• Journal of the Korea Computer Graphics Society
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• v.20 no.1
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• pp.13-19
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• 2014

In this paper, we introduce a real-time method to render a 3D scene using image-based lighting. Previous approaches for image-based lighting focused on diffuse reflection and mirror-like specular reflection. In this paper, we provide a simple preprocessing approach to efficiently approximate Phong reflection model, which has been used for computer graphics applications for several decades. For diffuse reflection, we generate a texture map for diffuse reflection by integrating the source image in preprocessing step, similarly to the previous approaches. We adopt the similar idea to produce a set of specular reflection maps for various material shininess. By doing this, we can render a dynamic scene without high computational complexity or numerous texture map access.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.739-741
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• 2005

컴퓨터 게임 지리정보시스템(GIS), 가상현실 분야 등에서 환경 표현의 기반이 되는 지형 렌더링 기술은 매우 중요하다. 최근 LIDAR와 같은 3D 스캐닝 기술은 보다 정밀하고 정확한 지형 데이터를 제공한다. 하지만, 실시간 렌더링을 위해 사용되는 대부분의 방법들이 DEM이나 DTED와 같은 정규격자(uniform grid) 데이터에 최적화 되어 있기 때문에, LIDAR 데이터와 같은 비정규 데이터에는 적합하지 않다. 또한 방대한 LIDAR 데이터는 일반 PC에서 처리가 쉽지 않다. 본 논문에서는 대용량 비정규 데이터에서의 빠르고 효율적인 렌더링 방법을 제안한다. 샘플 데이터의 공간적 분포에 따라 정규격자를 생성하고, 이 격자에 맞도록 LIDAR 데이터를 재샘플링(resampling)하여 DTED와 같은 형태로 변환한다. 기하 재구성된 데이터에 연속적인 상세단계(CLOD)기반의 쿼드트리 알고리듬을 적용하여 지형을 효율적으로 렌더링한다.

• Journal of computational fluids engineering
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• v.9 no.2
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• pp.1-10
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• 2004

In the present study, a post-processing program is developed for 3D data visualization and analysis. Because the graphical user interface(GUI) of the program is based on Qt-library while all the graphic rendering is performed with OpenGL library, the program runs on not only MS Windows but also UNU and Linux systems without modifying source code. The structure of the program is designed according to the object-oriented programming(OOP) concept so that it has extensibility, reusability, and easiness compared to those by procedural programming. The program is organized as modules by classes, and these classes are made to function through inheritance and cooperation which is an important and valuable concept of object-oriented programming. The major functions realized so far which include mesh plot, contour plot, vector plot, streamline plot, and boundary plot are demonstrated and the relevant algorithms are described.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.422-425
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• 2004

This paper develops an octree-based algorithm for machining simulation. Most commercial machining simulators are based on the Z map model, which has several limitations in terms of achieving a high level of precision in five-axis machining simulation. Octree representation being a three-dimensional (3D) decomposition method, an octree-based algorithm is expected to be able to overcome such limitations. With the octree model, storage requirement is reduced. Moreover, recursive subdivision is processed in the boundaries, which reduces useless computations. The supersampling method is the most common form of antialiasing and is typically used with polygon mesh rendering in computer graphics. The supersampling technique is being used to advance the efficiency of the octree algorithm..

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.346-349
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• 1995

In this paperwe develop a real-time simulator for direct drive cooperative robot by using OpenGL in a Windows NT based system. This simulator is composed of 2 parts, a display part and an interface part. In the display part the robot is modelled and rendered in 3D space. To do this OpenGL, a kind of graphic library, is used for rendering and animating robots and kinematics gives the information of the current robot configuration. The control and the feedback data are sent and received via the interface part. In real time simulation interfacing part needs fast data transfer rate and good nosic immunity. In experiment we have simulated 2-link direct drive cooperative robots using the trajectory tracking algorithm proposed in reference.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.517-519
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• 2011

본 논문에서는 DIBR(Depth image-based rendering)을 통해 생성되는 3D 영상의 홀을 고품질로 채우는 방법을 제안한다. 이를 위해, 생성된 영상의 깊이도를 고려한 희소성(Sparsity) 기반의 인페인팅 알고리즘을 홀 채우기에 적용하였다. 본 논문에서 제안하는 알고리즘은 홀 주변의 전경 텍스쳐를 제외한 배경 텍스쳐 정보만을 이용하기 때문에, 홀 채우기 시 전경 텍스쳐와 배경 텍스쳐가 혼합되는 문제점이 발생하지 않는다. 또한 희소성 기반의 인페인팅을 이용하기 때문에 에지 정보를 활용한 고품질의 홀 채우기가 가능하다. 본 논문에서 제안하는 알고리즘과 기존의 홀 채우기 알고리즘과의 주관적 화질 비교 결과, 본 논문에서 제안하는 알고리즘의 우수성을 확인할 수 있었다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.569-574
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• 2001

인터넷상에서 가상현실을 표현하기 위한 그래픽스 포맷 표준화가 활발히 진행되고 있다. Virtual Reality Modeling Language 97 (VRML 97)은 이러한 표준화 노력으로 공인된 최근의 한 산물이며, 현재는 Web3D 컨소시움에서 VRML 확장 노드들을 추가하고 XML 문서 형식을 취하는 방향으로 VRML 97을 향상시킨 표준 포맷으로 발전시키기 위한 장을 마련하고 있다. VRML 확장을 위해 일반적으로 요구되는 중요한 요소 중 하나가 교화질의 이미지를 빠르게 얻는 것이다. 영상기반렌더링(Image-Based Rendering (IBR)) 기법은 이를 위한 좋은 방법 중 하나로, 우리는 이런 기능을 VRML에서 사용할 수 있는 VRML 확장 형태로 개발된 도구에 의해 데이터를 만들고 이를 지원하도록 VRML 브라우저를 수정하여, VRML 확장으로써의 IBR 기법의 유용성을 보이고자 한다.

• Journal of Korea Multimedia Society
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• v.7 no.12
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• pp.1700-1707
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• 2004

Nowaday, market size of digital image in world around is looks to rapidly growth. For this, Texture mapping has traditionally been used to add realism to computer graphics images. Therefore to make our image realistic, we need to give the various kind of objects material parameter and environment lighting. To present the completed marble we use passing back algorithm and combination with channel of a material. In experimental result of this paper that application by passing back algorithm and varying the parameter such as scale, period, distortion, octaves of noise make showing the superiority of optimized rendering of spheres and perfect another marble effects.

• Journal of Korea Multimedia Society
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• v.7 no.12
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• pp.1729-1736
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• 2004

This paper proposes an efficient collision detection method in the dynamic spatial subdivisions for the MMORPG engine which requires realtime interactions. An octree is a suitable structure for static scenes or terrain processing. An octree spatial subdivision enhances rendering speed of scenes. Current spatial subdivisions tend to be highly optimized for efficient traversal, but are difficult to update quickly for a changing geometry. When an object moves to the outside extent for the spatial subdivisions, the acceleration structure would normally have to be rebuilt. The OSP based on a tree is used to divide dynamically wide outside which is the subject of 3D MMORPG. TBV does not reconstruct all tree nodes of OSP and has reduced rebuilding times by TBV information of a target node. A collision detection is restricted to those objects contained in the visibility range of sight by using the information established in TBV. We applied the HBV and ray tracing for an efficient collision detection.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2008.10a
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• pp.192-192
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• 2008