• Journal of Korea Game Society
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• v.7 no.3
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• pp.59-66
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• 2007

Ray tracing is one of the classical global illumination methods to generate a photo-realistic rendering image with various lighting effects such as reflection and refraction. However, there are some restrictions on real-time applications because of its computation load. In order to overcome these limitations, many researches of the ray tracing based on GPU (Graphics Processing Unit) have been presented up to now. In this paper, we implement the ray tracing algorithm by J. Purcell and combine it with two methods in order to improve the rendering performance for interactive applications. First, intersection points of the primary ray are determined efficiently using rasterization on graphics hardware. We then construct the acceleration structure of 3D objects to improve the rendering performance. There are few researches on a detail analysis of improved performance by these considerations in ray tracing rendering. We compare the rendering system with environment mapping based on GPU and implement the wireless remote rendering system. This system is useful for interactive applications such as the realtime composition, augmented reality and virtual reality.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.26.2-26.2
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• 2010

이 연구는 Ashen light 측정을 통해 전 지구 반사율을 구하는 통합적 광선 추적 모델을 구성하고 그 수치모사 성능을 검증하는데 목적을 두고 있다. 통합적 광선 추적 모델은 태양-지구-달 시스템에 대하여 태양 복사에너지의 광경로를 추적함으로써 최종적으로 저궤도 상에 존재하는 광학계에 도달하는 Ashen light과 moonshine의 조도를 수치 모사하는 기법이다. Ashen light은 구형의 태양에서 출발한 $1.626\times10^{26}W$의 에너지를 가지는 400nm에서 700nm 파장대역의 빛이 램버시안 특성을 지니는 구형의 지구에서 반사된 후 램버시안 특성을 가지는 구형의 달에서 재 반사되어 저궤도상의 광학계로 입사하는 빛이고, moonshine은 달에서 직접 반사되어 저궤도상의 광학계로 입사하는 빛이다. 통합적 광선 추적 수치 모사를 이용하여 구한 Ashen light과 moonshine의 조도는 1차 근사 해석적 방법을 이용한 계산 결과와 측정 오차 범위 이내의 오차를 보였다. 최종 연구 결과 Ashen light과 moonshine의 조도를 이용하여 구한 지구 반사율과 1차 근사 해석적 방법을 이용한 지구 반사율 계산의 결과가 유사함을 증명하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.393-394
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• 2008

컴퓨터 그래픽의 분야에서 Global illumination을 계산하는 과정은 우선 광선 추적 기법을 기반으로 한다. 가장 늦게 소개되어 사용자 층이 늘어나고 있는 photon mapping 기법도 scene rendering을 수행하기 이전에 광선 추적을 이용하여 photon의 공간적 분포를 미리 계산하는 과정을 활용한다. 본 고(稿)에서는 광학용으로 사용되는 SW를 scene rendering에 활용할 수 있는 가능성을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.54-56
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• 2018

이 논문에서는 Graphics 시스템이 점차 광선추적법(Ray-tracing) 기반으로 전환되고 있는 점과, OpenGL, Direct3D 등의 3차원 그래픽스 API가 삼각형 메시를 주로 사용하는 점에서 착안하여 크로노스 그룹의 차세대 그래픽 표준인 Vulkan API를 이용하여 광선추적기를 개발하였다. 여기에 삼각형 메시를 적용하여 성능평가를 수행하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.617-620
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• 2000

컴퓨터를 활용하여 사진영상을 얻는 기술은 여러 분야에서 많은 응용이 이루어지고 있는데, 그 중에서도 광선추적기법은 가장 많이 쓰이면서도 현실감 있는 사진영상을 얻는 음영처리 기법중의 하나이다. 하지만 영상이 복잡해짐에 따라 컴퓨터로 처리하는 시간도 그만큼 많이 소요되는데 슈퍼컴퓨터 상에서 병렬처리기법을 적용함으로써 처리시간을 상당히 줄일 수가 있다. 본 논문에서는 IBM RS/6000 SP 슈퍼컴퓨터를 활용하여 순차적 광선추적 알고리즘을 메시지 교환방식을 통한 병렬처리 기법으로 성능분석을 하고자 하였다. 실험을 위해서 슈퍼컴퓨터의 노드수를 최대 16개까지 증가시켜 가면서 복잡한 영상에 대해 병렬 광선추적 알고리즘의 성능분석을 하였고, 메시지 교환방식 중에서 블락킹 통신과 비블락킹 통신에 대해서 그 성능을 각각 비교하였다.

