[OSM-dev] Augmented Diffs

[ikonor]

Hi,

I'm still working on a change viewer based on OpenLayers using some sort 
of augmented change files [1]. The format currently used is simply 
extending the original osmChange with an 'augment' "action" at the end 
of the file that contains all the old versions and referenced objects.

While the idea is to get the augmenting data from a local extract before 
applying a regular diff, your augmented diffs might also be a good 
source for this. I especially have a live edit viewer in mind, that 
would not only show edited nodes but also ways and possibly relation 
changes.

Therefore, it would be nice to also get the nodes of ways with no 
geometry changes (tag changes only), to be able to show them on a map. 
Consumers can still distinguish geometry from tag only changes by 
comparing the old and new versions.

For relations, it might be a compromise to only include objects of 
changed members (added, removed, role change). Created and deleted 
relations would include all members. This probably would allow to 
display changes, to update route length calculations and the like 
without storing geometries and to update stored geometries, e.g. for 
multipolygon validations. Not sure what to do about relation tag changes 
though (the restaurant example).

Norbert

[1] 
http://gis.19327.n5.nabble.com/Useful-post-bot-visualisation-tt5716898.html#a5717002