• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.601-606
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• 2013

3D scanning is a technique to measure the 3D shape information of the object. Shape information obtained by 3D scanning is expressed either as point cloud or as polygon mesh type data that can be widely used in various areas such as reverse engineering and quality inspection. 3D scanning should be performed as accurate as possible since the scanned data is highly required to detect the features on an object in order to scan the shape of the object more precisely. In this study, we propose the method on finding the location of feature more accurately, based on the extended Biplane SNAKE with global optimization. In each iteration, we project the feature lines obtained by the extended Biplane SNAKE into each image plane and move the feature lines to the features on each image. We have applied this approach to real models to verify the proposed optimization algorithm.

• Korean Journal of Heritage: History & Science
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• v.57 no.1
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• pp.82-108
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• 2024

With the transition of archaeological recording method's transition from analog to digital, the 3D scanning technology has been actively adopted within the field. Research on the digital archaeological digital data gathered from 3D scanning and photogrammetry is continuously being conducted. However, due to cost and manpower issues, most buried cultural heritage organizations are hesitating to adopt such digital technology. This paper aims to present a digital recording method of relics utilizing open-source software and photogrammetry technology, which is believed to be the most efficient method among 3D scanning methods. The digital recording process of relics consists of three stages: acquiring a 3D model, creating a joining map with the edited 3D model, and creating an digital drawing. In order to enhance the accessibility, this method only utilizes open-source software throughout the entire process. The results of this study confirms that in terms of quantitative evaluation, the deviation of numerical measurement between the actual artifact and the 3D model was minimal. In addition, the results of quantitative quality analysis from the open-source software and the commercial software showed high similarity. However, the data processing time was overwhelmingly fast for commercial software, which is believed to be a result of high computational speed from the improved algorithm. In qualitative evaluation, some differences in mesh and texture quality occurred. In the 3D model generated by opensource software, following problems occurred: noise on the mesh surface, harsh surface of the mesh, and difficulty in confirming the production marks of relics and the expression of patterns. However, some of the open source software did generate the quality comparable to that of commercial software in quantitative and qualitative evaluations. Open-source software for editing 3D models was able to not only post-process, match, and merge the 3D model, but also scale adjustment, join surface production, and render image necessary for the actual measurement of relics. The final completed drawing was tracked by the CAD program, which is also an open-source software. In archaeological research, photogrammetry is very applicable to various processes, including excavation, writing reports, and research on numerical data from 3D models. With the breakthrough development of computer vision, the types of open-source software have been diversified and the performance has significantly improved. With the high accessibility to such digital technology, the acquisition of 3D model data in archaeology will be used as basic data for preservation and active research of cultural heritage.

• Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.96-104
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• 2015

Aluminum die casting is an important manufacturing process for mechanical components. Die casting is known to be more accurate than other types of casting; however, post-machining is usually necessary to achieve the required accuracy. The goal of this investigation is to develop machining- free aluminum die casting. Improvement of the accuracy of planar and cylindrical parts is expected by correcting metal molds. In the proposed method, the shape of cast aluminum made with the initial metal molds is measured by 3D scanning. The 3D scan data includes information about deformations that occur during casting. Therefore, it is possible to estimate the deformation and correction amounts by comparing 3D scan data with product computer-aided design (CAD) data. We corrected planar and cylindrical parts of the CAD data for the mold. In addition, we corrected the planar part of the metal mold using the corrected mold data. The effectiveness of the proposed method is demonstrated by evaluating the accuracy improvement of the cast aluminum made with the corrected mold.

• Geophysics and Geophysical Exploration
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• v.6 no.1
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• pp.35-39
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• 2003

A software to visualize and analyse 3-D seismic data is developed using OpenGL, one of the most popular 3-D graphic library, under the PC and Windows platform. The software can visualize the data as volume and slices, whose color distribution is specified by a special dialog box that can pick a color in RGB or HSV format. The dialog box can also designate opacity values so that several 3-D objects can be displayed superimposed each other. Horizon picking is implemented very easily with this software thanks to the guided picking method. The picked points from a horizon will compose a set of points, mesh, and a surface, which can be viewed and analysed in three dimensions.

