J. S. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient Rerendering of Naturally Illuminated Environments. In Fifth Eurographics Workshop on Rendering, pages 359--373, 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....the images generated by varying the parameters of the source can be represented as a function of a small number of sample images from the image space. For example, the image space of a 3D Lambertian surface is determined by a basis of three images, ignoring cast shadows [18] 19] 9] 4] [12], 17] In this case, the low dimensionality of the image space under lighting variations is useful for synthesizing novel images given a small number of model images or, in other words, provides the means for an image based rendering process in which sampled images replace geometric entities ....

....of the image space under varying lighting conditions was originally reported in [18] 19] in the case of Lambertian objects. Applications and related systems were reported in [9] 4] 8] Re rendering under more general assumptions, yet exploiting linearity of light transport, was reported in [12], 17] Work on class based synthesis and recognition of images (mostly with varying viewing positions) was reported in [5] 3] 7] 27] 26] 24] 25] 6] 2] 15] These methods adopt a reconstructionist approach (also see Section 3) in which a necessary condition for the process of ....

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J. Nimeroff, E. Simoncelli, and J. Dorsey, Efficient Re-rendering of Naturally Illuminated Environments, Proc. Fifth Ann. Eurographics Symp. Rendering, June 1994.

....[7] addressed the problem of replicating environmental illumination on a foreground subject when compositing into a background environment. This work illuminated the person from a large number of incident illumination directions, and then computed linear combinations of the resulting images as in [18] to show the person as they would appear in a captured illumination environment [17, 6] This synthetically illuminated image could then be composited over an image of the background, allowing the apparent light on the foreground object to be the same light as recorded in the real world ....

NIMEROFF, J. S., SIMONCELLI, E., AND DORSEY, J. Efficient rerendering of naturally illuminated environments. Fifth Eurographics Workshop on Rendering (June 1994), 359--373.

....frequency space rotational convolution formula in terms of spherical harmonics. Inui et al. 11] is a good reference for background on spherical harmonics and their relationship to rotations. Our use of spherical harmonics to represent the lighting is similar in some respects to previous methods [25] that use steerable linear basis functions. Spherical harmonics, as well as the closely related Zernike Polynomials, have been used before to represent BRDFs [3, 14, 33] Spherical harmonics are the analog on the sphere to the Fourier basis on the line or circle. The spherical harmonic Ylm is ....

J. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient re-rendering of naturally illuminated environments. In EGWR 94, pages 359--373.

....resemblance between light fields and BRDF, since they are both functions of 4 variables. In fact we have been using this fact to use similar wavelet projections to represent and compress them [lalo97] Closely related to our goal are recent efforts to re render scenes under natural illumination [nime94, roma95], and to extract an illumination model from several views of a real object [sato97] 2.5 State of the Art One can say that the field of Image Based rendering has matured a lot in a few short years (and was the subject of a workshop last year in Monterey, Ca) but that a lot of work remains to be ....

Jeffry S. Nimeroff, Eero Simoncelli, and Julie Dorsey. "Efficient Re-rendering of Naturally Illuminated Environments ". Fifth EurographicsWorkshopon Rendering, pp. 359--373, June 1994.

....characteristics, such as a spotlight. 2. Basic Idea Assuming multiple light sources, luminance at a certain point is obtained by calculating the luminance from each light source and summing them. This means linearity is maintained in the calculation of luminance [Kajiya 86, Schoenenman 93, Nimeroff 94] In general, luminance calculation obeys the two following properties [Nimeroff 94] 1. Luminance from two light sources is equivalent to the sum of luminances from the individual light sources. 2. Multiplying the luminance from a light source by a factor w is equivalent to multiplying the ....

....sources, luminance at a certain point is obtained by calculating the luminance from each light source and summing them. This means linearity is maintained in the calculation of luminance [Kajiya 86, Schoenenman 93, Nimeroff 94] In general, luminance calculation obeys the two following properties [Nimeroff 94] 1. Luminance from two light sources is equivalent to the sum of luminances from the individual light sources. 2. Multiplying the luminance from a light source by a factor w is equivalent to multiplying the intensity of the light source by w. Nimeroff et al. applied this linearity of ....

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Nimeroff, J. S., Simoncelli, E. and Dorsey, J. Efficient Re-rendering of Naturally Illuminated Environments. Proceedings of 5th Eurographics Workshop on Rendering, pp. 359-373 (1994).

