Hall,R.A., and Greenberg,D.P., "A Testbed for Realistic Image Synthesis", IEEE CG&A, 3(8), pp.10-20 (1983).  Home/Search   Document Not in Database   Summary   Related Articles   Check

....computer graphics all the color information is typically converted to RGB format at the very beginning of the rendering process and all further computations are performed in this trichromatic space. However, the employment of only three bands of wavelengths introduces significant color distortions [1, 11] and loss of information which results in weaker color discrimination and inaccurate color identification. Another side effect is metamerism. When we capture RGB data we end up projecting an infinitely dimensional color space to a three dimensional space. This is many to one projection results in ....

R.A. Hall and D.P. Greenberg. "A Testbed for Realistic Image Synthesis." IEEE Computer Graphics and Applications, Vol. 3, No. 8, 1983. pp. 10-19.

....For most cases, describing color in the tristimulus space is sufficient for communicating color information to a human observer. However, if the whole computation of light reflection and transfer is performed in tristimulus space (see section 2) significant color distortions are introduced [6, 7]. Furthermore, the use of tristimulus representations introduces metameric colors, i.e. colors with the same tristimulus values but with distinct spectral power distributions [20, 11] Thus, it is impossible in vision algorithms to differentiate spectrally distinct colors which give rise to the ....

R.A. Hall and D.P. Greenberg, "A testbed for realistic image synthesis," IEEE Computer Graphics and Applications, Vol. 3, No. 8, November 1983, pp. 10-19.

....dimensional color space (usually RGB or La b [15] A rst solution to use this model with usual three dimensional colors would be to derive a spectrum for each color of the image and then to apply the spectral model. Several methods have been proposed to derive a spectrum from an RGB color[13, 10, 24]. Such derived spectra being very smooth and regular, the method proposed by Meyer[19] to make computations only for four representative wavelengths could possibly be used in order to reduce computational time of object composition. Another possibility is to use our model with the RGB color ....

R.A. Hall and D.P. Greenberg. A testbed for realistic image synthesis. IEEE CG&A, 3(6):10{ 20, 1983.

....with narrow bandwidth (eight 10nm wide filters as opposed to the typical three 75nm filters) The use of narrow filters increases the discriminatory power of our method. The advantage of the traditional RGB systems is that they resemble the human visual sensor. Unfortunately, as Hal land Greenberg[10] have shown, the employment of only 3 bands of wavelengths introduces significant colour distortions. An additional advantage of our technique over the more traditional band ratios is that spectral derivatives are used on a per pixel basis. They do not depend on neighbouring regions, an assumption ....

....600=red, 630=scarlet red, 660=mauve. The use of narrow bandpass filters allowed us to closely sample almost the entire visible spectrum. The dense narrow sampling permitted us to avoid sampling (or ignore samples) where the incident light may be discontinuous (see section 3. Hall and Greenberg[10] have demonstrated that such a sampling density provides for the reproduction of a good approximation of the continuous reflectance spectrum. The images were captured with a Sony XC 77 camera using a 25mm lens (fig. 2. The only source of illumination was a single tungsten light bulb mounted in a ....

Hall, R. A. and Greenberg, D. P., "A Testbed for Realistic Image Synthesis," IEEE Computer Graphics and Applications, Vol. 3, No. 8, 1983, pp. 10-19.

....Line Surface Algorithms; General Terms: Algorithms Additional Keywords and Phrases: Ray Tracing, Anti Aliasing Introduction Ray tracing is a very powerful yet simple approach to image synthesis. Though expensive computationally, it has generated some of the most realistic scenes to date [10, 13, 17]. It is also used for entertainment and computer aided design [9, 15] However, apart from the computationally expensive method of supersampling, no general method exists to remove artifacts created by aliasing. Furthermore, at present, there is no general procedure to decide what level of detail ....

Hall, R.A., and Greenberg, D.P., "A Testbed for Realistic Image Synthesis", IEEE Computer Graphics and Applications, Vol. 3(8), November 1983, pp. 10-20.

....There is a substantial body of work in this area which relies on conventional tri color RGB sensor data [7] and on chroma model based approaches [18] RGB data is prevalent, easy to collect and mimics human color sensitivity. Unfortunately, the RGB model produces significant colordistortions [8]. It is therefore a natural and practical approach to take in investigating skin recognition. What happens, however, if the constraint of using data from an RGB sensor is lifted Establishing ground truth measurements of skin reflectance provides the foundation for reasoning about new ....

Hall, R. A. and Greenberg, D. P. "A testbed for realistic image synthesis." IEEE Computer Graphics and Applications, Vol. 3, No. 8, 1983. pp. 10-19.

