Klassen,R.V., "Modeling the Effect of the Atmosphere on Light" , ACM Transactions on Graphics, 6(3), pp.215-237 (1987).  Home/Search   Document Not in Database   Summary   Related Articles   Check

....separable into factors containing only z and alone. In fact, longer distances tend to increase the contrast (change the shape) of the absorption spectrum, resulting in a more saturated colour for thicker materials. Participating media can also have wavelength dependent scattering distributions [4, 10], which can result in similar distance dependent spectral colour shifts. Finally, the refractive index determines the angle of specular refraction, by Snell s Law. This effect is called dispersion because polychromatic light tends to be spread apart into monochromatic light, producing saturated ....

R. Victor Klassen. Modeling the effect of the atmosphere on light. ACM Transactions on Graphics, 6(3):215--237, 1987.

....are proposed. Finally, in section 6, the proposed method is applied to the display of natural scenes and buildings to demonstrate the usefulness of the method. 2 Previous Work Klassen tried to display sky color by taking into account spectral distribution due to particles in the atmosphere [Klassen 87] The method, however, has the following problems: the atmosphere is approximated as multiple layers of plane parallel atmosphere with uniform density. Thus, the method is different from the actual physical phenomenon. An improved method of calculating sky color, which approximates the actual ....

R. V. Klassen, Modeling the Effect of the Atmosphere on Light , ACM Trans. on Graphics, Vol. 6, No. 3 (1987), pp. 215-237.

....atmosphere has an intrinsic emission of visible light due to photochemical luminescence from atoms and molecules in the ionosphere. It accounts for one sixth of the light in the moonless night sky. Several authors have examined similar issues of appearance and illumination for the daylight sky [8, 20, 32, 35, 43, 33]. To our knowledge, this is the first computer graphics paper that examines physically based simulation of the nighttime sky. We restrict ourselves to natural lighting, and we include all significant natural sources of illumination except for aurora effects (northern lights) Tone mapping To ....

R. Victor Klassen. Modeling the effect of the atmosphere on light. ACM Transactions on Graphics, 6(3):215--237, 1987.

....interval. The usefulness of the proposed method is demonstrated by several examples of clouds generated from satellite images of typhoons passing through Japan. 1. Introduction Recently, simulation of natural phenomena, such as water, smokes, fire, clouds, have been attempted in computer graphics[1][2] 3] 4] 5] 6] 7] Clouds play an important role when generating images of outdoor scenes, the earth viewed from outer space and the visualization of weather information. This paper proposes a method for modeling large scale clouds viewed from space such as typhoon. A lot of methods have been ....

R. V. Klassen, "Modeling the Effect of the Atmosphere on Light," ACM Trans. on Graphics, vol.6, No.4, pp. 215-237 (1987).

....to refer to such techniques. Investigators have studied atmospheric scattering with distinct goals. Physicists and navigators seek to predict how a particular atmosphere affects visual perception; computer graphics researchers simulate scattering rather than measure its effect in practice [4, 6]. Artists have used simulated atmospheric effects in paintings at least since the Renaissance [1] Our purpose is new: we use atmospheric scattering as a beneficial source of information about geometric relationships among objects and a viewer. Light power and intensity are modified principally ....

.... was developed by Lord Rayleigh in 1871, after a long period where researchers postulated that the sky was blue due to the presence of water in the atmosphere [7] If particles in the atmosphere are spherical or small, light is scattered symmetrically with respect to incident rays of light [4]. We represent the portion of light that is scattered by a function B( the angular scattering function. The variable is the angle between the incident ray of light and the emanating ray of light; is the wavelength. Assumption 1 The scattering function is symmetric with respect to the ....

R. V. Klassen. Modeling the effect of the atmosphere on light. ACM Transactions on Graphics, 6(3):215--237, July 1987.

....physical approximation for the formation and animation of clouds. Gardner, 8] has use solid textured hollow ellipsoids in modeling clouds and more recently produced animations of smoke rising from a forest fire [9] Other approaches include the use of height fields [14] constant density media [13, 15], and fractals [21] The author has developed several approaches for modeling and controlling the animation of 3 1 gases [2, 7, 5, 3, 1] Recently, Stam has used fuzzy blobbies as a three dimensional model for animating gases with good results [20] The purpose of these notes is to describe my ....

.... addition needed to the spherical attractor procedure: Move the Volume of the Steam the shifting is based on the height above the cup (parms[13] parms[14] and the frame range for increasing the strength of the attractor. This is gotten from ratio mult that is calculated above. 3 18 Have the maximum strength increase from frame parms[4] to ....

Klassen, R. Victor. Modeling the Effect of the Atmosphere on Light. ACM Transaction on Graphics 6, 3 (July 1987), 215--237.

