wiki:Nl:Help/Concepts/Object

Version 2 (modified by DiGro, 13 years ago) ( diff )

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Objecten - De basis bouwstenen van OSM-gegevens en kaarten

JOSM helpt u om gegevens met betrekking objecten uit de echte wereld in te voeren in de geo-database van OSM. Ondanks de overweldigende complexiteit van objecten in de echte wereld die u kunt mappen, Verschaft JOSM slechts drie soorten objecten als basis bouwstenen voor kaarten: nodes, wegen, en relaties.

U kunt tags toewijzen aan objecten. Het is de toegewezen verzameling tags die een node een restaurant anders weergeeft dan een node die een kerk weergeeft, of een weg die een weg in een woonwijk weergeeft anders dan een weg die een rivier weergeeft, of een relatie die een busroute anders weergeeft dan een relatie die een fietsroute weergeeft.

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Nodes, wegen en relaties

Nodes

source:trunk/images/data/node.png Een node is een individueel punt met een gedefinieerde positie.

Wegen

source:trunk/images/data/way.png Een weg is een reeks nodes. Ondanks de naam vertegenwoordigt een source:trunk/images/data/way.png weg niet alleen wegen in de echte wereld. Een source:trunk/images/data/way.png weg in OSM wordt ook gebruikt om een rivier weer te geven, de grenzen van een land, of zelfs een gebouw.

Closed Ways (Areas)

If a source:trunk/images/data/closedway.png way is closed, i.e. if the last source:trunk/images/data/node.png node is the same as the first source:trunk/images/data/node.png node, it is also called an source:trunk/images/data/closedway.png area.

Relations

source:trunk/images/data/relation.png A relation is an sequence of other objects, for instance a sequence of source:trunk/images/data/way.png ways (representing road segments) and source:trunk/images/data/node.png nodes (representing bus stops) which represent a bus route. Each object participating in a source:trunk/images/data/relation.png relation can be assigned a role, for instance stop for a bus stop in the bus route, or forward for a road segment which is part of the bus route from the start to the terminal station.

Tags

A tag is a name/value pair assigned to an object. Tags are used to describe an object in detail. If we write foo=bar we mean The tag with key foo is assigned the value bar. Here are some examples:

  • name=Main road assigned to a way. This tag indicates that the name of the way is Main road.
  • amenity=restaurant assigned to a node. This tag indicates that the node represents a restaurant in the real-world.
  • route=bus assigned to a relation. This tag indicates that the relation represents a bus route.

Tags can be combined. An object can carry as many tags as necessary. Here's a more complex example:

highway=living_street
name=Main road
name:de=Hauptstrasse
maxspeed=30
hgv=no
oneway=yes

Assigned to a source:trunk/images/data/way.png way, this set of tags indicate, that the source:trunk/images/data/way.png way represents a living street with name Main road (the German name be Hauptstrasse). Speed is limited to 30km/h and heavy goods vehicles (hgv) are not allowed. Furthermore, it's a one way street.

You are free to assign an object whatever tag you feel necessary. However, there is a list of so called Map Features, i.e. a canonical list of tags with a well-defined meaning which are often used by mappers. Whenever possible you are adviced to stick to these tags because map renderers, routing engines, and other pieces of software rely on them.

In the source:trunk/images/dialogs/propertiesdialog.png [Dialog/Properties Properties Dialog] you can assign tags to an object, remove tags from an object, or edit assigned tags.

Object ids

The OSM server assigns each object a unique number, the object ID or OSM ID. A new object doesn't have an ID (it's ID is 0) until it is uploaded the first time to the OSM server.

Under source:trunk/images/preference.png Preferences -> source:trunk/images/preferences/display.png Display Settings -> Look and Feel it is possible to en- or disable the display of objects ids in the toggle dialogs.

With File -> source:trunk/images/downloadprimitive.png Download object ... (Ctrl+Shift+O) it is possible to download objects by Ids.

View -> source:trunk/images/about.png Info about Element (Ctrl+I) opens the objects' pages of selected objects on the OSM website in your web browser.

Alternatively, you can browse the objects directly by entering following address in your web browser:

http://www.openstreetmap.org/browse/[node/way/relation]/[ID]

Object versions

Each object has a version. The version is incremented whenever the object is uploaded to the server and the OSM server not only stores the most recent version of an object, but it's complete history.

In the source:trunk/images/dialogs/history.png [Dialog/History History Dialog] you can load the history of an object and launch the [Dialog/History#Workingwiththehistorybrowser History Browser]. The History Browser will show you the versions of a particular object.

Alternatively, View -> source:trunk/images/about.png Object history opens a page on the OSM website in your web browser which displays the object history, too.


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