....the following two conditions must be satisfied: The intensity distribution of the sky should be expressed with the smallest possible number of basis functions. Any of the intensity distributions of the sky should be expressed with a linear combination of basis functions. Nimeroff et al. Nimeroff 94] proposed an efficient method of calculating the illuminance on surfaces due to light from the sky when the position of the sun is altered. In the method, the terms depending on the sun position are extracted from the distribution of the skylight and expanded into a series of basis functions. ....

J. S. Nimeroff, E. Simoncelli and J. Dorsey, Efficient Re-rendering of Naturally Illuminated Environments, Proceedings of 5th Eurographics Workshop on Rendering (1994), pp. 359-373.

....computer graphics, although it may be new to photography. One application is lighting design [10, 7] in which a configuration of lights is computed from a specification of desired illumination. Other uses of the linearity of rendering include representing the phases of sunlight using basis images [8] and work involving lighting design for opera [3] and real time building walkthroughs [1] 2. Inverse Lighting The problem of inverse lighting can be stated as follows: given a photograph of an object, a 3D model of that object (including its reflectance) and a description of the camera, ....

J. S. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient re-rendering of naturally illuminated environments. In Fifth Eurographics Workshop on Rendering, pages 359-- 373, Darmstadt, Germany, June 1994.

....the bidirectional reflection distribution function (BRDF) of different materials by, e.g. Cabral [3] and Westin et al. 29] Koenderink and van Doorn [17] proposed replacing the spherical harmonics basis with the Zernike polynomials, since BRDFs are defined over a half sphere. Nimeroff et al. [23]. Dobashi et al. 5] and Teo et al. 26] explore specific lighting configurations that can be represented efficiently as a linear combination of basis lightings (e.g. daylight) Dobashi et al. 5] in particular use spherical harmonics to form such a basis. D Zmura [6] was first to point out that ....

J. Nimeroff, E. Simoncelli, J. Dorsey, "Efficient re-rendering of naturally illuminated environments, " 5th Eurographics Workshop on Rendering, 1994.

....of estimated texture parameters for the novel image. 8.6 Extendibility The framework described here can easily be extended to handle parameters other than just shape and texture. Illumination modeling can be included in the current system by creating a separate basis for illumination variation[30]. If the prototype images are taken appropriately under different illumination conditions (say, with frontal light source) the illumination can be modeled separately. Illumination prototypes can be obtained by taking several images of the average reference image under various lighting condition. ....

J. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient re-rendering of naturally illuminated environments. In Proceedings of the Fifth Annual Eurographics Symposium on Rendering, Darmstadt, Germany, June 1994.

....of energy to the final image this is a reasonable approach. Even in this case the number of vectors is the product of the number of (different) light sources and the number of (different) surfaces in the scene. But one property helps us here, namely that rendering obeys the rule of superposition [31], which means that we can render an image independently for each light source and then simply add the generated images together. The result that we get is identical to rendering the scene with all light source turned on at once. 6.2. Viewer for Spectral Images 82 In the case of finding an optimal ....

Jeffry S. Nimeroff, Eero Simoncelli, and Julie Dorsey. Efficient re-rendering of naturally illuminated environments. Proceedings of Fifth Eurographics Workshowp on Rendering, pages 359--373, June 1994.

....of estimated texture parameters for the novel image. 8.6 Extendibility The framework described here can easily be extended to handle parameters other than just shape and texture. Illumination modeling can be included in the current system by creating a separate basis for illumination variation[30]. If the prototype images are taken appropriately under different illumination conditions (say, with frontal light source) the illumination can be modeled separately. Illumination prototypes can be obtained by taking several images of the average reference image under various lighting condition. ....

J. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient re-rendering of naturally illuminated environments. In Proceedings of the Fifth Annual Eurographics Symposium on Rendering, Darmstadt, Germany, June 1994.

....can be moved at interactive rates. Dorsey et al. 10] render a scene under various lighting conditions and then synthesize a new image by taking a linear combination of the ren derings. In effect, they store at each pixel the contributions from a set of light sources. Similarly, Nimeroff et al. [19] compute linear combinations of images that have been pre rendered under daylight conditions. By suitably approximating the angular distribution of the daylight, they construct steerable basis functions that model daylight for arbitrary positions of the sun. This approach has been demonstrated on ....

