Let P be a set of n points in the plane and O be a set of k lines passing through the origin. We show: (1) How to compute the O-hull of P in Θ(n log n) time and O(n) space, (2) how to compute and maintain the rotated hull OHθ(P ) for θ ∈ [0, 2π) in O(kn log n) time and O(kn) space, and (3) how to compute in Θ(n log n) time and O(n) space a value of θ for which the rectilinear convex hull, RHθ(P...

The aim of this paper is to study the concept of -induced L-fuzzy topological spaces. Some properties of the functions (namely Scott-continuous function) are studied. The Scott-continuous functions turn out to be the natural tool for studying the -induced L-fuzzy topological space. We also discuss the connections between some separations, countability and covering properties of an ordinary topo...

We study the Oβ-hull of a planar point set, a generalization of the Orthogonal Convex Hull where the coordinate axes form an angle β. Given a set P of n points in the plane, we show how to maintain the Oβ-hull of P while β runs from 0 to π in Θ(n log n) time and O(n) space. With the same complexity, we also find the values of β that maximize the area and the perimeter of the Oβ-hull and, furthe...

The visual hull is a geometric tool which relates the 3D shape of a concave object to its silhouettes or shadows. This paper develops the theory of the visual hull of objects bounded by smooth curved surfaces. From the basic definitions of visual hull we determine the surfaces which bound the visual hull of such objects. We show that these surfaces are patches of some surfaces which partition t...

We present simple output-sensitive algorithms that construct the convex hull of a set of n points in two or three dimensions in worst-case optimal O (n log h) time and O(n) space, where h denotes the number of vertices of the convex hull.

In a normed linear space X, consider a nonempty closed set K which has the property that for some r > 0 there exists a set of points xo € X\K, d(xoK) > r, which have closest points p(xo) € K and where the set of points xo — r((xo — p(xo))/\\xo — p(zo)||) is dense in X\K. If the norm has sufficiently strong differentiability properties, then the distance function d generated by K has similar dif...

We present a numerically stable and time and space complexity optimal algorithm for constructing a convex hull for a set of points on a plane. In contrast to already existing numerically stable algorithms which return only an approximate hull, our algorithm constructs a polygon that is truly convex. The algorithm is simple and easy to implement.