• Journal of IKEEE
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• v.13 no.2
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• pp.253-259
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• 2009

In this paper, we propose a novel architecture of a general graphics shader processor without a dedicated hardware. Recently, mobile devices require the high performance graphics processor as well as the small size, low power. The proposed shader processor is a GP-GPU(General-Purpose computing on Graphics Processing Units) to execute the whole OpenGL ES 2.0 graphics pipeline by using shader instructions. It does not require the separate dedicate H/W such as rasterization on this fully programmable capability. The fully programmable 3D graphics shader processor can reduce much of the graphics hardware. The chip size of the designed shader processor is reduced 60% less than the sizes of previous processors.

• Journal of the Korea Computer Graphics Society
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• v.8 no.2
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• pp.23-29
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• 2002

In this paper, we describe an implementation technique that extends the classification and shading capabilities offered by previously reported hardware-assisted volume rendering algorithms. In designing our rendering scheme, we exploited the programmable shader technology supported by the latest consumer PC graphics hardware. Our direct volume rendering technique enables to simultaneously display up to four materials, and to dynamically control gradient magnitude to emphasize or de-emphasize surface boundaries. It can easily create lighting effects such as light source attenuation, depth cueing, and multiple light sources that were often difficult to realize in previous hardware-assisted volume rendering.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.229-232
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• 2009

In this paper, we propose a new programmable shader architecture based on an effective ALU operation. Today's mobile devices need the programmable shader processor for a three-dimensional(3D) graphics. The programmable shader processors require a lager ALU than a fixed pipeline ALU used previously. The proposed ALU architecture is able to execute two different arithmetic operations at the same time. Two instructions which need exclusive ALU operations are inserted into instruction decoders in parallel. Experimental results show the number of instruction cycles can be substantially reduced up to 40%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.9 s.351
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• pp.53-58
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• 2006

A Vertex Shader is designed to show more 3D graphics expressions, and to increase flexibility of the fixed function T&L (Transform and Lighting) engine. Design of this Shader is based on Vertex Shader 1.1 of DirectX 8.1 and OpenGL ARB. The Vertex Shader consists of four floating point ALUs for vectors operation. The previous 32bits floating point data type is replaced to 24bits floating point data type in order to design the Vertex Shader that consume low-power and occupy small area. A Xilinx Virtex2 300M gate module is used to verify behaviour of the core. The result of Synopsys synthesis shows that the proposed Vertex Shader performs 115MHz speed at the TSMC 0.13um process and it can operate as the rate of 12.5M Polygons/sec. It shows the complexity of 110,000 gates in the same process.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.38-43
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• 2007

재조명(relighting) 렌더링은 장면 내에 새로운 광원의 추가 또는 기존 광원 속성의 변경으로 인한 영상의 변화를 효율적으로 계산하는 과정을 말한다. 본 논문에서는 쉐이딩(shading) 계산에서 광원에 독립적인 파라메터를 미리 텍스쳐 이미지 형태로 캐시화하여 재조명 렌더링 과정에서의 계산량을 줄이는 방법을 사용하였다. 이러한 쉐이딩 파라메터들의 캐시 이미지들은 사용자가 카메라 시점을 바꾸고자 할 경우 새로 생성을 하여야 하는데, 이 계산에 많은 시간이 소요된다. 본 논문에서는 새로운 시점에서의 캐시 이미지들를 영상 기반 렌더링(image-based rendering) 기법을 이용하여 실시간에 구하는 방법을 제시한다. 먼저 여러 개의 지정된 카메라 시점에 대한 캐시 이미지들을 미리 생성해 둔다. 다음 원하는 시점의 캐시 이미지는 각 픽셀에 투영되는 3차원 표면점을 역시점변환(inverse viewing transform)을 통해 구하고, 이 점을 지정된 카메라 시점으로 다시 투영하여 캐시 이미지에서의 대응 픽셀을 찾는다. 대응 픽셀의 파라메터 값들을 평균하여 새 캐시 이미지에 써준다. 이 과정들은 하드웨어 그래픽 가속기의 단편 쉐이더(fragment shader)를 이용하여 실시간으로 수행된다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.20-25
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• 2009

