance function. Then the 3-D surface is recovered by employing the conjugate gradient technique. In order to improve the convergence speed of the solution, we also employ the hierarchical basis function and multiresolution images in the algorithm. A method for determining the regularization parameter, which is determined by trial and error in the conventional approach, is also introduced. In addition, the proposed algorithm attempts to recover the 3-D surface without requiring the boundary conditions, making it suitable for a real-time implementation. Simulation results for real image as well as synthetic image are provided to demonstrate the performance of the proposed algorithm.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.12
• /
• pp.21-27
• /
• 1998

This paper recommends the database construction for STL data and the new method of Delaunay's triangulation method in order to decrease volume errors by verifying STL file errors and modifying hole errors. Each vertex for the boundary coordinates of the verified hole errors was analyzed according to the following cases: planes or slow curves, edges, apexes, and rapid curves. In each case, a different modification process was adopted. With this method, most errors resulting from the conversion into the STL data as well as lots of volume errors arising from error modification were decreased.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.7
• /
• pp.1633-1641
• /
• 1996

In this paper we propose a new method for anlayzing the properties of surface reflectance and reconstructing the shape of object using estimated reflectance parameters. We have investigated the hybrid reflectance surface which has specularreflection and diffuse reflection, which can be explained by Torrance-Sparrow model. Sample sphere made on one maerial is used to estimate the reflectance properties by using LMS algorithm. We can make the reference image which consists of surface normal and brightness value using estimated reflectance parameters, and thenarbitrary shape object made of the same material as sample can be reconstructed by matching with reference image. Photometric matching method proposed in this paper is robust because it mateches object image with the reference imageconsidering its neighbor brightness distribution. Also, in this paper plate diffuse illumination is used to remove intensity disparity with simple scheme. It is expected that the proposed algorithm can be applied to 3D recognition, vision inspection system and other fields.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.6
• /
• pp.1089-1094
• /
• 2021

In order to support the restoration and construction work of port infrastructure facilities damaged or damaged due to disasters and disasters, it is linked with work equipment based on the performance of duties such as regular patrol in the port, monitoring the underwater environment, and acquisition of underwater configuration information in the port, Define content related to AUV platform analysis and design that can support construction.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.4
• /
• pp.141-155
• /
• 2018

Recently, the number of ground subsidence resulting from underground cavity has been increased. Accordingly, the importance of restoration of stress release zone around the underground cavity has been emphasized. The stress release zone is composed of low density soils having extremely low stiffness and degree of compaction, which can lead to additional cavity expansion and collapse of overlying ground. Therefore, in this study, the suitability of restoration method of underground cavity using expansive material for reinforcement of stress release zone around the cavity is verified. The basic physical properties and expansion characteristics of the expansive material were examined. The experiment equipment capable simulating of stress release zone was developed and is used to investigate the effect of expanding material on stress release zone. The stress release zone was simulated using the spring in numerical analysis. The factors of the volume ratio of the underground cavity to the expansion material, the degree of stress relaxation, and the shape of the cavity were varied in numerical simulations, and the behavior of stress release zone was analyzed based on the numerical analysis results. Analysis variables are factors that affect each other. Also, filling of underground cavity and capacity of restoration of stress release zone were confirmed when the expansive material was inserted into underground cavity.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.6
• /
• pp.21-29
• /
• 1997

In this paper, we propose a new approach for recovering 3-D shape and extracting the reflectance properties of surface from intensity images. Photometric stereo method(PSM) is genrally based on the direct illumination. In this paper, the reflectance function is derived by interoduceing the indirect diffuse illumination in PSM and then applied to hybrid reflectance model which consists of two components; the lambertian and the specular reflectance. Under the hybrid reflectance model and the indirect diffuse illumination circumstance, the reflectance properties of sample surface can be extracting by normal sampler and then 3-D shape of an object can be recovered based on extracting reflectance properties. This method is rapid because of using the reference table and simplifies the restriction condition about the reflectance function existing in prior studies. Th erecovery efficiency in our method is better than that in prior studies. Also, this method is applied to various types of surfaces by defining general reflectance function.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.1
• /
• pp.55-64
• /
• 2018

The purpose of this study is to evaluate the suitability of emergency underground cavity restoration method filling cavity with expansive material based on numerical analysis. For the numerical analysis, experiments were conducted to evaluate properties of expansive material. Based on the measured expansion pressure of the expansive material from the experiment, behavior of underground cavity restoration with various cavity dimensions (variation of height and width of rectangular-shape cavity) was numerically assessed. As a result of analysis, the vertical displacements of the top and bottom of cavity were significantly influenced by the cavity width and lateral displacements of cavity sides were highly dependent on cavity height. These vertical and lateral displacements were increased with increasing expansion pressure of expansive material. Also, when the expansion pressure was applied, the vertical displacement of the upper surface layer of the road was less dependent on cavity height, and was greatly influenced by cavity width.