• Proceedings of the Korea Multimedia Society Conference
• /
• 2003.05b
• /
• pp.464-467
• /
• 2003

본 논문에서는 체적 데이터에 대한 효율적인 볼륨 랜더링을 수행하기 위해서, 기존의 광선 추적 기법에 광선 보간을 통해 광선을 추적하는 기법인 IRCF를 제안한다. IRCF 과정은 이웃 화소에 대해 광선추적을 통해서 얻은 불투명도의 정보를 이용하여 보간한 위치에서 새롭게 광선추적을 해가는 방식이다 기존의 광선 추적 랜더링의 경우 고화질의 영상을 얻지만, Volume Rendering Operations의 계샨량이 많아 랜더링 속도가 떨어져 현재 개선된 랜더링 기법들이 많이 제안되고 있는 실정이다. 본 논문은 다른 각도로의 접근하고자 하여 제안한 IRCF 과정을 통해 Volume Rendering Operations의 계샨량을 최대한 줄여 랜더링 속도를 높이고 기존 방식의 고화질 영상에 가깝게 결과를 얻을 수가 있었다. 또한, 본 논문에서는 기존의 광선 추적 기법에서 표현하는 일반적인 회전, 절단, 불투명 등 제어 효과들을 제안한 기법을 통해 비교 분석한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.662-665
• /
• 2005

본 논문에서는 체적 데이터에 대한 효율적인 볼륨 랜더링을 수행하기 위해서, 기존의 광선 추적 기법에 대해 광선 보간을 통해서 광선을 추적하는 기법인 IRCF를 제안한다. IRCF 과정은 이웃 화소에 대한 광선추적을 통해 얻은 불투명도값의 정보를 이용해 현재 광선 추적 위치와 불투명도값을 보간한 위치에서 새롭게 광선 추적을 해가는 방식이다. 기존의 고화질의 광선 추적 랜더링의 경우 Volume Rendering Operations의 계샨량이 많아 그 만큼 랜더링 속도가 떨어져 체적에 대해 다른 개선된 랜더링 기법들이 많이 제안되고 있다. 본 논문은 다른 각도로의 접근하고자 제안한 기법을 통해 Volume Rendering Operations의 계샨량을 최대한 줄임으로 랜더링 속도를 높이고 기본의 고화질 영상에 가까운 결과을 얻을 수가 있었다. 또한, 본 논문에서는 기존의 광선 추적 기법에서 표현하는 일반적인 회전, 절단, 불투명 등 제어 효과들을 제안한 기법을 통해 비교 분석한다.

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

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

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.10C
• /
• pp.921-926
• /
• 2006

The Presence of a line-of-sight(LoS) blockage can degrade the UWB positioning accuracy for two reasons. Firstly, it makes estimation of the time of arrival(ToA) of the direct path signal difficult by complicating the multipath structure of the propagation channel. Secondly, the higher dielectric constant of the LoS blocking material than that of free space introduces excess propagation delay which will bias the range estimation. In this paper, methods based on ray tracing to reduce the ranging error resulting from the second reason are Posed. We take two different approaches; a statistical approach and a map-aided method. In the statistical approach, we establish a conditional distribution of the excess propagation delay caused by LoS blockages using a ray tracing technique. The lo6wer bound of the ranging performance based on this model is estimated. Ine ray tracing method is also used for the map-aided ToA positioning approach. UWB propagation measurement data taken in an office environment is used to examine the performance of this method.

• Journal of Korea Game Society
• /
• v.13 no.3
• /
• pp.85-94
• /
• 2013

In this paper, we propose a scheme to reduce the number of shadow tests conducted during rendering of ray tracing. The shadow test is a very important process in ray tracing to generate photo-realistic images. In the rendering phase, the ray tracer determines whether to cull the shadow test based on information calculated from a shadow test conducted on the kd-tree in the preprocessing phase. In conventional rendering process, the proposed method can be used with little modification. The proposed method is suitable for a static scene, in which the geometry and light source does not change in the same manner as it does in the conventional method. The validity of the proposed scheme is verified and its performance is evaluated during cycle-accurate simulation. Through experiment results, we found that we could reduce up to 17% of the shadow test.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.992-997
• /
• 2003

Aspherical lens design method named ray reverse tracing method is introduced. Differently from the traditional design method, the ray reverse tracing method traces the shape and location of a real object by use of its virtual image. From the result, it was convinced that spherical aberration free aspherical lens could be designed by use of the ray reverse tracing method. Furthermore, it could reduce the degree of dependence of optical characteristics on designer's ability, because deformation terms and optimization can be eliminated, which has been performed in conventional lens design process.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.6 no.1
• /
• pp.7-12
• /
• 2007

The optic industry is a high value-added advanced technology industry combined with the precision machine industry and the digital electronics industry. The aspheric lens, one of optic parts, is a key technology having a significant influence on the performance of optic equipment. So this study relates to designing an aspheric lens to which a ray-tracing method is applied. In the ray-tracing method, a refractive index of material is used, which take an advantage that the location of a light source and incident angle can be fixed, unlike the ray back-tracing scheme.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.10
• /
• pp.191-198
• /
• 2003

In this study, aberration free aspherical lens design method named ray reverse tracing method is introduced. Differently from the traditional design method, the ray reverse tracing method traces the shape and location of a real object by use of its virtual image. From the result, especially spherical aberration free aspherical lens could be designed by use of the ray reverse tracing method. Furthermore, it could reduce the degree of dependence of optical characteristics on designer's ability, because deformation terms and optimization can be eliminated, which has been performed in conventional lens design process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.6
• /
• pp.688-697
• /
• 2008

In this paper, an analysis method for indoor optical wireless channel properties based on photon model is presented for characterization of communication environment. In contrast to radio waves, optical waves have very short wave-lengths and very high frequencies, so that material properties become important. Channel models including diffuse reflections and absorption effects due to material surface textures make conventional electromagnetic wave analysis methods based on ray tracing consume enormous time. To overcome these problems, an analysis method using photon model is presented that approximates light intensity by a density of photons. The photon model ensures that simulation time is within a predictable limit.