We define a natural class of graphs by generalizing prior notions of visibility, allowing the representing regions and sightlines to be arbitrary. We consider mainly the case of compact connected representing regions, proving two results giving necessary properties of visibility graphs, and giving some examples of classes of graphs that can be so represented. Finally, we give some applications ...

A new technique is presented for determining the positions where a range sensor should be located to acquire the surfaces of a complex scene. The algorithm consists of two stages. The first stage applies a voting scheme that considers occlusion edges. Most of the surfaces of the scene are recovered through views computed in that way. Then, the second stage fills up remaining holes through a sch...

purpose: the purpose of this study was to investigate the structure of the discipline categorization and its overlap with isi subject categories. this will help detect the systematic errors arising from the scientometrics studies. methodology: the scientometrics methodology was used. all articles which were indexed in the web of science database (2007) and also the articles citing them during 2...

We consider the problem of recognizing star-polygons under staircase visibility (s-visibility). We show that the s-visibility polygon from a point inside a simple orthogonal polygon of n sides can be computed in O(n) time. When the polygon contains holes the algorithm runs in O(n log n) time, which we prove to be optimal by linear time reduction from sorting. We present an algorithm for computi...

In this paper we study local routing strategies on geometric graphs. Such strategies use geometric properties of the graph like the coordinates of the current and target nodes to route. Specifically, we study routing strategies in the presence of constraints which are obstacles that edges of the graph are not allowed to cross. Let P be a set of n points in the plane and let S be a set of line s...

We introduce the notions of order type (or: dual arrangement) and visibility type (or: tangent visibility graph) for conngurations of disjoint convex sets in the plane. We develop optimal algorithms for computing and sweeping the order type, and also give a worst case optimal algorithm for computing the tangent visibility graph. The methods are based on a relation, introduced in this paper, bet...

introduction thermal infrared integrated dust index (tiidi) is one of indices that is presented in this direction. the index operates based on four brightness temperature difference including wavelengths 3.7, 8.6, 11 and 12 micrometer. according to the studies, btd (bt12-bt11) is used for cloud detection. btd (bt8.6-bt11) is the index for separation for dust from sandy surface and btd (bt3.7-bt...

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. ...

The pollution of particulate matter less than 2.5 microm (PM2.5) is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U.S. national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composi...