[OSM-dev] {To Brett} Re: OSM Data Question from FireGirl

Fire Girl firegirl at amorous.com
Wed Feb 13 05:02:53 GMT 2008


  Firstly you need to figure out what you want to do with the data :-)
  That will help limit your options. You'll need to determine things
  like:
  1. How many different areas do you need?
  2. How large are the areas that you need?
  3. How up-to-date does the data need to be?

  If you're pulling out many different areas at regular intervals then
  something like osmosis will give you a lot of flexibility. If you
  need
  a specific area that isn't *too* large, osmxapi will be the simplest.
  If up-to-date data isn't critical then a pre-generated extract may be
  more appropriate.

  In general, large amounts of data are best served by osmosis. With
  osmosis you can slice and dice to your hearts content without
  consuming
  server resources (other than the initial planet download). Very small
  areas may be served by the standard osm api but try to limit your
  usage
  of this. Somewhere in between lies osmxapi which will handle larger
  areas than the main API, but probably not ideal for downloading whole
  countries.

  The main API will provide the most up-to-date data, osmxapi will be
  within 10 minutes, and osmosis just works with whatever files (ie.
  planet file) and changesets (ie. daily/hourly/minute) you choose to
  download but can also be within 10 minutes with a bit of effort.

  If you're just trying to get used to OSM and don't know what you need
  yet, I'd suggest downloading one of the extracts suggested by Milenko
  (http://planet.king-nerd.com/usa/) and playing with it. When you get
  something working using that data then you can figure out how to get
  your updates to that data.




Ah thank you Brett... I think this is leading me down the right path. :)
Basically, yes, I am looking for a Pre-Generated extract and just plan to
use the OSM data for in-house rendering (don't need to serve it up). So
given that fact, it sounds like osmxapi - is the way to go to get to
specific tailored OSM data files?  I am a Windows girl, but can setup
Linux with some effort ... but maybe you know a way to do this in
Windows.  I've got a pretty souped up box and that would be ideal for me.

One thing I noticed is these OSM files, ..... even State files are very
huge.  They sit in a compressed BZ2 format like at 50MB for a state...
but once you fluff it up, it grows to over 1GB for just one single State.
........ Can the data within these compressed files be extracted for what
is needed without fully un-compressing it.... or *must* you un-compress
it.  I guess that is a stupid question perhaps, but just checking.

finally... what is on my mind is, let's say I need to get to just a very
small geographic region, a Neighborhood within a City within a State for
example.  To extract the OSM file for a City, I need BBOX coordinates,
correct?  If that is the case, what is my best bet for getting to the
BBOX (I hope I am using the correct nomenclature), to finagle the
SOME_CITY_DATA.OSM file (for instance) from a SOME_STATE_DATA.OSM file? 
Using osmxapi first against the STATE OSM file that contains the CITY i
am interested in? :)

Am I on the right track in my thinking here?

**** Summary *****

LOGIC: >> STATE OSM FILE (1GB) > COULD POTENTIALLY EXTRACT INTO 100'S OF
CITY OSM FILES USING OSMXAPI

QUESTION: IS OSMXAPI THE FASTEST WAY TO JUST GET FIXED DATA FOR IN-HOSUE
RENDERING, NON-SERVER USE?

ALSO: IS THERE A WINDOWS PATH TO GETTING TO THIS LIMITED DATA?

AND FINALLY: HOW TO NAVIGATE RELIABLE BBOX COORDINATES, I presume to feed
into OSMXAPI to get to smaller Sub-Set data files for Cities or smaller
areas :)

Have a very nice evening.
Best wishes, FireGirl.

-- 
Want an e-mail address like mine?
Get a free e-mail account today at www.mail.com!

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/dev/attachments/20080213/13d3ec88/attachment.html>


More information about the dev mailing list