Re: distance vector databases and country maps

Hi,

I believe postgresql has polygon, box, circle etc datatypes which could be
useful in your situation. Depending on how you are doing your maps the
world being approximately spheroid may or may not be a consideration in how
you approach things (to avoid 2-D wraparound issues for instance).

Datatypes
http://www.postgresql.org/idocs/index.php?datatype-geometric.html#AEN3665

Operators/functions to use with those data types.
http://www.postgresql.org/idocs/index.php?functions-geometry.html

e.g.
Operator: @
Meaning: Contained or on
Usage: point '(1,1)' @ circle '((0,0),2)'

Indexes
http://www.postgresql.org/idocs/index.php?indices-types.html

CREATE INDEX name ON table USING RTREE (column);

I haven't any experience in using these features but I figure they might be
helpful to you.

Cheerio,
Link.

p.s. Yeah Postgresql is also copyrighted, but it's BSDtype :).

At 05:33 PM 10/6/01 +0200, you wrote:
>I am looking for info on free/open source (or if that's not available,
>any other product) products which can be integrated with PostgreSQL that
>provide geometric vector data on geographic maps.
>
>In particular, I need that for Germany. What I want to do is to find
>cities within a 50-100 km radius of any given location on the map. I
>know that quite a few people are working on this and that such solutions
>exist; I just don't know where to start looking. Also, my impression is
>that all of these solutions are heavily copyrighted, patented etc. and
>that it's probably really expensive to get to use this kind of data.
>
>Can anyone help out with info, starting points?
>
>Thanks, Frank
>
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