T. Nishita, T. Sirai, K. Tadamura, and E. Nakamae. Display of the Earth taking into account atmospheric scattering. In Proc. SIGGRAPH 1993.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....the integration should take place over the point spread function centered on a given image pixel, but for relatively long focal lengths the added accuracy is almost never worth the computational e ort. For special cases where the volume is represented as cylindrical rings [95] or spherical shells [83] the integration over rays can be accelerated. When the density eld is de ned implicitly in terms of primitives such as Gaussian blobs, constructing lookup tables can help deliver additional speed [110] Faster and more sophisticated methods of volume rendering have also been developed. One ....

T. Nishita, T. Sirai, K. Tadamura, and E. Nakamae. Display of the earth taking into account atmospheric scattering. In Proc. ACM SIGGRAPH 1993.

....However, realistic rendering of water scenes requires the transport of light within the water body to be properly handled. Due its complexity, when considering light transport in water strong simplifications are usually made (single scattering, isotropy, homogeneous media. Nishita et al. [Nishi93a] have studied the colour of sea surface as viewed from outer space; they include in their model the scattering due to water molecules, but they make an analytic quasisingle scattering approximation. Premoze et al. Premo00a] have also considered the problem of light transport, but they have ....

Nishita, T., Sirai, T., Tadamura, K., Nakamae, E.: Display of the Earth Taking into Account Atmospheric Scattering, Computer Graphics Annual Conferences Series (SIGGRAPH'93), pp.175-182, 1993.

....3) and computer graphics [188, 198] The algorithm to compute the BDF is based on the linear transport theory and uses a Monte Carlo sampling scheme. The model explicitly evaluates the reflection and transmission of light at media boundaries, like in the ocean model proposed by Nishita et al. [171]. It assumes that the reflected radiance from a surface has two components. One arises due to surface reflectance and the other due to subsurface volume scattering. It also assumes that the transmitted radiance has two components. One represents the amount of light transmitted through the layer ....

Nishita, T., Sirai, T., Tadamura, K., and Nakamae, E. Display of the earth taking into account atmospheric scattering. In SIGGRAPH Proceedings, Annual Conference Series (August 1993), pp. 175--182. 198

....I ab (#) is given by I ab (#) I 0 (#) exp( #(P a , P b , #) 3.4) where # is the optical depth #(a, b, #) # b a # ex (#)#(s)ds (3.5) 26 b P P c P a Eyepoint P Sunlight medium Dispersive f Figure 3.2: Geometry of light traveling through a dispersive medium. After [33]. #(s) is the density of the medium at s. I sc is given by I sc (#) I sun (#) # P b Pa # sc (#, #) exp( #(P c , l, #) #(l, P a , #) dl (3.6) When the resulting I(#) has been calculated, it must typically be converted to an RGB triplet [38] 29] 3] This can be done by rst ....

....2 1) 2 # 4 N (1 cos 2 (#) 3. 11) Although N and n vary with temperature and pressure, # ex and # sc are often assumed to depend only on # and on # and # respectively [36] For computer graphics purposes, this does not seem to cause visible artefacts see, for example, the results in [33]. The 1 # 4 dependence of the scattering and extinction coe cients explains the blue color of the sky during the day and the red color at sunrise and sunset. The blue color is scattered light in the blue wavelengths and the red color is light that remains after the out scattering of the blue ....

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Nishita, T., Sirai, T., Tadamura, K., and Nakamae, E., Display of The Earth Taking into Account Atmospheric Scattering. Computer Graphics 1993, Annual SIGGRAPH conference proceedings, pp. 175182.

....systems have been implemented which integrate 3D visualization techniques with large spatial geographic information and terrain data. Some systems stress accurate rendering of global images, or accurate modeling of environmental processes, often sacrificing interactivity of the system [21, 24]. Other systems emphasize tight integration of the 3D visualization with the powerful spatial analysis capabilities of GIS [7] Systems such as VGIS place a high priority on real time, highly interactive 3D visualizations of the spatial data. Maintaining truly real time update rates in the face of ....

