[OSM-dev] Representing differences between sets of OSM data

[Martijn van Oosterhout]

On 8/20/07, Brett Henderson <brett at bretth.com> wrote:
> What are the reasons for attempting to use a common format?  Might sound
> like a stoopid question but I'm curious what applications people have in
> mind at this point.  At this point I'm not convinced that JOSM changes
> should be represented in the same way as planetdiff/osmosis change sets
> but I'm still undecided on the best approach.

Well, here is my use case (the reason why I brought all this up):

The AND data for NL needs to be merged with the current data. However,
not everything we currently have is in the AND data and viceversa.
Plus we also want to preserve some areas (ie. not remove them).

Now, I have script to cut out NL from the planet, and a script to
determine what needs to be deleted (for reference we'll be deleting
around 150,000 nodes, 180,000 segs and 30,000 ways). What I would like
is that output for the last stage to be something I can apply to
somewhere. The question is what format. We have:

JOSM format: currently only supported by JOSM, easy to generate. But
the change file is nearly 50MB and I don't have enough memory to load
this into JOSM.
planetdiff format: supported only by planetdiff. AFAICS it requires
the diff to be "sorted" which my script won't do.
osmChange format: supported only by osmosis. It may be the most
flexible of the lot, but it won't work for planetdiffs.

What I really want is two things:
1. From a given change file, apply it to a set of OSM data so I can
see the results
2. From a given change file, be able to apply it to the server

JOSM gives me 2 (assuming I had enough memory). osmChange gives me 1.

The reason I'm asking is that it would be simpler if there was a
format which could be well supported and be appropriate for most
people. I don't particularly care which, and I wanted to know whether
other people had any preferences.

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/