• 한국CDE학회논문집
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• 제12권4호
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• pp.283-297
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• 2007

Seamless data integration in the CAx chain of the CAD/CAPP/CAM/CNC has been achieved to a high degree, but research concerning the transfer of data from conceptual sketches to a CAD system should be carried out further. This paper presents a method for reconstructing a 3D model from a freehand sketch. Sketch-based modeling research can be classified into gestural modeling methods and reconstructional modeling methods. This research involves the reconstructional modeling method. Here, Mitani's seminal work, designed for box-shaped 3D model using a predefined template, is improved by leveraging a relational template and specialized for automotive design. Matching between edge graphs of the relational template and the sketch is formulated and solved as the assignment problem using the feature vectors of the edges. Including the stroke preprocessing method required to generate an edge graph from a sketch, necessary procedures and relevant techniques for implementing the template-based modeling method are described. Examples from a working implementation are given.

• 한국CDE학회논문집
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• 제13권4호
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• pp.255-264
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• 2008

Research that reconstructs a 3D model from a freehand 2D sketch has gained attention since 1990s, when data integration in the CAD/CAPP/CAM/CNC chain was an important issue. However, 2D sketches in the conceptual design phase have not been integrated with the downstream CAD/CAPP/CAM/CNC chain. In this paper, we present a method to interface a freehand sketch modeling to commercial CAD systems by mapping a sketch modeling history to the macro parametric history. We use an extended ISO10303-112 standard to represent the modeling history in a gestural modeling system and translate sketch files to neutral macro files. Macro parametric translators are used to translate netural macro files to commercial CAD files.

• Journal of Computational Design and Engineering
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• 제3권3호
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• pp.286-294
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• 2016

In this paper we present an efficient technique for sketch-based 3D modeling using automatically extracted image features. Creating a 3D model often requires a drawing of irregular shapes composed of curved lines as a starting point but it is difficult to hand-draw such lines without introducing awkward bumps and edges along the lines. We propose an automatic alignment of a user's hand-drawn sketch lines to the contour lines of an image, facilitating a considerable level of ease with which the user can carelessly continue sketching while the system intelligently snaps the sketch lines to a background image contour, no longer requiring the strenuous effort and stress of trying to make a perfect line during the modeling task. This interactive technique seamlessly combines the efficiency and perception of the human user with the accuracy of computational power, applied to the domain of 3D modeling where the utmost precision of on-screen drawing has been one of the hurdles of the task hitherto considered a job requiring a highly skilled and careful manipulation by the user. We provide several examples to demonstrate the accuracy and efficiency of the method with which complex shapes were achieved easily and quickly in the interactive outline drawing task.

• Journal of Computational Design and Engineering
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• 제3권2호
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• pp.121-131
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• 2016

Organic modeling of 3D characters is a challenging task when it comes to correctly modeling the anatomy of the human body. Most sketch based modeling tools available today for modeling organic models (humans, animals, creatures etc) are focused towards modeling base mesh models only and provide little or no support to add details to the base mesh. We propose a hybrid approach which combines geometrical primitives such as generalized cylinders and cube with Shape-from-Shading (SFS) algorithms to create plausible human character models from sketches. The results show that an artist can quickly create detailed character models from sketches by using this hybrid approach.

• 한국측량학회지
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• 제35권5호
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• pp.431-438
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• 2017

The information management system for urban planning, urban management and related decision making is increasing an importance in recent years. Especially, the information about 3D buildings in urban area is necessary for urban management related precise location based service. However, it takes a lot of time, effort, and costs to produce 3D modeling data of buildings. These problems have been found in many studies, but the research to solve these problems is still necessary. In this study, we have tested an efficient 3D modeling method of building to solve these problems. SketchUp was used to test 3D modeling methods with OSM(OpenStreetMap) data. The other 3D modeling method using a digital map was tested. The 3D modeling of building data was efficient using PlaceMaker, which can use OSM data. In addition, modeling was possible through simple editing of the digital map and automatic building generation. The efficiency of the research results is presented by comparing with the traditional method based on the regulation and the stadard man power issued by Korean government. These two 3D modeling methods of building tested through the study can be used as basic data for related research and work. Additional studies should be conducted to improve the accuracy of the building model and determine how to obtain height data efficiently.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.103-108
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• 2008

3 차원 공간 모델링을 하기 위한 스케치 시스템의 경우, 3 차원 공간상의 입력 장치를 이용하는 것이 디자이너의 의도를 가장 정확하게 표현할 수 있다. 하지만, 3 차원 공간상의 스케치는 공간 입력 장치의 디자이너 사용에 따라 오차가 방생할 수 있다. 이러한 오차를 줄이기 위하여 디자이너가 일반적으로 사용해 온 드로잉 방식인 다중의 스트로크를 데이터로 사용하여 의도한 모델링을 수행하게 된다. 다중의 스트로크를 실시간으로 처리하기 위해 공간상에 정의된 격자를 이용한 모델링 방식을 사용하였다. 곡면을 구성하기 위한 격자간의 관계 및 다중의 스트로크를 처리하기 위한 주변 격자간의 관계를 정리하고, 이를 이용한 스케치 시스템을 구현하였다.

