• Journal of KIISE:Computer Systems and Theory
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• v.28 no.4
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• pp.181-187
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• 2001

본 논문에서는 3D 텍스쳐 매핑 하드웨어(texture mapping hardware)하에서 OpenGL를 이용하여 빠른 추출(classification) 및 음영처리(shading)를 가능하게 하는 직접 볼륨 렌더링(direct volume rendering) 방법을 제안한다. 추출과정을 위해 lookup table을 통해서 볼륨 데이터의 밀도값(density)으로부터 불투명도(opacity)값을 얻어내고, 법선 벡터 블렌딩(normal blending)방법을 제안하여 볼륨 크기에 상관없이 최종 이미지에서만 음영 처리 연산을 수행한다. 본 논문에서 제시된 볼륨 렌더링의 전과정이 그래픽스 하드웨어(graphics hardware)에서 이뤄지면, 음영처리 연산의 복잡도 감소로 인하여 상호 대화적인 볼륨 렌더링이 가능하다.

• Journal of Korea Multimedia Society
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• v.11 no.5
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• pp.623-632
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• 2008

In this paper, we used the color transfer function and the opacity transfer function for the internal 3D object visualization of an image volume data. In transfer function, creating values of between boundaries generally is ambiguous. We concentrated to extract boundary features for segmenting the visual volume rendering objects. Consequently we extracted an image gradient feature in spatial domain and created a multi-dimensional transfer function according to the GPU efficient improvement. Finally using these functions we obtained a good research result as an implementing object boundary visualization of the graphic hardware based 3D texture mapping.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.313-315
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• 2010

In this paper, we describe research results of developing hardware rasterizer that is applicable to mobile 3D graphics system, designed in SIMD architecture and verified in FPGA. Tile-based scan conversion unit is designed like SIMD architecture running four tiles simultaneously and each tile traverses pixels hierarchical in 3-level so that visiting counts is minimized. As experimental results, $8{\times}8$ is the most efficient size of tile and the last step of tile traversing is performed on $2{\times}2$ sized subtile. The rasterizer supports flat shading and gouraud shading and texture mapper supports affine mapping and perspective corrected mapping. Also, texture mapper supports point sampling mode and bilinear interpolating sampling mode and two types of wrapping modes and various blending modes. The rasterzer operates as 120Mhz on xilinx vertex4 $l{\times}100$ device. To easy verification, texture memory and frame buffer are generated as block rom and block ram.

• Journal of the Korea Computer Graphics Society
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• v.11 no.1
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• pp.40-49
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• 2005

Several optimization techniques have been proposed for volume ray casting, but these cannot achieve real-time frame rates. In addition, it is difficult to apply them to some applications that require perspective projection. Recently, hardware-based methods using 3D texture mapping are being used for real-time volume rendering. Although rendering speed approaches real time, the larger volumes require more swapping of volume bricks for the limited texture memory. Also, image quality deteriorates compared with that of conventional volume ray casting. In this paper, we propose a data structure for real-time volume ray casting named PERM (Precomputed dEnsity and gRadient Map). The PERM stores interpolated density and gradient vector for quantized cells. Since the information requiring time-consuming computations is stored in the PERM, our method can ensure interactive frame rates on a consumer PC platform. Our method normally produces high-quality images because it is based on conventional volume ray casting.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.712-714
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• 2002

현재 3차원 컴퓨터 그래픽 가속기에서 텍스쳐 매핑과 같은 실감기법을 처리해 주기 위해서는 넓은 대역폭과 많은 메모리를 필요로 한다. 또한 PDA와 같은 차세대 mobile 응용분야에서는 점차적으로 3차원 그래픽의 지원이 요구되고 있는 추세이다. 이를 mobile 환경에서 지원하기 위해서는 낮은 소비 전력 및 적은 메모리, 그리고 하드웨어 비용 등의 제약 요건이 따른다. 그러나 이러한 제약 조건에도 불구하고, mobile 환경에 적합한 3차원 그래픽 하드웨어의 연구는 필수적이다. 본 논문에서는 Windows CE 기반의 mobile 환경에서 Direct3D의 압축 텍스쳐 데이터를 효율적으로 처리하는 하드웨어를 제시한다. 이는 1 cycle에 2개 texel을 처리할 수 있으며, 작은 2-level cache를 사용하여 대역폭을 효과적으로 줄였다.

• Journal of the Korea Computer Graphics Society
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• v.7 no.2
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• pp.21-28
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• 2001

As a result of the recent explosive growth of scientific data, extremely large volume datasets have become increasingly commonplace. While several texture-based volume rendering algorithms have been proposed, most of them focused on volumes smaller than the hardware's available texture memory. This paper presents a new parallel volume rendering scheme for very large static and time-varying data on a multipipe system architecture. Our scheme subdivides large volumes dynamically into smaller bricks, and assigns them adaptively to graphics pipes to minimize the costs of texture swapping. With the new method, Phong shaded images can be easily created by computing the gradients on the fly and using the color matrix feature of OpenGL. We report experimental results on an SGI Onyx2 for the various large datasets.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.299-302
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• 2000

의료영상의 크기가 커짐에 따라 처리해야 할 데이터량이 많아졌다. 또한 점점 더 많은 사람들이 빠른 3차원 가시화 결과를 기대한다. 하지만 이전에 제시된 많은 방법들은 실시간 응답 결과를 기대하기는 힘들다. 본 논문은 하드웨어를 이용하여 의료영상을 빠른 속도로 3차원 가시화하는 방법과 그 구현 결과에 대해 기술한다. 구현에 있어 자바를 이용함으로써 플랫폼 독립적이며 OpenGL을 기반으로 한 자바 3D API를 사용함으로써 쉽고 빠르게 3차원 가시화 결과를 디스플레이할 수 있다.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.360-370
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• 2004

Adaptive mesh refinement(AMR) is one of the popular computational simulation techniques used in various scientific and engineering fields. Although AMR data is organized in a hierarchical multi-resolution data structure, traditional volume visualization algorithms such as ray-casting and splatting cannot handle the form without converting it to a sophisticated data structure. In this paper, we present a hierarchical multi-resolution splatting technique using k-d trees and octrees for AMR data that is suitable for implementation on the latest consumer PC graphics hardware. We describe a graphical user interface to set transfer function and viewing / rendering parameters interactively. Experimental results obtained on a general purpose PC equipped with an nVIDIA GeForce3 card are presented to demonstrate that the proposed techniques can interactively render AMR data(over 20 frames per second). Our scheme can easily be applied to parallel rendering of time-varying AMR data.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.3
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• pp.444-449
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• 2009

With the advance of high performance computing hardware, many applications have been emerging which exploit real-time computer graphics capabilities. This paper is concerned with an effective realization method for reflection effect for the situations in which moving pictures are played in 3D computer graphics modeling world. The method determines in an geometric way the locations of the projection plan into which the playing areas of moving pictures are mapped, and then realizes the reflection effect with texture mapping. Compared with the traditional stencil buffer-based reflection method, the processing time of the proposed method does not significantly deteriorate for the models with moving pictures and reflection surfaces, and its throughput was improved by 30% at minimum and 127% at maximum for the models used in the comparative studies.