We propose hardware architecture of floating-point square root and inverse square root arithmetic units using lookup tables. They are used for lighting engines and shader processor for 3D graphic processing. The architecture is based on Taylor series expansion and consists of lookup tables and correction units so that the size of look-up tables are reduced. It can be applied to 32 bit floating point formats of IEEE-754 and reduced 24 bit floating point formats. The square root and inverse square root arithmetic units for 32 bit and 24 bit floating format number are designed as the proposed architecture. They can operation in a single cycle, and satisfy the precision of $10^{-5}$ required by OpenGL 1.x ES. They are designed using Verilog-HDL and the RTL codes are verified using an FPGA.

• Journal of IKEEE
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• v.12 no.4
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• pp.246-254
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• 2008

This paper represents a design of a 4 way SIMD processor with multi-thread and dual phase instruction pipeline. 8 threads can be performing in round-robin order, so any hazards can’t occur. The dual phase pipeline makes a pipeline operate as two pipelines, and it can fetch maximum 4 unit instructions at once. This variable length instruction set divide into first phase and second phase instructions, and with this function, complex branch and addressing can be executed at one clock cycle. This processor reduces the code size to quarter, pull out the doubled performance improvement than normal SIMD architecture.

• Journal of Korea Multimedia Society
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• v.14 no.10
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• pp.1229-1237
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• 2011

The volume ray-casting method is one of the direct volume rendering methods that produces high-quality images as well as manipulates semi-transparent object. Although the volume ray-casting method produces high-quality image by sampling in the region of interest, its rendering speed is slow since the color acquisition process is complicated for repetitive memory reference and accumulation of sample values. Recently, the GPU-based acceleration techniques are introduced. However, they require pre-processing or additional memory. In this paper, we propose efficient point-primitive based method to overcome complicated computation of GPU ray-casting. It presents semi-transparent objects, however it does not require preprocessing and additional memory. Our method is fast since it generates point-primitives from volume dataset during sampling process and it projects the primitives onto the image plane. Also, our method can easily cope with OTF change because we can add or delete point-primitive in real-time.

• Journal of the Korea Computer Graphics Society
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• v.17 no.3
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• pp.1-7
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• 2011

Recently, various researches have been proposed to accelerate GPU-based volume ray-casting. However, those researches may cause several problems such as bottleneck of data transmission between CPU and GPU, requirement of additional video memory for hierarchical structure and increase of processing time whenever opacity transfer function changes. In this paper, we propose an efficient GPU-based empty space skipping technique to solve these problems. We store maximum density in a brick of volume dataset on a vertex element. Then we delete vertices regarded as transparent one by opacity transfer function in geometry shader. Remaining vertices are used to generate bounding boxes of non-transparent area that helps the ray to traverse efficiently. Although these vertices are independent on viewing condition they need to be reproduced when opacity transfer function changes. Our technique provides fast generation of opaque vertices for interactive processing since the generation stage of the opaque vertices is running in GPU pipeline. The rendering results of our algorithm are identical to the that of general GPU ray-casting, but the performance can be up to more than 10 times faster.

• Journal of the HCI Society of Korea
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• v.2 no.1
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• pp.25-31
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• 2007

We develop an interactive relighting renderer allowing camera view changes based on a deep-frame buffer approach. The renderer first caches the rendering parameters for a given 3D scene in an auxiliary buffer with the same size of the output image. The rendering parameters independent from light changes are selected from the shading models used for shading pixels. Next, as the user interactively edits one light at one time, the relighting renderer instantly re-shades each pixel by updating the contribution of the changed light with the shading parameters cached in the deep-frame buffer. When the camera moves, the cache values should be re-computed because the currently cached values become obsolete. We present a novel method to synthesize them quickly from the cache images of the user specified cameras by using an image-based technique. This computations are all performed on GPU to achieve real-time performance.