• 예술인문사회 융합 멀티미디어 논문지
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• 제7권6호
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• pp.701-708
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• 2017

건축공사는 설계단계에서 도면을 바탕으로 예상되는 비용이 산정되며, 소요예산의 책정과 예산에 합당한 효율적 공사 방안을 찾게 된다. 정확한 물량산출과 예산책정은 공사의 수익성 여부를 판단하는 척도 중 하나로 매우 중요하다. 하지만 이러한 과정이 대부분 인력이나 2D 도면에 의존하여 수행되기 때문에 오차가 발생하기 쉬웠고, 자동화가 가능한 BIM(Build Information Modeling) 프로그램은 매우 고가이기 때문에 현장에서 적용하기 어려운 시점이다. 이에 본 연구에서는 3차원 모델링 소프트웨어인 스케치업을 이용하여 3D 건축모델링을 수행하고, 물량산출을 할 수 있는 방법론을 제시하고자 하였다. 연구 결과, 건축물의 2D 도면을 이용하여 효과적으로 3D 모델링을 수행하였으며, 모델링 결과를 기반으로 2D 도면과 3D 모델링을 통한 물량산출의 차이를 산출할 수 있었다. 연구를 통해 스케치업을 활용한 3D 모델링과 물량산출이 기존의 2D 산출식의 오류를 방지할 수 있다는 가능성을 제시하였다. 지속적인 연구를 통해 연구방법의 활용성이 검증된다면 건축 모델링과 물량산출 업무 효율성 증가에 크게 기여할 것이다.

• International Journal of CAD/CAM
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• 제11권1호
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• pp.18-26
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• 2011

This paper proposes a new solid-shape modeling system based on a lusterware-image illustration. The proposed method reconstructs a three dimensional solid shape from a set of rough sketches that are typically drawn in the early stages of the design process. The sketches do not have to be strictly accurate, and this tolerance to the roughness of the input sketches is one of the major advantages of the proposed method. The proposed system creates an initial shape based on the silhouette of the input lusterware-images. Then the user can edit the initial shape with intuitive cutting and dishing-up operations, which are based on sketching user interface. To achieve the goal, the system retains the geometric model with two representations: a point-set data and a volume data. This dual data structure allows the program to create an initial shape from the input images with little computational cost, and the user can apply cutting and dishing-up operations without substantially increasing computational and memory requirements. In this research, we have tested the proposed system by reconstructing solid models of some mechanical parts from rough sketches. The experimental results indicate that the proposed method is useful for the prototyping of a solid shape.

• Journal of Computational Design and Engineering
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• 제2권1호
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• pp.67-72
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• 2015

Recently, along with the improvements of geometry modeling methods using sketch-based interface, there have been a lot of developments in research about generating surface model from 3D curves. However, surfacing a 3D curve network remains an ambiguous problem due to the lack of geometric information. In this paper, we propose a new algorithm for estimating the normal vectors of the 3D curves which accord closely with user intent. Bending energy is defined by utilizing RMF(Rotation-Minimizing Frame) of 3D curve, and we estimated this minimal energy frame as the one that accords design intent. The proposed algorithm is demonstrated with surface model creation of various curve networks. The algorithm of estimating geometric information in 3D curves which is proposed in this paper can be utilized to extract new information in the sketch-based modeling process. Also, a new framework of 3D modeling can be expected through the fusion between curve network and surface creating algorithm.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권3호
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• pp.217-225
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• 2009

디자이너가 생각하는 모델을 3차원 입력 장치를 사용하여 공간상에서 스케치를 할 경우 상대적으로 깊이 방향의 위치를 정확히 입력하기 어렵기 때문에 원하는 모델을 단시간에 그리기 어렵다. 본 논문에서는 2차원 스케치에서 습관적으로 사용하는 다중, 반복 스트로크를 공간 스케치 시스템에 적용하여 입력 위치의 에러를 보정함과 동시에 효율적으로 개념상의 모델을 실체화 할 수 있는 모델링 알고리즘을 제안한다. 디자이너는 곡면을 그리기 위하여 스트로크를 입력한 후 바로 그 결과를 확인할 수 있으며, 추가적인 스트로크를 입력할 때마다 곡면은 변형되고 자신이 원하는 형태로 변형되는 지 확인하면서 새로운 스트로크를 입력할 수 있다. 이를 위하여 드로잉 공간을 격자 형태의 공간으로 나누고, 각각의 격자 내부에는 격자안에서 이동이 자유로운 내부 정점을 정의하여 드로잉 공간에서의 데이타를 단순화하였다. 이정점을 인접격자와의 상호관계 패턴으로 정의하여 디자이너가 의도한 개념상의 모델을 효과적으로 3차원모델로 구체화하는 3차원 공간 스케치 시스템을 구현하였다.