NOTICE: help.openstreetmap.org is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum

We're programming an app for Windows Phone 7, and we're using Open Street Map (OSM) as our data source.

We're using this URI: http://api.openstreetmap.org/api/0.6/map?bbox=32.0846,034.8415,32.3846,035 and we're filling in coordinates according to the current position of the app's user.

The data we receive is : "nodes", "way", and "relation".

This is our question:

  • Some of the Nodes have "tags" in them and some don't. What's the difference between the two kinds of nodes?

asked 27 Aug '13, 14:03

yehudit's gravatar image

yehudit
61667
accept rate: 0%

edited 27 Aug '13, 20:59

MagicFab's gravatar image

MagicFab
935101622

4

Not directly related to the question, but related to the fact that you're hitting the API directly - have you had a read of the API terms of use?

(27 Aug '13, 14:29) SomeoneElse ♦

As the others told you, only the nodes have geographical coordinates. Ways are simply lists of nodes and their graphical representation is a line consisting of segments connecting consecutive nodes.

Relations are groups of nodes or ways.

A simple example of different tagging is a residential street with pedestrian crossing. The street would bear a highway=residential tag, while most of the nodes would have no tag at all. Only the node located in the place of the crossing would have a highway=crossing tag.

Be aware that many features might be represented by different elements. For example a shop (e.g. shop=convenience) might be a single node or a polygon (a closed way) outlining the building.

A simple road might be a way, but expect most of the highways to be a relation, grouping segments and junctions together.

permanent link

answered 27 Aug '13, 14:45

emes's gravatar image

emes
251459
accept rate: 0%

nodes carry the geographic coordinates in the OSM data model. A way only gets geometry via the nodes that are members of it. Most of the time such nodes will be untagged and only serve to determine the way geometry.

See for example http://en.flossmanuals.net/openstreetmap/the-osm-data-model/

permanent link

answered 27 Aug '13, 14:09

SimonPoole's gravatar image

SimonPoole ♦
44.7k13326701
accept rate: 18%

1

Also have a look at the relevant page of the beginners' guide - that explains the sorts of data contained within OSM.

(27 Aug '13, 14:24) SomeoneElse ♦

Any node can have tags. Nodes without tags are usually points that help define the geometry of a way (as the latitude and longitude are properties of the node). Some nodes in ways may have tags (such as highway=crossing) but many won't. Nodes that have no tags and aren't part of a way can just be ignored generally.

This page might help.

permanent link

answered 27 Aug '13, 14:11

EdLoach's gravatar image

EdLoach ♦
19.5k16156280
accept rate: 22%

1

Nodes which have no tags and aren't part of a way could still be a member of a relation :).

(27 Aug '13, 14:16) scai ♦
Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here

By RSS:

Answers

Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:

×113
×6
×6

question asked: 27 Aug '13, 14:03

question was seen: 5,772 times

last updated: 27 Aug '13, 20:59

NOTICE: help.openstreetmap.org is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum