[OSM-dev] Max size of changeset with josm (in kb)

[Karl Newman]

On Sun, May 31, 2009 at 9:52 AM, Chris Jones <rollercow at sucs.org> wrote:

>
> On 31 May 2009, at 15:40, Sam Vekemans wrote:
>
> > Hi,
> > I already got part of the answer - 50,000 (things; nodes, lines, areas
> > -total) so now i want to know, what approx size (in mb, kb) is safe?
> > I loaded a changeset of 358 kb and it seemed happy. Would 1 meg be
> > too much?
>
> Size all depends on the volume of tags attached to the objects.
>
> > I know that there is a max geographical download area built in, (it's
> > say's "download area OK, size probably acceptable by server") but is
> > there a time out or an exact max file size to download? (a squak
> > level) (i know that i download a large area when im tracing from my
> > GPS Tracks.  (Victoria is about 8 megs) and so it takes a little time
> > to load, so i dont load that big area any more, i just open that old
> > Victoria file, then zoom to the area im working in, then get the
> > latest updates for that small area.
>
> There a limits (on the main api) on both area 0.25 degree squares and
> number of objects returned.
>
> See http://api.openstreetmap.org/api/capabilities
>
> > Also, is there an easy way i can chop the .osm file into 4 or 16 happy
> > geographical area chunks? Thus, smaller file sizes to deal with.
>
> Osmosis - http://wiki.openstreetmap.org/wiki/Osmosis
>

Be careful using Osmosis for this purpose. It's fine for cutting out one
area, but for cutting an input file into multiple adjacent areas, it's less
than ideal. You'll either get duplicate data (completeWays=yes) in adjacent
areas or incomplete/mangled data (gaps at the border). If you're going to
process the output offline, it's no big deal, but if you plan to upload it,
it matters.

Karl
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