....the radiance of any point in the sky hemisphere may be determined. 4.2.3 Spectral Distribution The scattering processes described in Section 4.2 show that the specular distribution of sky light is dependent upon the extent and type of scattering that incident solar radiation undergoes. Klassen [65] and Inakage [55] have shown that, by modelling the various scattering processes, the spectral Chapter 4. Natural Illumination 54 attenuation of light due to the atmosphere can be modelled. A similar approach has been used by Tadamura et al. 125] which they show to match closely the CIE ....

R. V. Klassen. Modeling the effect of the atmosphere on light. ACM Transactions on Graphics, 6(3):215--237, July 1987.

....physical approximation for the formation and animation of clouds. Gardner, 6] has use solid textured hollow ellipsoids in modeling clouds and more recently produced animations of smoke rising from a forest fire [7] Other approaches include the use of height fields [12] constant density media [11, 13], and fractals [19] The author has developed several approaches for modeling and controlling the animation of gases [2, 5, 4, 3, 1] Recently, Stam has used fuzzy blobbies as a three dimensional model for animating gases with good results [18] The purpose of these notes is to describe the ....

Klassen, R. Victor. Modeling the Effect of the Atmosphere on Light. ACM Transaction on Graphics 6, 3 (July 1987), 215--237.

....account and assume random polarization everywhere. This should cause some unease, because in simple instances polarization can play an important role even when the emitted light is randomly polarized [40, 23] To add to the unease, note that the light coming from the sky is partially polarized [19]. For engineering applications where accuracy is critical, polarization should be accounted for. For the rest of this paper we will assume that a world without polarized light would not look much different, so ignoring polarization will be acceptable for appearance based applications. This is ....

R. V. Klassen. Modeling the effect of the atmosphere on light. ACM Transactions on Graphics, 6(3):215--237, July 1987.

....sunset images. 1.1 Previous 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 ....

Klassen R V, Modeling the effect of the atmosphere on light, ACM Trans. Graph. 6(3), July 1987, 215-237.

....relevant literature. 2.1 Previous Work in Natural Lighting Much work has been done on modeling daylight with different atmospheric effects and designing global illumination models including such light sources. Several models with different complexity were proposed to compute skylight intensities [1, 13, 8, 7, 3]. The public domain system Radiance [20] provides source code ( gensky and skybright ) to compute sky luminance using the CIE standard sky distribution model [1] for a given setup of hour, day, month, position on earth, and several weather specific parameters. The sun position can also be ....

R. Victor Klassen. Modeling the effect of the atmosphere on light. ACM Transactions on Graphics, 6(3):215--237, July 1987.

....the transmittance. The simplifications we made allows for an algorithm that can be used in real time applications. The final obscurant cloud is not of as high quality as Gardner s model, but it provides for real time obscurant usable on hardware currently available. C. TIME OF DAY Klassen [KLAS87] presents a method of determining sky color by approximating the atmosphere as multiple layers of parallel planes each containing a partial atmosphere of uniform density. His method calculates the reduction in light intensity caused by Rayleigh particle scattering. He then determines the color of ....

....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 accurate method known to date that is able to produce a background sky quickly. Hence it is up to user to develop an algorithm best suited for the task at hand. D. PREVIOUS RESEARCH SUMMARY The methods presented here by Gardner and Nishita, although providing high quality images of ....

Klassen, V. R., "Modeling the Effects of the Atmosphere on Light," acm Transaction on Graphics, Vol. 6, No 3, July 1987, pp. 215-237.

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Klassen,R.V., "Modeling the Effect of the Atmosphere on Light" , ACM Transactions on Graphics, 6(3), pp.215-237 (1987).

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R.V. Klassen, "Modeling the Effect of the Atmosphere on Light," ACM Transaction on Graphics, Vol. 6, No. 3,(1987),pp. 215-237.

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KLASSEN V. R.: Modeling the effect of the atmosphere on light. ACM Transactions on Graphics 6, 3 (July 1987), 215--237. 2

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KLASSEN, R. Modeling the effect of the atmosphere on light. ACM Trans. on Graphics 6, 3 (1987), 215--237.

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Klassen, R. Victor. Modeling the Effect of the Atmosphere on Light. ACM Transaction on Graphics 6, 3 (July 1987), 215--237.

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R.V.Klassen, "Modeling the Effect of the Atmosphere on Light," ACM Transaction on Graphics, Vol.6, No.3 (1987) pp.215-237.

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R. Klassen, "Modeling the Effect of the Atmosphere on Light," ACM Transactions on Graphics, Vol. 6, No. 3, pp. 215-237, July 1987.

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