• Journal of KIISE:Computer Systems and Theory
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• v.33 no.10
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• pp.759-767
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• 2006

The level-of-detail (LoD), which is a method of reducing polygons on mesh, is one of the most fundamental techniques in real-time rendering. In this paper, we propose a novel level-of-detail technique applied to the virtual character's motion (Motion LoD). The movement of a virtual character can be defined as the transformation of each joint and it's relation to the mesh. The basic idea of the proposed 'Motion LoD' method is to reduce number of joints in an articulated figure and minimize the error between original and simplified motion. For the motion optimization, we propose an error estimation method and a linear system reconstructed from this error estimation for a fast optimization. The proposed motion simplification method is effectively useful for motion editing and real-time crowd animation.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.1
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• pp.102-108
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• 2010

With gradual growth of digital image contents industry connected with computer graphics technology, users require high-quality animations similar to real world and want to observe the type of fishes or their swimming types through cyber aquarium and fish encyclopedia. This study designed and developed fish growth process system to express natural and dynamic movement of fish, which is the critical in expressing submarine environment. This system proposes new mopping technique not presented in existing mopping studies as well as simulation using algorithm that newly supplemented existing fish swimming types. In addition, disease infection status is realistically expressed, which may occur depending on environmental factors during their growth process. With comprehensive fish studies, different from existing fish studies, this study examines the overall features of fish with realistic simulation.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.17-29
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• 2008

In Computer Graphics, fluid dynamics is used for animating and expressing the various special effects of water. As the hardware performance is getting higher, the several algorithms for fluid dynamics become to be executed in real time. However, it still requires a lot of computational time to get the realistic and detailed results. Therefore, there are many researches on the techniques of balancing between performance and quality. It must give priority to the executive performance preserving the visual reality even though sacrificing the physical reality, specially in applications with the game context which need to express the interaction between 3D objects and the surface of the water such as the sea or a lake. In this paper, we propose a method for the realtime animation of interactions between 3D objects and the surface of the water using the linear convolution of height fields and the bounding spheres of object.

• 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.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.105-113
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• 2020

The development and application of cultural technologies(CT) are expected to lead to create various service scenarios and business models. Considering the wide range of application and extensibility of CT, it is necessary to design multidimensional evaluation methods for priority of the support of R&D budgets. The method should include the various evaluation criteria such as economic feasibility and user benefit of service made by a cultural technology. Our research addresses priority decision for fosterage of cultural technologies using fuzzy TOPSIS. Seven evaluation attributes are used to compare five specific technologies. Based on the results, service usefulness is the most important factor among the evaluation attributes. Also, technologies of computer graphics and UI/UX have higher priority than the others. We expect our research to help to provide guidelines for selection of promising cultural technologies which foster the culture and contents industry.

• Journal of Korea Multimedia Society
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• v.14 no.8
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• pp.1082-1093
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• 2011

Traditional rendering of cartoon character cannot revive the feeling of concept drawings properly. In this paper, we propose capture technology to get toon shading model from the concept drawings and with this technique, we provide a new novel system to render 3D cartoon character. Benefits of this system is to cartoonize the 3D character according to saliency to emphasize the form of 3D character and further support the sketch-based user interface for artists to edit shading by post-production. For this, we generate texture automatically by RGB color sorting algorithm to analyze color distribution and rates of selected region. In the cartoon rendering process, we use saliency as a measure to determine visual importance of each area of 3d mesh and we provide a novel cartoon rendering algorithm based on the saliency of 3D mesh. For the fine adjustments of shading style, we propose a user interface that allow the artists to freely add and delete shading to a 3D model. Finally, this paper shows the usefulness of the proposed system through user evaluation.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.4
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• pp.353-361
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• 2000

In Computer Graphics, to select the element for modeling is very important in aspect of real-time processing of photorealistic images. Especially in modeling of informal objects, the criteria of choice are such as the minimum number of data, the easy rendering technique, and the expansibility. The metaball model which is one of the methods for modeling the implicit surface is excellent in modeling the complicated surface with a few data. However, a greater number of data are required for modeling objects that consist of planar surfaces with metaballs than with polygons. In this paper, we propose the new skeletal element, metacube which has the merits of metaball and improves the modeling ability of informal objects containing planar surfaces. A metacube has two parameters to change freely its shape from the cube to the sphere and can easily do the modeling of objects with curved surfaces and plane surfaces.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.2
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• pp.189-198
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• 2004

As display devices evolve, computer-based work environments are also becoming better suited to actual application tasks. This paper discusses the development of an architectural design system using the virtual table, which is a table-type projection system. It consists of the interactive VR modeler, the hybrid tracker and the architectural interpreter. The interactive VR modeler offers visual and tactile guide such as grid interaction, a tangible transparent prop and reference objects, so that a user can design architectural 3D models more easily and intuitively on the virtual table. The hybrid tracker includes two types of tracking methods for viewpoint according to the user's view and hand interaction: namely, vision-based tracking and magnetic tracking. The architectural interpreter automatically transforms simple 3D masses into a basic construction form that has architectural knowledge. The proposed system has advantage in the sense that it is suitable for collaboration among several users, allowing them to view graphical objects in stereoscopic view with direct 3D manipulation. Thus, it can be effectively used for architectural simulation and user-participated design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2698-2706
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• 2010

Most tiled display systems supported a public workspace model where multiple users share the contents and work together on a large public screen. In this research, we developed ICE Display Framework, designed for supporting easy construction of tiled display applications allowing mixed-focus collaboration. Mixed-focus collaboration is a model that allows a number of users to work together as a group or individually on the large workspace. ICE Framework allows users to add personal contents on the tiled display without interrupting other users as well as to put shared works. In this paper, we compare ICE framework with previous research and explain the detail implementation. Then, we introduce the applications built with this framework and discuss the evaluation and analysis of the performance of the new framework.

• Journal of Korea Game Society
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• v.7 no.2
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• pp.11-20
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• 2007

This paper proposes a real-time simulation technique for thin shells undergoing large deformation. Shells are thin objects such as leaves and papers that can be abstracted as 2D structures. Development of a satisfactory physical model that runs in real-time but produces visually convincing animation of thin shells has been remaining a challenge in computer graphics. Rather than resorting to shell theory which involves the most complex formulations in continuum mechanics, we adopt the energy functions from the discrete shells proposed by Grinspun et al. For real-time integration of the governing equation, we develop a modal warping technique for shells. This new simulation framework results from making extensions to the original modal warping technique which was developed for the simulation of 3D solids. We report experimental results, which show that the proposed method runs in real-time even for large meshes, and that it can simulate large bending and/or twisting deformations with acceptable realism.