In this paper, we propose a method for maintaining the region visible from a moving point observer inside a planar scene. In this method, we check the observer position in discrete time-stamps to detect and apply changes to the visible or illuminated region of a moving point observer q, or VP(q). We efficiently maintain a list C(q) of edges in VP(q) which are subject to change during the motion...

In this paper we give tight lower bounds on the size of the visibility graph, the contracted visibility graph, and the bar-visibility graph of n disjoint line segments in the plane, according to their vertex-connectivity.

The 0− 1 matrix A contains a 0− 1 matrix M if some submatrix of A can be transformed into M by changing some ones to zeroes. If A does not contain M , then A avoids M . Let ex(n,M) be the maximum number of ones in an n×n 0−1 matrix that avoids M , and let exk(m,M) be the maximum number of columns in a 0− 1 matrix with m rows that avoids M and has at least k ones in every column. A method for bo...

This paper presents a visibility analysis tool for 3D urban environments and its possible applications for urban design practice. Literature exists for performing visibility analysis using various methods and techniques, however, tools that result from such research are generally not suitable for use by designers in practice. Our visibility analysis tool resides in Grasshopper, Rhino. It uses a...

A unit bar-visibility graph is a graph whose vertices can be represented in the plane by disjoint horizontal unit-length bars such that two vertices are adjacent if and only if there is a unobstructed, non-degenerate, vertical band of visibility between the corresponding bars. We generalize unit bar-visibility graphs to [1, k]bar-visibility graphs by allowing the lengths of the bars to be betwe...

The political utility of ethnicity is typically attributed to the ease with which it can be observed. However, ethnic visibility not universal, and I argue that its variation has implications; namely more visible group members support parties at higher rates because they have most gain (or lose) from ethnopolitical competition. Using original data Malawi, find individual-level indeed strongly a...