• Journal of the Korea Computer Graphics Society
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• v.26 no.1
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• pp.7-15
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• 2020

In the process of visualizing a point set representing a smooth manifold surface, global illumination techniques can be used to render a realistic scene with various effects of lighting. Thanks to the continuous demand for ray tracing and the development of graphics hardware, dedicated GPUs and programmable pipeline for ray tracing have been introduced in recent years. In this paper, real-time global illumination rendering is studied for a point-set model using ray-tracing GPUs. We apply the moving least-squares (MLS) method to approximate the point set to a smooth implicit surface and render it using global illumination by performing massive ray-intersection tests with the surface and generating shading effects at the intersection point. As a result, a complicated point-set scene consisting of more than 0.5M points can be generated in real-time.

• Journal of Korea Game Society
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• v.10 no.4
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• pp.73-80
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• 2010

This paper proposes an effective method to select MIP-Map level of texture images for ray-traced texture mapping. This MIP-Map level selection method requires only the total length of intersected ray. By supporting MIP-Map for texture mapping, we can reduce the texture aliasing effects, while our approach decreases rendering performance very slightly.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.8
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• pp.691-700
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• 2000

The standard volume ray-tracing, optimized with octree, needs to repeatedly traverse hierarchical structures for each ray that often leads to redundant computations. It also employs the expensive 3D interpolation for producing high quality images. In this paper, we present a new ray-casting method that efficiently computes shaded colors and opacities at resampling points by traversing octree only once. This method traverses volume data in object-order, finds resampling points on slices incrementally, and performs resampling based on 2D interpolation. While the early ray-termination, which is one of the most effective optimization techniques, is not easily combined with object-order methods, we solved this problem using a dynamic data structure in image space. Considering that our new method is easy to implement, and need little additional memory, it will be used as very effective volume method that fills the performance gap between ray-casting and shear-warping.

• Journal of The Korean Association For Science Education
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• v.24 no.6
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• pp.1189-1205
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• 2004

The purpose of this study is to understand the types of teacher and student's concept on ray-tracing and spectrum in middle school. This study suggest key-concepts that is most important to "Light" unit in the seven grades: the ray-tracing and the spectrum. We examined the types of teacher and student's concept. We selected 10 teacher and 328 students who had learned by 10 teachers in Seoul and Gyeonggi. The problems were composed with the question item regarding all ray-tracing or the spectrum. From the analysis, it was found that the types of teacher and student's concept on ray-tracing and spectrum is different. The most of teacher and student didn't understand the basic principle of image formation. In case of context about formation of image by reflection and refraction, because they don't know ray-tracing, they do not try to find the position of the image by drawing two rays. Most of them used one ray comes from the one position of the object and indicated the position of image by memorized position. Also almost there was not a case which uses a ray tracing accurately. In the case of understanding color, they didn't understand the concept of color(or spectrum) and teachers represented to students the color phenomena without explanation of principles. In the result teachers and students would learn color science by rote.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.459-465
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• 2007

In this paper, we implemented a ray-tracing simulator with a ray-launching technique and generated the propagation path of each ray in a multiple-wall indoor environment. In this simulator, we adopted two dimension ray-tracing techniques considering the reflection and penetration were dominant propagation factor in the indoor channel. From the result, we verified that this ray-tracing simulator shows the similar path pattern and delay distribution with the experiment results of the previous research. Especially, impulse responses of the ray were corresponding to reference result in non-line of sight of multiple-wall indoor environment. Furthermore, we confirmed that channel profiles having respectively different departure angle 1 degree to 7 degree were similar between them.