Realistic Illumination Research Articles

Analytical SAR computation in a multilayer elliptic cylinder: The near‐field line‐current radiation case

In this paper, a previously proposed analytical procedure for the computation of the specific absorption rate (SAR) inside a biological elliptic cylinder model is extended to the case in which the body is illuminated under near-field conditions. The elliptic model is made up of layers of different biological tissues and the source is constituted by a line-current distribution. The recursive procedure in which the field is expressed in terms of Mathieu function is modified to express the incident electromagnetic wave produced by the line current. The new procedure makes it possible to check and validate numerical solutions obtained by accurate numerical techniques for SAR prediction, under more realistic illumination condition. Bioelectromagnetics 21:473–479, 2000. © 2000 Wiley-Liss, Inc.

Analytical SAR computation in a multilayer elliptic cylinder: The near-field line-current radiation case

In this paper, a previously proposed analytical procedure for the computation of the specific absorption rate (SAR) inside a biological elliptic cylinder model is extended to the case in which the body is illuminated under near-field conditions. The elliptic model is made up of layers of different biological tissues and the source is constituted by a line-current distribution. The recursive procedure in which the field is expressed in terms of Mathieu function is modified to express the incident electromagnetic wave produced by the line current. The new procedure makes it possible to check and validate numerical solutions obtained by accurate numerical techniques for SAR prediction, under more realistic illumination condition.

The Collocation Method for Solving the Radiosity Equation for Unoccluded Surfaces

The radiosity equation occurs in computer graphics, and its solution leads to more realistic illumination for the display of surfaces. We consider the behavior of the radiosity integral operator, for smooth and piecewise smooth surfaces. A collocation method for solving the radiosity equation is proposed and analyzed. The method uses piecewise linear interpolation; and for one particular choice of such linear interpolation, it is shown that superconvergence results are obtained when solving on a smooth surface. Numerical results conclude the paper.

Dynamic radiosity shadows for interactive virtual environments

Current state-of-the-art virtual reality (VR) systems provide realistic illumination only for static scenes, since shadows are calculated off-line and cannot be updated at interactive rates. This paper presents a new method for incorporating realistic radiosity shadows also in interactive VR applications. A radiosity process and the VR rendering process are coupled. User interactions trigger the radiosity process, which updates the illumination by providing corrected vertex colors. To speed up radiosity updates, coherences are exploited. Thus, on-line updated radiosity shadows can be integrated into interactive, dynamic virtual environments, providing a high degree of visual realism.

Dynamic radiosity shadows for interactive virtual environments

Current state-of-the-art virtual reality (VR) systems provide realistic illumination only for static scenes, since shadows are calculated off-line and cannot be updated at interactive rates. This p...

The same origin ray set query for realistic illumination: Algorithm and analysis

AbstractThe same origin ray set (SORS) is a computational primitive which can be used by ray tracing, radiosity and multiple pass illumination simulation algorithms for realistic image synthesis. A SORS consists of a set of rays emanating from the same point in space. The SORS query computes the first object intersected by each ray and the intersection point. In this paper we present an efficient projection algorithm for computing a SORS query for polygonal scenes. The algorithm achieves its efficiency by separating ray‐polygon intersection detection from the computation of the intersection point between the ray and the polygon's plane. The algorithm can be integrated with all current illumination acceleration schemes. We analyse the projection algorithm and compare it to the alternative of computing the SORS query one ray at a time. The analysis' results are expressed in terms of a few intuitive parameters, measuring the success of the acceleration scheme in culling irrelevant objects and the concentration of the ray set. The projection algorithm can be up to five times more efficient, depending on these parameters and the quality of the image. The relative advantage of the projection increases with image quality.

Review Of Colour Terms And Simultaneous Contrast Research For Cartography

Colours that are next to a map colour change its appearance by simultaneous contrast (the term induction is also used to describe the effect). The problem of simultaneous contrast on maps has been described repeatedly in the general literature on colour use in cartography and has been recognized as a confounding variable in cartographic research on colour. This review article clarifies important distinctions between lightness constancy and brightness contrast effects that interfere with the interpretation of the results of previous research. Likewise, induced changes in hue are often described as shifts toward the complement of the surrounding colour but many different definitions of complementarity exist, and these distinctions are described. Review of the induction literature from other disciplines reveals conflicting conclusions based on varied stimulus configurations that do not approximate the complexity of a map. To establish a perceptual structure relevant to the map reading context, induction must be judged under realistic illumination conditions and test colours must be embedded in a matrix of other colours that includes reference whites. Review of past attempts to explain induced changes in colour reveals that the opponent process approach is the most common and promising avenue for modelling induction.

A lighting evaluation of a facility for the elderly.

A residential facility for the aged was evaluated for their illumination needs. Only the shared facility and grounds immediately surrounding it were considered. The facility evaluated is one of the most modern and the lighting design is considered its best feature. The age of residents occupying the facility ranges from 60 to 85 years. The lighting evaluation included administering a lighting adequacy/inadequacy questionnaire and measurement of actual light levels in the various parts of the facility during the day and after dark hours. The results indicated that lighting in approximately half the areas surveyed was substandard. An attempt to develop recommendations for the lighting needs of the elderly was unsuccessful. It was concluded that realistic illumination level recommendations need to be developed for the elderly.