- Visibility (geometry)
**Visibility**is a mathematical abstraction of the real-life notion ofvisibility .Given a set of obstacles in the

Euclidean space , two points in the space are said to be**visible to each other**, if the line segment that joins them does not intersect any obstacles.Computation of visibility is among the basic problems in

computational geometry and finds applications incomputer graphics ,motion planning , and other areas.**Notions and problems***

Point visibility

*Edge visibility

*Visibility polygon

*Weak visibility

*Art gallery problem (The museum problem )

*Visibility graph

**Visibility graph of vertical line segments

*Watchman route problem

*Computer graphics applications:

**Hidden surface determination

**Hidden line removal

**z-buffering

**portal engine

*Star-shaped polygon

**Kernel of a polygon

*Isovist

*Viewshed

*Zone of Visual Influence **External links****oftware*** [

*http://www.VisiLibity.org VisiLibity: A free open source C++ library of floating-point visibility algorithms and supporting data types. A Matlab interface is also included.*]**References***cite book

name=AGTA

first=Joseph

last=O'Rourke

authorlink = Joseph O'Rourke (professor)

year=1987

title=Art Gallery Theorems and Algorithms

publisher= Oxford University Press

id=ISBN 0-19-503965-3

*cite book

first=Subir Kumar

last=Ghosh

year=2007

title=Visibility Algorithms in the Plane

publisher=Cambridge University Press

id=ISBN 0521875749

*cite book

author =Mark de Berg ,Marc van Kreveld ,Mark Overmars , andOtfried Schwarzkopf | year = 2000 | title = Computational Geometry | publisher =Springer-Verlag | edition = 2nd revised edition | id = ISBN 3-540-65620-0, 1st edition (1987): ISBN 3-540-61270-X Chapter 15: "Visibility graphs"

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