[OSM-talk] On how to store geospatial data !?;

[Martin Spott]

Hello Nick,

"Nick Black" wrote:

> Could you post us some more information about how people can access the
> datasets?  Is there an API or some other method to get hold of the data that
> you have?

Well, the easiest way to distribute the data is to provide Shapefiles
or PostGIS dumps of the data. PostGIS is certainly best for users of
the PostgreSQL/PostGIS data storage (which I highly recommend),
Shapefiles are sort of the "Swiass Army Knife" for exchange of
geospatial vector data. FlightGear scenery tools "TerraGear" started
using Shapefiles for input last year. I'm creating these dumps
occasionally, depending on if someone needs them.

What we're aiming at is WFS-T, a method to read and write geospatial
data in the so called GML (Geo-XML) format. As an example you can
retrieve the geographic location of a single airfield (ICAO: EDWJ)
using a simple HTTP URL as an analogy to a similar SQL statement via
WFS (very long URL !!):

  http://flightgear.telascience.org/cgi-bin/landcover_wms?Service=WFS&Version=1.0.0&request=GetFeature&Typename=airfield&MaxFeatures=10&Filter=<Filter><PropertyIsEqualTo><PropertyName>icao</PropertyName><Literal>EDWJ</Literal></PropertyIsEqualTo></Filter>

As you can see, a WFS-service is already running but we're yet working
on making this service ready for common use.

At this point one of the major differences between OSM and OGC, which
my repository tries to base on, becomes obvious. OSM decided to create
their very own data model and start really early with building and
providing tools for editing. The OGC folks started by researching,
defining and implementing a standard for storage of and universal acces
to geospatial data, so the development of tools that let everyone alter
the data is a bit behind. They do exist say in the form of QGIS and
uDig for example, almost every modern GIS tool is able to read from
WFS, but, as the name says, these currently focus on GIS folks and not
the common user. Tools for the average user will show up in the not so
distant future - it is expected that users of the FlightGear flight
simulator will contribute significantly in the long run.


> With regards to the aims of OSM, they are simply to create a free map of the
> world.  The exact direction that this takes is determined by the community,
> who may focus on creating pretty maps, or routing (don't think anyone has
> done this yet), making maps for GPS units, analysing data etc.

Well, my goals somehow cover these areas. At least I'm trying to keep
the repository in a shape that it fulfills these goals as well. I think
currently accuracy on one side stands against coverage on the other
side. It would make a really big deal if we'd manage to benefit from a
combination of these advantages.

Cheers,
	Martin.
-- 
 Unix _IS_ user friendly - it's just selective about who its friends are !
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