In this paper, we give a characterization of the visibility graphs of pseudo-polygons. We first identify some key combinatorial properties of pseudo-polygons, and we then give a set of five necessary conditions based off our identified properties. We then prove that these necessary conditions are also sufficient via a reduction to a characterization of vertex-edge visibility graphs given by O’R...

The problem of aggregation is considerable importance in many disciplines. In this paper, a new type of operator called visibility graph averaging (VGA) aggregation operator is proposed. This proposed operator is based on the visibility graph which can convert a time series into a graph. The weights are obtained according to the importance of the data in the visibility graph. Finally, the VGA o...

Let P be a simple polygon with n vertices. We present a new O(n)-time algorithm to compute the visible part of one edge from another edge of P . The algorithm does not alter the input and only uses O(1) variables and is therefore a constant-workspace algorithm. The algorithm can be used to make a constant-workspace algorithm for computing the weak visibility polygon from an edge in O(mn) time, ...

The visibility graph V(X) of a discrete point set X ⊂ R has vertex set X and an edge xy for every two points x, y ∈ X whenever there is no other point in X on the line segment between x and y. We show that for every graphG, there is a point setX ∈ R, such that the subgraph of V(X∪Z) induced by X is isomorphic to G. As a consequence, we show that there are visibility graphs of arbitrary high chr...

We present a lighting method for outdoor scenes with vegetation. The method is compatible with multiresolution trees generated using random L-systems. We include a sky dome model that gets the luminance and chromaticity values at several sampling points for different time and location. The samples are used to compute the light arriving to the objects in the scene depending on the insolation con...

In the paper, we consider the problem of computing visibility information on digital terrain models. Visibility problems on polyhedral terrains are classi ed according to the kind of visibility information computed into point visibility, line visibility and region visibility. A survey of the state-of-the-art of the algorithms for computing visibility is presented, according to the classi cation...

Visibility computation is crucial for computer graphics from its very beginning. The first visibility algorithms in computer graphics aimed to determine visible surfaces in a synthesized image of a 3D scene. Nowadays there are many different visibility algorithms for various visibility problems. We propose a new taxonomy of visibility problems that is based on a classification according to the ...

We present a visibility method that takes advantage of the graphics hardware to give fast answers to visibility queries. Our visibility method is designed to solve two types of visibility queries: point-based visibility queries, where several visibility queries share the same origin, and planebased visibility queries, where several visibility queries have their origins on the same plane. Both o...

In this paper we introduce a new class of partially ordered sets, called tree-visibility orders, extending the class of interval orders in a fashion similar to the extension of interval graphs to chordal graphs. This class contains interval orders, duals of generalized interval orders and height one orders. We give a characterization of tree-visibility orders by an innnite family of minimal for...