We consider variants of the art gallery problem where guard visibility is limited to a certain angular aperture α. We show that the problem is NP-hard even when guards can be located in the interior of the polygon. We then proceed to prove that both this problem and its vertex variant, where guard placement is restricted to the vertices of the polygon, are APX-hard. We observe that earlier cons...

Today, image gallery applications on mobile devices tend to be stand-alone and offline. For people who want to share photos with others, many add-on tools have been developed to connect the gallery applications to Internet services to enable photo-sharing. The authors argue that photocentric social interaction is best supported when the gallery application is fully integrated with an Internet s...

The Breast Surgery Gallery is a unique and innovative computer program of digital photographs depicting sequential images of oncoplastic and prophylactic breast surgery. Specialist breast nurse counselors developed the tool to provide education and assist in decision making for people facing oncoplastic and prophylactic breast surgery. This article presents a historical perspective of the devel...

Facial caricaturing process should be investigated and modeled from multiple viewpoints of three relations among the model, the caricaturist and the gallery. Furthermore, some kinds of interactive mechanism should be installed in order especially to implement the relation between the facial caricature generation system PICASSO[ I ] and gallery. In this paper, we propose a dynamic caricaturing s...

This paper focuses on a variation of the Art Gallery problem that considers open edge guards and open mobile guards. A mobile guard can be placed on edges and diagonals of a polygon, and the “open” prefix means that the endpoints of such edge or diagonal are not taken into account for visibility purposes. This paper studies the number of guards that are sufficient and sometimes necessary to gua...

Classicist. A casualty of the minimalist creed, Contreras quit making art in 1972 when he’d reduced his image to a dot. He began again in 1997. USC Fisher Gallery, Harris Hall. Hours: Tuesday through Saturday, noon to 5 p.m. Free. 213-740-4561

We explore the art gallery problem for the special case that the domain (gallery) P is an mpolyomino, a polyform whose cells are m unit squares. We study the combinatorics of guarding polyominoes in terms of the parameter m, in contrast with the traditional parameter n, the number of vertices of P . In particular, we show that ⌊ 3 ⌋ point guards are always sufficient and sometimes necessary to ...

Recent developments in photo-detectors and photo-detector systems are reviewed. The main emphasis is made on Silicon Photo-Multipliers (SiPM) novel and very attractive photo-detectors. Their main features are described. Properties of detectors manufactured by different producers are compared. Different applications are discussed including calorimeters, muon detection, tracking, Cherenkov light ...

We propose a unified framework to study the walk problem in a polygonal area by two collaborative guards. A walk is conducted by the two mobile guards on the area’s boundary. They start at an initial boundary point, move along the boundary, and may possibly meet together again at an ending boundary point. It is required that the two guards maintain their mutual visibility at all times. Dependin...

We address the problem of stationing guards in vertices of a simple polygon in such a way that the whole polygon is guarded and the number of guards is minimum. It is known that this is an NP-hard Art Gallery Problem with relevant practical applications. In this paper we present an approximation method that solves the problem by successive approximations, which we introduced in [21]. We report ...