[osmosis-dev] planet diff to polygon extract?

[Brett Henderson]

On Wed, Dec 30, 2009 at 3:56 AM, David Carmean <dlc at halibut.com> wrote:

>
> For the moment I'm working with just the Cloudmade California extract
> (in PostGIS simple schema).  Is it possible to perform a polygon
> clip/extract of the daily planet diffs (changefile)?  Failing that,
> what happens if a planet-wide diff is applied to an incomplete
> planet base file?
>

You can't perform a polygon extract of a diff file (the diff file doesn't
contain enough info to determine the location of ways whose nodes haven't
changed).  However you can perform a polygon extract on the merged result.

In other words:
1. Apply the full diff to your extract first.
2. Run the result through the bounding polygon task again with the
California coordinates.

You can do it all in a single osmosis incantation if necessary.  Something
like:
osmosis --read-xml-change diff.osc --read-xml california-orig.osm
--apply-change --bounding-polygon file=polygonfile.txt --write-xml
california-updated.osm


>
> Also curious: how much diskspace does the postGIS simple schema
> use for a complete planet file?
>

I have no idea ... lots :-)

Brett
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