We review theoretical models to show that contrast reduction at a specific wavelength in the horizontal direction depends directly on the beam attenuation coefficient at that wavelength. If a black target is used, the inherent contrast is always negative unity, so that the visibility of a black target in the horizontal direction depends on a single parameter only. That is not the case for any o...

abstract in general, garmesh wind in rasht province increases the temperature by 9°c and reduces relative humidity by 47%. the direction of prevailing wind during the garmesh wind is southern and its average speed increases by 2 m/s to 5 m/s. the highest frequency of garmesh wind occurs at 09 and 12 utc in december and january. the occurrence of this phenomenon substantially increases the horiz...

This paper describes the application of a Doppler Light Detection And Ranging (LIDAR) system to the monitoring of visibility at the Hong Kong International Airport (HKIA). The backscattered power data from the LIDAR are inverted by Klett’s method (1981) into extinction coefficient and then into atmospheric visibility. A plan position indicator (PPI) scan of the LIDAR thus enables the production...

The paper considers representations of bipartite graphs as rectangle-visibility graphs, Le., graphs whose vertices are rectangles in the plane, with adjacency detenmned by horizontal and vertical visibility.1t is shown that, for p ~ q, Kp,q has a representation with no rectangles having collinear sides if and only if p ~ 2 or p = 3 and q ~ 4. More generally, it is shown that Kp;q is a rectangle...

Reconstruction of polygons from visibility information is known to be a difficult problem in general. In this paper, we consider a special case: reconstruction of orthogonal polygons from horizontal and vertical visibility information and show that this reconstruction can be performed in O(n logn) time.  2002 Elsevier Science B.V. All rights reserved.

We describe two current projects with our toolkit for siting multiple observers on terrain. (Both observers and targets are at some specified height above ground level. Observers can see targets, when not hidden by the terrain, out to a specified radius of interest.) Siting the observers so that they are intervisible, i.e., so that the visibility graph is a connected set, is the first project. ...

Bar k-visibility graphs are graphs admitting a representation in which the vertices correspond to horizontal line segments, called bars, and the edges correspond to vertical lines of sight which can traverse up to k bars. These graphs were introduced by Dean et al. [3] who conjectured that bar 1-visibility graphs have thickness at most 2. We construct a bar 1-visibility graph having thickness 3...

A shape visibility representation displays a graph so that each vertex is represented by an orthogonal polygon of a particular shape and for each edge there is a horizontal or vertical line of sight between the polygons assigned to its endvertices. Special shapes are rectangles, L, T, E and H-shapes, and caterpillars. A flat rectangle is a horizontal bar of height > 0. A graph is 1-planar if th...