• The Transactions of the Korea Information Processing Society
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• v.6 no.4
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• pp.1081-1089
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• 1999

Volume data modeling is concerned with finding a mathematical function which represents the relationship implied by the 3D data. Modeling a volume data geometrically can visualize a volume data using surface graphics without voxelization. It has many merits in that it is fast and requires little memory. We proposes, a method based on wavelet transformation and tetrahedrization. we implement a prototype system based on the proposed method. Last, we evaluated the proposed method comparing it with marching cube algorithm. the evaluation results show that though the proposed method uses only 13% of the volume data, the images generated is as good as the images generated by the marching cubes algorithm.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.12
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• pp.581-586
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• 2017

This paper proposes a GPU based water surface animation and rendering technique for interactive applications such as games. On the water surface, a lot of physical phenomenon occurs including reflection and refraction depending on the viewing direction. When we represent the water surface, not only showing them in real time, but also make them adjusted automatically. In our implementation, we are able to capture the reflection and refraction through render-to-texture technique and then modify the texture coordinates for applying separate DU/DV map. Also, we make the amount of ratio between reflection and refraction change automatically based on Fresnel formula. All proposed method are implemented using OpenGL 3D graphics API.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.651-654
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• 2005

Shadows are important elements for realistic rendering of the 3D scene. Image based methods which are techniques to generate shadows are widely used because of fast calculation time. However, this algorithm has aliasing problems. PCF is a method to solve the aliasing problem. Using PCF technique, antialiased shadow boundary can be generated. However, PCF with large filter size requires more time to calculate antialiased shadow boundary. This paper introduces an improved PCF technique which generates antialiased shadow boundary similar to that of PCF. Compared with PCF, this technique can generate antialiased shadows in less time.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.11a
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• pp.77-80
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• 2018

360 VR 콘텐츠는 기존의 선형적인 일반 영상에 비해 사용자에게 더 많은 정보와 높은 몰입감을 제공할 수 있어 의학, 군사, 교육, 게임 등 다양한 분야에서 활용되고 있다. 최근에는 모바일 기기의 성능 향상과 통신기술의 발달에 힘입어 모바일 네트워크를 사용한 360 VR 콘텐츠 소비가 증가하는 추세이다. 모바일 네트워크는 대역폭이 한정적이고 가변적인 특성이 있어 이를 통해 용량이 큰 360 VR 콘텐츠 전송 시 초기 접속 지연 및 재생 끊김이 발생하여 사용자의 만족도를 감소시킬 수 있다. 이에 본 논문은 위에 언급한 문제를 해결하기 위해 360 VR 콘텐츠 전송 시 전체 요구대역폭을 감소시키고 사용자 초기 접속 속도를 향상시키는 것을 목표로, 360 VR 콘텐츠의 지오메트리 값과 사용자의 요(i.e. yaw)값을 활용하여 각도 기반으로 사용자의 현재 시점에 해당하는 타일을 확인하고 해당 타일에 높은 비트율을 할당하는 방법 및 웹 기반 전송에 대해 연구 개발하였다. 이를 위하여 웹 기반 3D 렌더링 API 인 WebVR API, HTTP Adaptive Streaming 기술의 표준 MPEG-DASH의 dash.js API를 활용하여 개발하고, 성능 확인 실험을 통해 요구대역폭 감소, 클라이언트 접속 속도 향상을 제시한다.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.2
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• pp.83-90
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• 2024

CNC tools contribute to the production of high-precision and consistent results. However, employing damaged CNC tools or utilizing compromised numerical control can lead to significant issues, including equipment damage, overheating, and system-wide errors. Typically, the assessment of external damage to CNC tools involves capturing a single viewpoint through a camera to evaluate tool wear. This study aims to enhance existing methods by using only a single manually focused Microscope camera to enable comprehensive external analysis from multiple perspectives. Applying the NeRF (Neural Radiance Fields) algorithm to images captured with a single manual focus microscope camera, we construct a 3D rendering system. Through this system, it is possible to generate scenes of areas that cannot be captured even with a fixed camera setup, thereby assisting in the analysis of exterior features. However, the NeRF model requires considerable training time, ranging from several hours to over two days. To overcome these limitations of NeRF, various subsequent models have been developed. Therefore, this study aims to compare and apply the performance of Instant NGP, Mip-NeRF, and DS-NeRF, which have garnered attention following NeRF.

