Working with Spatial Data
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Map Features
Map features are the geographic features that appear on a map. In Autodesk
MapGuide, map features are points, such as fire hydrants and cities,
polylines, such as rivers and roads, and polygons, such as lakes and land
parcels. Each map feature has a name, an optional URL link, and geometric
data specified by one or more coordinate pairs.
The files containing the spatial data can also contain compound map
features, such as polypolylines and polypolygons. Polypolylines are multiple
polylines grouped as one to represent compound line features, such as road
networks and river systems. Polypolygons represent compound area features,
such as islands in a lake.
The following sections describe each of the types of map features you might
have in your Spatial Data Files.
Points
A point is single place on a map, such as a telephone pole, or a city. Every
point corresponds to a single coordinate pair that locates the point’s symbol
or text on the map. To use the points from a Spatial Data File in a map, you
create a point layer.
Lines/Polylines/Polypolylines
A line represents a linear feature, such as a street, river, or sewer pipe. A
polyline is simply a line with multiple segments, such as a winding road. A
polypolyline is a single feature that includes two or more polylines; this is a
convenient way to group related polylines into one map feature so that they
can be selected or linked to a database as a single entity. The starting point
and the ending point of each line segment in a line, polyline, or polypolyline
has a coordinate pair, so that a polyline with several line segments, for
example, will have several coordinate pairs that define the polyline.
Autodesk MapGuide treats lines, polylines, and polypolylines the same
way—to use the lines, polylines, and polypolylines from a Spatial Data File
in a map, you create a polyline layer.
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