....a ray through a volume from front to back, we accumulate opacity. For instance, if we have an accumulated fi = 6, only 40 of the light we find will make it back to the eye. This means that any mistakes we make will be similarly scaled. Hall implemented a weight cutoff mechanism for a ray tracer [7] and Levoy adapted this technique to volume ray tracing: any rays which accumulated an ff larger than some threshold were terminated. Unfortunately this leads to a systematic bias in the image [1] We will develop or adapt two techniques to take advantage of accumulated opacity without introducing ....

Hall, R., and D. Greenberg "A testbed for realistic image synthesis," IEEE Computer Graphics and Applications, Vol. 3, No. 10, November 1983, pp. 10-20.

....in the modeling of light sources illuminating these environments. However, this is not the case. Most rendering systems rely on isotropic point sources with light direction controls (Warn 1983) or line and area (i.e. extended) sources modeled by discrete spatial arrays of point sources (Hall and Greenberg 1983, Brotman and Badler 1984, Verbeck 1984, Verbeck and Greenberg 1984, Houle 1991, and Houle and Fiume 1993) At best, a few systems model extended area sources as homogeneous one and twodimensional continua (Nishita et al. 1985, Tanaka and Takahashi 1991, Poulin and Amanatides 1990, Picott 1992, ....

Hall, R. and D. P. Greenberg. 1983. "A Testbed for Realistic Image Synthesis," IEEE Computer Graphics and Applications 3(11):10-20.

....[Amburn86] Green88] Upstill90] These are procedures for higher level objects that generate lower level primitives. They can provide some advantages for high level culling and changes in the level of detail of the model. A number of ray tracers allow new primitives to be added [Rubin80] [Hall83] [Wyvill85] Kuchkuda88] Kolb92] In all of these, adding a new primitive consists of adding a new ray intersection function to the ray tracer. None that we are aware of use a separate language to define the new primitives. There have also been a handful of scan line and Zbuffer systems that have ....

R. A. Hall and D. P. Greenberg, "A Testbed for Realistic Image Synthesis", IEEE Computer Graphics And Applications, volume 3, November 1983, pp. 10--20.

....appendix. Recursion of the beam tracer can be terminated by several criteria: 1) Maximum tree depth: 5 levels is common. y (2) Threshold of insignificance: determine if the intensit contributed by this branch of the tree will make a c perceptible difference (called adaptive tree depth ontrol in [Hall and Greenberg, 1983]) w (3) Polygon size: terminate when polygon area is belo some threshold, such as one pixel. s 2.2. Reflection and Refraction Transformation Reflection in a plane, which maps each point to its mirb ror image, is a linear transformation, and can be represented y a 4x4 homogeneous matrix. ....

Hall, Roy A., and Donald P. Greenberg, "A Testbed for A Realistic Image Synthesis." IEEE Computer Graphics and pplications, vol. 3, no. 8, Nov. 1983, pp. 10-20.

No context found.

Hall,R.A., and Greenberg,D.P., "A Testbed for Realistic Image Synthesis", IEEE CG&A, 3(8), pp.10-20 (1983).

No context found.

R. A. Hall and D. P. Greenberg, "A Testbed for Realistic Image Synthesis," IEEE Computer Graphics & Appl., 3(6), 1983, 10-20.

No context found.

Roy A. Hall and Donald P. Greenberg, "A Testbed for Realistic Image Synthesis," IEEE Computer Graphics & Appl., Vol. 3, No. 6, Nov. 1983, pp. 10-20.

No context found.

Hall, R.A. and Greenberg, D.P. "A Testbed for Realistic Image Synthesis." IEEE Computer Graphics and Application, Vol. 3, No. 8, 1983, pp. 10-19.

No context found.

R.Hall, D.Greenberg, A Testbed for Realistic Image Synthesis, Computer Graphics & Applications, v3, n8, p10-20, 1983

No context found.

Hall, R. A. and Greenberg, D. P. "A testbed for realistic image synthesis." IEEE Computer Graphics and Applications, Vol. 3, No. 8, pp. 10-19, 1983.

No context found.

Hall, Roy A., and Donald P. Greenberg. "A Testbed for Realistic Image Synthesis." IEEE CG&A, November 1983, p. 10-20. f65g

No context found.

. 10. R. Hall and D. P. Greenberg, "A testbed for realistic image synthesis," IEEE Computer Graphics & Appl. 3, 10-20

No context found.

Hall83 Roy A. Hall and Donald P. Greenberg, "A Testbed for Realistic Image Synthesis," IEEE Computer Graphics & Appl., Vol. 3, No. 6, Nov. 1983, pp. 10-20.

No context found.

R.Hall, D.Greenberg, A Testbed for Realistic Image Synthesis, Computer Graphics & Applications, v3, n8, p10-20, 1983

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC