[OSM-dev] What exactly is a polygon?

[Rory McCann]

On 06/11/08 08:04, Till Harbaum wrote:
> What's the purpose of the area tag? Does it make a way
> a polygon, even if the first and last node are not identical?
> Is it used to make highways/waterways or railways a polygon?

As Jochen Topf mentioned you have to look at the tags to figure out if
something is an area. The purpose of the area tag is to explicitly mark
certain ways as areas when they would normally be interpreted as linear
features.

For example, large open pedestrian areas are modelled as a closed way
around their border tagged 'highway=pedestrian', 'area=yes'. Without the
area tag, it would be interpreted as a circular pedestrian way with
nothing in the middle.

Rory

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