NISHITA, T., SIRAI, T., TADAMURA, K., and NAKAMAE, E. Display of the Earth Taking into Account Atmospheric Scattering. Proceedings of SIGGRAPH 93. In Computer Graphics Proceedings, Annual Conference Series, 1993, ACM SIGGRAPH, pp. 175--182.

....work In the area of atmospheric illumination modelling various attempts have been made to simulate the light from the sky and the Sun considering the scattering and absorption of light in the Earth s atmosphere. Of particular significance here are the works of Klassen[5] Kaneda[4] and Nishita[10]. Klassen s project used a high resolution spectral sampling technique to calculate the colour of the sky and Sun as seen from an observer fixed to the Earth s surface. Though his model atmosphere was of fixed density, it included a ground based layer of haze to simulate the effects of atmospheric ....

Nishita T, Sirai T, Tadamura K and Nakamae E, Display of the Earth taking into account atmospheric scattering, ACM Computer Graphics Proceedings, Annual Conference Series, 1993, 175-182.

....Rayleigh particle scattering. He then determines the color of each pixel in the scene by applying the change in light intensity to a precalculated sky color. The computation time using this method on a VAX 11 780 is approximately one tenth of a second per pixel for a 512 by 256 image. 9 Nishita [NISH93] describes a method to determine the color of the Earth s atmosphere as a function of position of the observer and elevation of the Sun. He discusses a spherical shell atmosphere that provides an accurate model of the sky s color. The model calculates the amount of color change caused by Rayleigh ....

....provides an accurate model of the sky s color. The model calculates the amount of color change caused by Rayleigh and Mia scattering of the incoming light. The time to calculate sky color for a 500 x 490 image ranged from just under four minutes to about 12 minutes per frame using an SGI IRIS Elan[NISH93]. Both models provide for accurate representation of the sky color. However because of the large number of calculations that must be performed to determine the color of the entire sky, the methods presented are not usable in real time applications. As Klassen states in [KLAS87] there is no ....

Nishita, Tomoyuki and others, "Display of The Earth Taking into Account Atmospheric Scattering," Computer Graphics Proceedings, Annual Conference Series 1993, ACM SIGGRAPH 1-6 August 1993, pp. 175-182.

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T. Nishita, T. Shirai, K. Tadamura, E. Nakamae, \Display of The Earth Taking into Account Atmospheric Scattering, " Proc. of SIGGRAPH'93 (1993) pp.175182.

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T. Nishita, T. Shirai, K. Tadamura, E. Nakamae, "Display of The Earth Taking into Account Atmospheric Scattering," Proc. of SIGGRAPH'93, (1993),pp. 175-182.

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T. Nishita, T. Shirai, K. Tadamura, E. Nakamae, "Display of The Earth Taking into account Atmospheric Scattering," Proc. SIGGRAPH'93, 1993, pp.175-182.

....second group model by simulating the physical process of the clouds: the numerical simulation of the fluid dynamics (Kajiya) qualitative simulation (Neyret) and dynamic simulation of the particles (Kikuchi) We have developed the following three types of cloud modeling. 1) 2D Fracltal clouds[1] We have modeled clouds to generate realistic images of the earth viewed from space. The density distribution of clouds is expressed by mapping the fractal images of the Mandelbrot set. To take into account clouds with various altitudes, multiple imaginary spheres are employed to map fractal ....

....typhoon taken from the meteorological satellite, HIMAWARI is used. Since clouds are modeled in threedimensional space, they are seen from different viewpoints and shadows can be calculated. Fig.3 in the color page shows various examples of clouds. The clouds in (a) are generated by Mondelbrot set[1]. The clouds snow in (b) d) are generated by metaballs combined with fractal[2] 3] e) is an image from the animation entitled Weather Report , that visualizes weather information[4] In this animation, the movement of a typhoon passing across Japan is visualized. f) is one image from the ....

T. Nishita, T. Shirai, T. Katsumi, E. Nakamae, "Display of The Earth Taking into Account Atmospheric Scattering," Proc. of SIGGRAPH'93, pp. 175-182 , 1993.

