OpenStreetMap

a short introduction

@tmcw + @aj_ashton / MapBox

OpenStreetMap is a free world map created and owned by volunteers.

'Created by Volunteers'

  1. GPS Traces
  2. Data Imports
  3. 'Armchair Mapping'*

*what we're going to do

Imports?


Yes! Some of the best data is government-generated and free. The US Census TIGER dataset makes up most of America?

So I should import X?


Maybe! Ask on https://bit.ly/osm-import

'Worldwide'

OpenStreetMap data rivals commercial providers. In some areas, it's more complete - and in some it's less. But unlike other maps, this one you can improve.

'Owned by Volunteers'

You can download the whole thing: planet.openstreetmap.org


Or just cities: metro.teczno.com

'Free'

Free as in: not only $0, but you can adapt it, download it, print it, and more.


Without asking for permission.

So OpenStreetMap is a free world map owned and created by volunteers.

What's in it?

Yes

  • Transport
  • Buildings
  • Rivers
  • POIs
  • Borders

No

  • Ratings
  • Opinions
  • Historical Data
  • Rasters

everyone sees the same map

the key to understanding openstreetmap: it's a single, global effort. not just a dumping ground for data.

Structure

  1. nodes, ways, and relations: primitive types
  2. tags: all data storage
  3. changesets: history

nodes are points

ways are lines & areas

made up of nodes

aka LineString and Polygon

relations are groups

a group of ways → a multipolygon

* no real GIS equivalent...

tags are data

the basic form of a tag:

key:value
amenity:cafe

so nodes, ways, and relations are the basic elements of OpenStreetMap, and each can have data attached to them via tags

one last thing

Changesets

are our version of history

a changeset is a group of changes


user tmcw changed way #1000, adding a tag and removing a node.

responsibility and reversibility


this answers the question of vandalism: yes, it happens, but we know who does it and we can reverse the changes

that is, everyone has an account