• Economic and Environmental Geology
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• v.19 no.spc
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• pp.227-237
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• 1986

The Duk-Eum mine located in Kongsan-myeon, Naju-gun, Cheolanamdo is producing silver ore mainly, with rare gold association. The grade-up and recovery of the concentrates have been concerned to the main problem. And then, this study aimed at applying the basic data for ore processing. In the first half of the study, the attempts were made to identify the ore minerals, this followed by determination of the mineral texture, paragenesis, grain size, and size distribution by employing the microscopical method and the etching test. The results of the study are as follows: 1. The ore deposit is composed of the hydrothermal fissure linked veins, and filling cavities are mostly tensile fractures or joints, in rhyolitic rocks as a wall rock. 2. The principle ore minerals are native silver, acanthite, canfieldite, pyrargyrite, galena, tetrahedrite, sphalerite, pyrrhotite, chalcopyrite, chalcocite, covellite, zincite, and the gangue minerals are quartz and calcite. 3. The grain size of each ore minerals before grinding are; max. $2\frac{1}{2}$ mesh, medium 48-100 mesh(main size, contained over 80%), min. 3200mesh. And the grain size of each ore minerals after grinding is; max. 42mesh, medium 65-250mesh(main size, contained over 80%), min. 3200mesh. 4. The properties of the mineral texture effected on the ore dressing are follows; a) Inclusion texture; the fine grains of chalcopyrite is included in most acanthite, and rarely, that of galena included in acanthite. b) Exsolution texture; pyrargyrite is exsolved in acanthite. c) Replacement texture; native silver replaced pyrargyrite, and acanthite replaced galena. d) Interlocking paragenetic texture; the interlocking paragenetic minerals are pyrite, chalcopyrite, chalcocite, canfieldite. e) Fissure filling texture; chalcopyrite was filled along the cracks in acanthite. Among of the above texture, it is impossible to liberate the grains of a), and more difficult to liberate those of b) and c), while easy to liberate those of d) and e).

• Journal of Korea Multimedia Society
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• v.23 no.8
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• pp.903-914
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• 2020

In this paper, we present a novel algorithm to generate a 3D model of patient-specific orbital implant, which is finally produced by the 3D printer. Given CT (computed tomography) scan data of the defective orbital wall or floor, we compose the depth image of the defect site by using the depth buffering, which is a computer graphics technology. From the depth image, we compute the 3D surface which fills the broken part by interpolating the points around the broken part. By thickening the 3D surface, we get the 3D volume mesh of the orbital implant. Our algorithm generates the patient-specific orbital implant whose shape is accurately coincident to the broken part of the orbit. It provides the significant time efficiency for manufacturing the implant with supporting high user convenience.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.6
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• pp.874-880
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• 2018

3D modeling is extensively used in the field of architecture, machinery and contents production such as movies. Modeling is a time-consuming task. In order to compensate for these drawbacks, attempts have recently been made to reduce the production period by applying 3D scanning technology. 3D scanning for small objects can be done directly with laser or optics, but large buildings and sculptures require expensive equipment, which makes it difficult to acquire data directly. In this study, 3D modeling data for a large object is acquired using photometry with using drones to acquire the image data. The maintenance method for uniform spacing between the sculpture and the drone, the measurement method for the flight line were presented. In addition, we presented a production environment that can utilize the obtained 3D point cloud data for animation and a rendered animation result to find ways to make it in various environments.

• Proceedings of the IEEK Conference
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• summer
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• pp.361-364
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• 2004

This paper describes an automatic 3D models generation algorithm based on 2D silhouette images, using X-ray camera without camera parameters. The algorithm takes a multi steps process approach. First, a series of 2D silhouette images is captured from different directions of object and then converted to binary images. An octree data structure is constructed for voxel-based representation of object. An estimate 3D volume of object can be reconstructed by intersecting voxels and the 2D silhouettes. The marching cube algorithm is applied to get triangle mesh representing of the obtained 3D model for rendering.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.22-29
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• 2002

This paper presents an algorithm for segmentation of 3D triangular mesh data. The proposed algorithm uses iterative merging of adjacent triangle pairs based on the orientation of triangles. The surface is segmented into patches, where each patch has a similar normal property Thus, each region can be approximated to planar patch and its boundaries have perceptually important geometric information of the entire mesh model. The experimental results show that the Proposed algorithm is peformed efficiently.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.579-585
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• 2016

3D laser scanning can be used for scanning the freeform surface and building a model from which the measurements could be taken, in order to solve the difficulty with getting access to the exact freeform shape and position data of the complex building envelope. The shape making process using 3D scanning is as follows: point cloud, mesh surface segmentation, NURBS(Non-Uniform Rational B-spline) surface generation, and parametric solid model generation. In this research, we review previous studies, reverse engineering notion, importance of reverse engineering usage for freeform envelope, and previous cases in order to identify the detail reverse engineering process for prefabrication and construction of freeform panels using 3D laser scanning technology. Therefore, the purpose of this research is to present a basic information which should be considered during design and construction phase and improve quality and constructibility of freeform building by analyzing the reverse engineering process and case study for prefabrication and construction of freeform panels using 3D laser scanning. The research results will enable 3D shape engineering and design parameterization using reverse engineering to be used in various construction projects.