## 11.4.2.3 Point Class 

A Point  is a geometry that represents a single location in coordinate space. 

## Point  Examples 

•Imagine a large-scale map of the world with many cities. A Point  object could represent each city. 

## 11.4.2.4 Curve Class 

•On a city map, a Point  object could represent a bus stop. 

## Point  Properties 

•X-coordinate value. 

•Y-coordinate value. 

• Point  is defined as a zero-dimensional geometry. 

•The boundary of a Point  is the empty set. 

A Curve  is a one-dimensional geometry, usually represented by a sequence of points. Particular subclasses of Curve  define the type of interpolation between points. Curve  is a noninstantiable class. 

## Curve  Properties 

•A Curve  has the coordinates of its points. 

•A Curve  is defined as a one-dimensional geometry. 

•A Curve  is simple if it does not pass through the same point twice, with the exception that a curve can still be simple if the start and end points are the same. 

## 11.4.2.5 LineString Class 

•A Curve  is closed if its start point is equal to its endpoint. 

•The boundary of a closed Curve  is empty. 

•The boundary of a nonclosed Curve  consists of its two endpoints. 

•A Curve  that is simple and closed is a LinearRing . 

A LineString  is a Curve  with linear interpolation between points. 

## LineString  Examples 

•On a world map, LineString  objects could represent rivers. 

•In a city map, LineString  objects could represent streets. 

## LineString  Properties 

•A LineString  has coordinates of segments, defined by each consecutive pair of points. 

•A LineString  is a Line  if it consists of exactly two points. 

•A LineString  is a LinearRing  if it is both closed and simple. 

