P. Moon and D.E. Spencer, The Photic Field, MIT Press, Cambridge, 1981.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....that they provide exactly the information necessary to optimize the task performance. The space of light rays is the most complete visual representation of a scene. It was first studied in the context of photometry and integral photography at the beginning of the 20th century (for an overview see [7]) A mathematical description of the space of light rays is given by the plenoptic function as described by [8] For each position in space it records the intensity of a light ray for every direction, time, wave length, and polarization, thus providing a complete description of all light rays. ....

P. Moon and D.E. Spencer, The Photic Field, MIT Press, Cambridge, 1981.

....moving imaging sensor to analyze how this structure is related to the rigid motion of the sensor. The idea of studying the space of light rays was already mentioned by Leonardo da Vinci [20] and further studied in the context of photometry at the beginning of the 20th century (for an overview see [14]) In computer graphics and computer vision recent work uses non perspective subsets of the plenoptic function to represent visual information to be used for image based rendering. Some examples are light fields [13] and lumigraphs [9] multiple centers of projection images [19] which have been ....

P. Moon and D.E. Spencer. The Photic Field. MIT Press, Cambridge, 1981.

....by luminaires [Levin71, Ashdown93] For the remainder of this paper we will be only concerned with 4D light fields. 1 For those familiar with Gershun s paper, he actually uses the term light field to mean the irradiance vector as a function of position. For this reason P. Moon in a later book [Moon81] uses the term photic field to denote what we call the light field. Although restricting the validity of the representation to free space may seem like a limitation, there are two common situations where this assumption is useful. First, most geometric models are bounded. In this case free space ....

Moon, P., Spencer, D.E., The Photic Field, MIT Press, 1981.

....terms of the previously defined parameters, the incident light energy field function specifies the light energy arriving at the point (x,y,z) from direction of wavelength l and Stokes parameter s at time t. This function is similar to the plenoptic function defined in [1] or the helios function [39]. The presentation considers only single pictures taken at time t, making time a constant and removing it from the parameterization of illumination functions. As a result, we only need to consider the subspace of the incident light energy field . For a point in free space, rays arriving at that ....

P. H. Moon and D. E. Spencer, The Photic Field, MIT Press, Cambridge, 1981.

.... One of the reasons Gershun (1936) and other early photometric theorists reformulated the fundamental photometric concepts in terms of field theory was to develop photometric theory as a special case of electromagnetic theory, where the wavelength of the electromagnetic radiation is zero (see Moon and Spencer 1981, Chap. 1) It is important to recognize that this reformulation introduces no new definitions or results; it is simply a more rational interpretation of the fundamental photometric concepts of luminous flux, luminance and illuminance. On the other hand, it does demonstrate that there is no need ....

Moon, P. and D. E. Spencer. 1981. The Photic Field. Cambridge, MA: MIT Press.

.... (they can describe surfaces that emit,reflect and absorb light) Alternatively, the radiometric field theory describes light by means of a three dimensional or five dimensional photic field that gives the value of a quantity describing light in any point of the space and for any orientation [Moon and Spencer, 1981]. The main importance of the photic field model resides in the fact that it describes light totally independent from any physical surfaces. The physical quantities describing light are now intrinsic properties of the photic field. Consequently the knowledge of the photic field in all points of the ....

Moon, P. and Spencer, D. E. (1981). The Photic Field. MIT Press, Cambridge, MA.

....in irradiance is to compute the differential form factor from a point on the film plane to a disk. This correctly accounts for the finite size of the disk, and the variation in angle as we integrate over the disk. This integral may be computed analytically[4] an elegant derivation may be found in [8]) F = 1 2 1 Gamma a 2 Z 2 Gamma r 2 p (a 2 Z 2 r 2 ) 2 Gamma 4r 2 a 2 (9) In real lens systems these analytical formulas overestimate the exposure. This is due to vignetting, the blocking of light by lens elements other than the aperture stop when a ray passes ....

Parry Moon and Domina Eberle Spencer. The Photic Field. The MIT Press, Cambridge, Massachusetts, 1981.

....because of cast shadows, without any change in surface normal. The second example is a spherical concavity excavated from a ground plane. A surprising result is that when shadowing, surface orientation, and interreflection effects are all modelled, surface radiance is constant within the concavity [11]. In particular, the interior of the concavity has the same local appearance under diffuse lighting as would a plane under point source at infinity lighting. It is clear from these examples that, under diffuse lighting, surface normal variations are neither necessary nor sufficient for radiance ....

P.H. Moon and D.E. Spencer. The Photic Field. MIT Press, Cambridge, Ma., 1981.

....on the ground and illuminated by a uniform diffuse source. A second example is a spherical concavity excavated from a ground plane. A surprising result is that when shadowing, surface orientation, and interreflection effects are all modelled, surface radiance is constant within the concavity [9]. In particular, a spherical concavity under diffuse lighting appears the same as a planar surface under point source at infinity lighting. The two examples illustrate that, under diffuse lighting, surface normal variations are neither necessary nor sufficient for radiance variations. Diffuse ....

P. Moon and D. Spencer. The Photic Field. MIT Press, Cambridge, Ma., 1981.

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