• Journal of the Korea Convergence Society
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• v.4 no.4
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• pp.13-19
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• 2013

In this paper, we design and develop an educational virtual system which can experience Goguryeo tomb murals in the virtual world. Goguryeo tomb murals are well known in the world, and they are registered as a UNESCO World Heritage site by the value Acknowledged worldwide. We design an user-friendly interface for Goguryeo tome murals by Flash, and make a modelling and rendering with 3D Max. In addition, we create an educational animation with Adobe Premiere. We choose some of items such as Goguryeo tomb murals, historical sites, high-level description of periodization, Goguryeo's clothes, home, play as sub-themes, and we develop a system with detailed views and informations for the daily life of the people of Goguryeo.

• Journal of Digital Contents Society
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• v.19 no.5
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• pp.971-979
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• 2018

Currently, Virtual Reality video content is rapidly increasing in number of users due to the rapid growth of related hardware and software. Accordingly, Virtual Reality animation is also being produced in a new form by rapidly integrating with Virtual Reality technology among video contents. Currently, research on Virtual Reality animation has focused on how films are produced and how they are directed, and no research has been done to organize the pipeline for efficient VR animation production. Therefore, this study drew the characteristics of the pre-render VR animation pipeline by comparing it with the production pipeline of the existing 3D animation to produce the VR animation efficiently. Through this, we presented organic integration of production and post production processes suitable for the production of VR animations and reduced rendering time using Render Pass for efficient production.

• Journal of KIISE
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• v.43 no.4
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• pp.419-429
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• 2016

Generating a 3D surface model from coronary artery segmentation helps to not only improve the rendering efficiency but also the diagnostic accuracy by providing physiological informations such as fractional flow reserve using computational fluid dynamics (CFD). This paper proposes a method to generate a triangular surface mesh using vessel structure information acquired with coronary artery segmentation. The marching cube algorithm is a typical method for generating a triangular surface mesh from a segmentation result as bit mask. But it is difficult for methods based on marching cube algorithm to express the lumen of thin, small and winding vessels because the algorithm only works in a three-dimensional (3D) discrete space. The proposed method generates a more accurate triangular surface mesh for each singular vessel using vessel centerlines, normal vectors and lumen diameters estimated during the process of coronary artery segmentation as the input. Then, the meshes that are overlapped due to branching are processed by mesh merging and merged into a coronary mesh.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.28-32
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• 2008

The displays and the interactive interfaces are important factors to enhance immersion in the VR experience pavilion. In the VR experience pavilion displaying 3D Virtual environment, it is difficult to have multi-display with single viewpoint because of the field of view. Also it costs a lot to construct a large size display. The interaction device between user and VR environment necessary to immersion has used mainly the touchscreens with the restricted display area or the button-based input devices so far. In this paper, we suggest a method for constructing extensible multi-display which are showing VR environment in realtime and a method for interaction using a ZA Sensor which is wireless and guarantees the user's unrestricted movement. The proposed method can make a VR experience pavilion more immersive at less cost.

• Journal of Internet Computing and Services
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• v.16 no.5
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• pp.49-57
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• 2015

In this Paper, we introduce an efficient on-line software service using an application customized graphic offloading library. The software service based on graphic offloading provides high-end software, like a 3D graphic design tool, as an on-line software service through using a client graphic rendering. When software is executed on server, its graphic works are handled by a client's GPU, while its data works are handled by a server's CPU. To improve the performance, we apply an asynchronous transmission channel scheme to our developed basic graphic offloading engine. Also, we add optimized common module and application specific module to our engine. To do that, we introduce how to implement the application specific module using analyzing patterns of graphic related APIs and messages that are generated by an executed software process. Also, we propose how to design the optimized common module using server side information caching. Finally, through the performance comparison experiment, we show that improved offloading engine has the better performance than old basic offloading engine.