Jeffry S. Nimeroff, Eero Simoncelli, and Julie Dorsey. Efficient re-rendering of naturally illuminated environments. In Fifth Eurographics Workshop on Rendering, pages 359--373, June 1994.

....be convex. Third, the illumination must be fixed. If we ignore interreflections, this limitation can be addressed by augmenting light fields to include surface normals and optical properties. To handle interreflections, we might try representing illumination as a superposition of basis functions [Nimeroff94]. This would correspond in our case to computing a sum of light fields each lit with a different illumination function. It is useful to compare this approach with depth based or correspondence based view interpolation. In these systems, a 3D model is created to improve quality of the ....

Nimeroff, J., Simoncelli, E., Dorsey, J., "Efficient Rerendering of Naturally Illuminated Scenes," Proc. Fifth Eurographics Rendering Workshop, 1994, pp. 359-373.

....reflectance properties in real environments. A survey of some of the methods is in Marschner [21] Certain work has shown that changing the lighting in a scene does not necessarily require knowledge of the surface reflectance properties taking linear combinations of a large set of basis images [24, 35] can yield images with novel lighting conditions. Recent work in laser range scanning and image based modeling has made it possible to recover accurate geometry of real world scenes. A number of robust techniques for merging multiple range images into complex models are now available [34, 30, 4, ....

NIMEROFF,J.,SIMONCELLI,E.,AND DORSEY, J. Efficient re-rendering of naturally illuminated environments. In 5th Eurographics Workshop on Rendering (1994).

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Jeffry Nimeroff, Eero Simoncelli, and Julie Dorsey. Efficient re-rendering of naturally illuminated environments. In 5th Annual EurographicsWorkshop on Rendering, pages 359-- 374, June 13--15 1994.

....to perform the search. The user provides the parameters to perform an initial rendering and then can work interactively assigning new parameters to the surface elements and then reapplying the optimization algorithm. Wehavebegun to solve an inverse problem based on our steerable daylight model [Nimeroff et al. 1994]. Given any image I , we can easily solve for the least squares best choice of weights # n for 28 approximating that image with a set of rendered basis images, I n . The solution is: # = B ,1 c; where c is the vector 0 B B B B B B B B B B I # I 1 I # I 2 . I # I N 1 C C C C C C C C ....

Nimeroff, J. S., Simoncelli, E., and Dorsey, J. (1994). Efficient rerendering of naturally illuminated environments. In 5th Annual Eurographics Workshop on Rendering, pages 359--374. 33

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J. S. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient Rerendering of Naturally Illuminated Environments. In Fifth Eurographics Workshop on Rendering, pages 359--373, 1994.

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Nimeroff,J.S., Simoncelli,E., and Dorsey,J., "Efficient Re-rendering of Naturally Illuminated Environments", Eurographics Workshop on Rendering, pp.373-388 (1994).

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NIMEROFF,J.,SIMONCELLI, E., AND DORSEY, J. Efficient re-rendering of naturally illuminated environments. In 5th Eurographics Workshop on Rendering (1994).

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NIMEROFF, J., SIMONCELLI, E., AND DORSEY, J. Efficient re-rendering of naturally illuminated environments. In 5th Eurographics Workshop on Rendering (1994).

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NIMEROFF,J.S.,SIMONCELLI, E., AND DORSEY, J. Efficient rerendering of naturally illuminated environments. Fifth Eurographics Workshop on Rendering (June 1994), 359--373.

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J. Nimeroff, E. Simoncelli, and J. Dorsey. Efficient rerendering of naturally illuminated environments. In Eurographics Symposium on Rendering, Darmstadt, Germnay, June 1994.

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NIMEROFF,J.S.,SIMONCELLI, E., AND DORSEY, J. Efficient rerendering of naturally illuminated environments. Fifth Eurographics Workshop on Rendering (June 1994), 359--373.

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J.S. Nimeroff, E. Simoncelli, and J. Dorsey, "Efficient Re-Rendering of Naturally Illuminated Environments," Proc. Fifth Eurographics Workshop Rendering, pp. 359-373, 1994.

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NIMEROFF, J. S., SIMONCELLI, E., AND DORSEY, J. Efficient rerendering of naturally illuminated environments. Fifth Eurographics Workshop on Rendering (June 1994), 359--373.

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