In computer graphics, a polyline is a continuous line that is composed of one or more connected straight line segments, which, together, make up a shape. You can create a polyline by specifying the endpoints of each segment. In draw programs, you can treat a polyline as a single object or divide it into its component segments.

Polylines are used in geographic information systems (GIS) and computer-aided design (CAD) software to represent boundaries, roads, rivers, and other lines on maps. In general, they are used to represent an object in two-dimensional or three-dimensional space, and they can be open, closed, or a combination of both.

What Is a Polyline?

Polylines, also sometimes known as multi-lines or contour lines, are lines that have been drawn in the shape of a polygon. Polylines are frequently used for display purposes in AutoCAD. But you cannot easily draw an actual polyline (which is defined by a series of connected line segments) in AutoCAD, as it only allows you to make arcs and circles that would not form a continuous line or curve. Within AutoCAD, polylines can be created by using the POLYLINE command in the command line.

Polyline Use Case: Digitized Maps

Polylines can be used to graphically represent an area, such as a river or road. They are often used to digitize vector data from scanned maps into GIS software programs like ArcGIS, which is made by Esri.

The process of converting these scanned maps into digital format involves tracing over the original map with the onscreen mouse cursor until all features have been traced onto the computer program’s interface. This allows users to create their own datasets using any kind of geographic information systems software they choose. With this method, users also do not have to purchase expensive proprietary mapping products from companies like Esri or Intergraph Corporation.

Read next: The Best CAD/CAM Software

Webopedia Staff
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