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T.Nishita, T. Shirai, K.Tadamura, E. Nakamae, Display of The Earth Taking into Account Atmospheric Scattering,"Proc. of SIGGRAPH'93 (1993) pp.175-182.

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T.Nishita, T. Shirai, K.Tadamura, E.Nakamae, "Display of The Earth Taking into Account Atmospheric Scattering, " Proc. of SIGGRAPH'93 (1993) pp.175-182.

.... subtle color variations, several methods of calculating sky color have been proposed [Klassen 87, Inakage 89, Kaneda 91, Tadamura 93] A method to calculate not only the color of the sky viewed from the ground but also the color of the atmosphere viewed from outer space has also been proposed [Nishita 93] The calculation of sky color, however, is time consuming as numerical integration is required to obtain the scattered light of the sun due to particles in the atmosphere. In order to make, therefore, an animation that incorporates a changing sun position and viewpoint, a great deal of time must ....

T. Nishita, T. Sirai, K. Tadamura and E. Nakamae, Display of The Earth Taking into Account Atmospheric Scattering, Computer Graphics (Proceedings of SIGGRAPH 93) (1993), pp. 175-182.

....it is impractical to create large scale clouds viewed from space. Methods for modeling a set of clusters of clouds have also been developed. Musgrave creates typhoon by the procedural approach[16] Nishita et al. have modeled clouds to generate realistic images of the earth viewed from space[27]. In both these methods, however, clouds are simply modeled by applying 2D fractals. The color and shape of clouds change depending on both the viewpoint and the position of the sun. These methods cannot simulate such kind of effects. Methods classified in the second group model clouds by ....

....of the sun changes. The color of the earth is calculated by taking into account the effect of the scattering of both sunlight and sky light due to the atmosphere by using 1 Several sites provide satellite images. For example, http: www.jwa.go.jp gms.html. the method developed by Nishita et al.[27]. In Fig. 7(a) the sun is behind the viewer, turning the color of the clouds red. In Figs. 7(b) and (c) the sun is above the clouds. And finally in Fig. 7(d) the sun is hidden behind the earth. These examples show that the optical effects can be simulated since 3D clouds are generated. These ....

T. Nishita, S. Takao, T. Katsumi, E. Nakamae, "Display of The Earth Taking into Account Atmospheric Scattering," Proc. of SIGGRAPH'93, pp. 175-182 (1993). (a) a satellite image. (b) clouds modeled by metaballs. (c) clouds viewed from different viewpoint.

....for non uniform density the numerical integration along the ray is required. For the calculation of the density distribution on the ray equation (13) can be used. The main purpose of this paper is not to discuss a shading model, so the details of the integrations are omitted. See reference [5] [7], because the basic ideas are from these references. Figure 6: Examples of metaballs. Figure 7: Examples of metaballs ( a) 1630 metaballs, b) 94 metaballs including ellipsoids) Figure 8: An example of a transparent object by using metaballs. 6 Examples Fig. 6 shows some examples. ....

T. Nishita, T. Shirai, K. Tadamura, E. Nakamae, \Display of The Earth Taking into Account Atmospheric Scattering," Computer Graphics, Vol. 27, No. 4, pp. 175-182, (1993).

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T. Nishita, T. Sirai, K. Tadamura, and E. Nakamae. Display of the Earth taking into account atmospheric scattering. In Proc. SIGGRAPH 1993.

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NISHITA T., SIRAI T., TADAMURA K., NAKA- MAE E.: Display of the earth taking into account atmospheric scattering. In Proceedings of the 20th annual conference on Computer graphics and interactive techniques (1993), ACM Press, pp. 175--182. 2, 6

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T. Nishita, T. Sirai, K. Tadamura, and E. Nakamae. Display of the earth taking into account atmospheric scattering. In Proc. ACM SIGGRAPH 1993.

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NISHITA, T., SIRAI, T., TADAMURA, K., AND NAKAMAE, E. Display of the earth taking into account atmospheric scattering. In Computer Graphics (SIGGRAPH '93 Proceedings) (1993), vol. 27.

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