Abstract from Some of Our Papers (5/6)
Computer Graphics and Imaging'99
IEEE Trans. on Mag., Vol. 34, No. 3 (1998)
Pacific Graphics'98
"Interactive Rendering of Atmospheric Scattering Effects Using Graphics Hardware"
by Yoshinori Dobashi, Tomoyuki Nishita , T. Yamamoto
Abstract
To create realistic imges using computer graphics, an important element to consider is atmosphieric scattering, that is, the phenomenon by which light is scattered by small particles in the air. This effect is the cause of the light beams produced by spotlights, shafts of light, foggy scenes, the bluish appearance of the earth's atomosphere, and so on.
This paper proposes a fast method for rendering the atmospheric scattering effects based on actual physical phenomena. In the proposed method, look-up tables are prepared to store the intensities of the scatterd light, and these are then used as textures. Realistic images are then created at interactive rates by making use of graphics hardware.
Additional information
"An Accurate, Fast Method Using Graphics Hardware for Rendering
Shafts of Light"
by Yoshinori Dobashi, Tomoyuki Nishita, T. Yamamoto (in Japanese)
Abstract
An important element in enhancing the reality of computer graphics is the effect of atmospheric scattering. This effect create shafts of light when atmospheric particles are illuminated.
We have developed an accurate and fast mehod for displaying shafts of light prodused by studio spotlights.
To calculate the intensity of the light reaching the viewpoint, multiple sime-transparent planes are placed in front of the viewpoint. The intensities of these planes are set to the intensities of the light reaching the viewpoint.
The shafts of light are displayed based on the intensities of the planes. These processes are accelerate by graphics hardware, using, in particular, color blending, texture mapping, shadow mapping, and multi-texturing functions.
The proposed method renders the shafts of light very quickly, making it useful for designing lighting effects in sudios, on stages, and so on.
Additional information
"Animation of Clouds Using Cellular Automaton"
by Yoshinori Dobashi, Tomoyuki Nishita, T. OkitaAbstract
Recently, computer graphics have been used to simulate natural phenomena, such as clouds, fire, and ocean waves. This paper focuses on the evolution of clouds and proposes a simulation method for dynamic clouds. The method makes use of the cellular automaton for calculating the density distribution of clouds which varies over time. By using the cellular automaton, the distribution can be obtained with only a small amount of computation since the dynamics of clouds are expressed by several simple transition rules. The proposed method is applied to animations of outdoor scenes to demonstrate its usefulness.
Key Words:
clouds, animatoin, cellular automaton, natural phenomena, simulation
Additional information
pdf(157KB)
"Using metaballs to modeling and animate clouds from setellite
images "
by Y.Dobashi, T. Nishita, H. Yamashita, T. Okita
Abstract
We propose modeling that uses metaballs to create realistic clouds from
satellite images. The method is intended for space flight simulators,
visualization of the weather information, and simulation of surveys of the
earth. The density distribution inside the clouds is defined by a set of
metaballs. The parameters (center positions, radii, and density values) are
automatically determined so that the synthesized image is similar to the
satellite image. We also propose an animation method for clouds generated by
a sequence of satellite images taken at a given interval. We give several
examples of clouds generated from satellite images of typhoons passing
through Japan.
Key Words:
Additional information
"An Interactive Lighting Design System Integrating Forward and Inverse Approach"
by Y.Dobashi, K.Kaneda, H.Nakatani, H.Yamashita (in japanese)
Abstract
Recently, computer graphics has been one of indispensable techniques
for interior lighting design.
Using computer graphics, lighting effects design can be visualized in
advance. Traditionally either a forward or an inverse approach is used
for the lighting design. Besides, it is very difficult to interactively
design lighting effects under intereflective environment since
high computational cost is required for obtaining the results.
This paper proposes a new system for an interactive lighting design,
integrating both the forward and the inverse approaches. The proposed
system makes it possible to design lighting effects from both the
forward and inverse points of views. Using he proposed system,
users can design lighting effects efficiently and ituitively.
Key Words:
Additional information
"A Fast Volume Rendering Method for Time-Varying 3-D Scalar Field Visualization Using Orthonormal Wavelets"
by Y.Dobashi, C.Vlatko, K. Kaneda,
H. Yamashita,
T. Nishita
Abstract
Animation of a time varying 3-D scalar field distribution requires generation of a set of images at a sampled time intervals i.e. frames. Although, volume rendering method can be very advantageous for such 3-D scalar field visualizations, in case of animation, the computation time needed for the generation of the entire set of images can be considerably long. To address this problem, this paper proposes a fast volume rendering method which utilizes orthonormal wavelets. The coherency between frames, in the proposed method, is eliminated by expanding the scalar field into a series of wavelets. Application of the proposed method for time-varying eddy-current density distribution inside an aluminum plate (TEAM Workshop Problem 7) is given.
Key Words:
Sientific visualization, Volume rendering, Wavelet transform, Eddy currents.
Additional information
pdf(506KB)
"Modeling of Clouds from Satellite Images Using Metaballs"
by Y. Dobashi, T.Nishita,
H.Yamashita, T. OkitaAbstract
This paper proposes an image-based modeling of clouds where realistic clouds are created from satellite images using metaballs. The intention of the paper is for applications to space flight simulators, the visualization of the weather information, and the simulation of surveys of the earth. In the proposed method, the density distribution inside the clouds is defined by a set of metaballs. Parameters of metaballs, such as center positions, radii, and density values, are automatically determined so that a synthesized image of clouds modeled by using metaballs is similar to the original satellite image. We also propose an animation method for clouds generated by a sequence of satellite images taken at some interval. The usefulness of the proposed method is demonstrated by several examples of clouds generated from satellite images of typhoons passing through Japan.
Key Words:
Additional information
"A Quick Rendering Method for Outdoor Scenes Using Sky Light Luminance Functions Expressed with Basis Functions"
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