• Journal of the Korea Computer Graphics Society
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• v.4 no.1
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• pp.79-88
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• 1998

Till now there are several rendering models for water and simulating other fluids and their dynamics. Especially in order to generate a curved surface of flexible objects such as liquid and snow, the implicit metaball formulation is widely used in favor of its simplicity and flexibility. This paper proposes one excellent method for generating water droplets, which would be deformed in gravitation field. In previous works, a water droplet was simply represented by approximated curved surfaces of a symmetric metaball. Thus the final result of the rendered water droplet was far from a realistic droplet, because they do not consider the gravitational effect in droplets. We propose a new metaball model for rendering water droplets placed on an arbitrary surface considering the gravitation and friction between droplet and plate. Our new metaball model uses a new vector field isosurface function to control the basic scalar metaball with respect to the norm of gravitational force. In several experiments, we could render a photo-realistic water droplets with natural-looking shadows by applying ray-tracing.

• 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.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.577-579
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• 1999

컴퓨터 그래픽의 모델링에 있어서 메타볼은 인체를 모델링하기에 매우 적합한 모델링 요소로서 사용되어 왔다. 메타볼을 랜더링하는 방법으로서는 광추적기법(ray-tracing)이나, 메타볼을 다각형화하여 다각형랜더링가속기를 이용하는 것이 있는데, 전자는 높은 계산량으로 인해서 실시간으로 랜더링하기 어려운 문제가 있고, 후자인 경우에는 모델링 과정에서 메타볼로 구성된 모델로부터 다각형들을 추출하여 이를 랜더링 시에는 랜더링 가속기를 이용해서 실시간으로 랜더링 할 수 있는 장점이 있지만, 다각형을 추출하는 과정이 높은 계산량과 많은 메모리를 필요로 하므로 랜더링 시 모델의 특성이 변화하는 경우마다 많은 계산량을 필요로 하는 다각형화를 재 수행해야 하므로 실시간 랜더링이 어려운 문제가 있다. 메타볼로 구성된 모델로부터 다각형을 추출하는 방법으로 많은 연구가 진행되었지만, 이들 대부분이 많은 메모리와 높은 계산량을 요구하고, 다각형화를 가속화기위한 병렬화가 어려운 문제점이 있다. 이로 인해서, 본 논문에서는 다음과 같이 두 가지 특징이 잇는 메타볼 다각형화 알고리즘에 대해서 제안하고자 한다. 첫째로 기존의 방법에 비해서 적은 메모리를 사용한다. 둘째로 높은 병렬화로 하여금 계산량의 문제를 해결하고자 한다.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.307-318
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• 2009

Modeling and rendering of atmospheric phenomena such as clouds is one of most difficult research themes in the field of computer graphics, mainly due to its complexity, huge volume, ubiquitousness, etc. In this paper, we represent a system for real-time modeling and rendering of clouds, mainly aiming at the computer games and flight simulation applications. Our implementation generates various kinds of clouds including cirrus, stratus, and cumulus, through intuitive real-timeuser interactions. Then, additional details are automatically attached to them, using our own methods based on meta-balls or hierarchical spherical particles. After processing multiple scattering and anisotropic scattering, resulting particles are rendered into billboards, to finally achieve real-time processing.