[OSM-talk] Historical Data in OSM database
davey at incanberra.com.au
Wed Nov 10 22:31:06 GMT 2010
On Wed, 2010-11-10 at 22:25 +0100, Laurence Penney wrote:
> For the record, I'm 100% against OSM becoming a place for general
> historical data ...
Just out of interest, are you 100% against OSM keeping recent history
data? If a building is demolished, do you believe that deleting the way
should remove any trace of that from OSM, or do you believe that OSM
should retain a history? How long should that history be retained? In
10 years, would you advocate that any historic data (objects deleted
over n years ago) be deleted, to avoid cluttering the database? If OSM
had existed 20 years ago, would you be advocating that the database be
kept clean, so that only current data is in it?
OSM, by its nature, is excellent for retaining historic data, for
example if a road is realigned, you have a history that shows how it was
realigned, or if a road changes name, there exists a history of previous
> I'm not sure what you're saying - that 18,000 tag usages is
> insufficient for someone to try to sort out a mess of tag values?
I read it more as 'this tag already has a range of values and other
uses, do you really have to use it?'. You also have to wonder, of those
18,000 tags, how many are in your area of interest, and what percentage
of nodes in that area are tagged? Maybe .1% if youve been busy.
> On 10 Nov 2010, at 21:40, Richard Weait wrote:
> > On Wed, Nov 10, 2010 at 2:51 PM, Laurence Penney <lorp at lorp.org> wrote:
> >> It would be good to have consistency in the start_date value. Taginfo reports 18313 usages (2814 distinct), of which these are examples of values other than simple 4-digit years:
> > [ ... ]
> >> So it's clear there's a demand for: exact dates; general approximations; approximations to the month, season, century; before <date> and after <date>; early <period> and late <period>, maybe also mid <period>; date ranges; multiple values; BC and AD.
> > There may be a "clear demand" or interest in start_date, but it is a
> > limited one based on your measurement of 18k appearances in the data
> > base.
> > There are also 18k instances of amenity=waste_basket,  28th in
> > amenity and 18k instances of highway=stop  28th in highway. Both
> > waste_basket and stop are clearly defined and are likely to reflect
> > only one specific thing.
> > By comparison, start_date, may well be used to note the construction
> > date or commissioning date of a bridge, but might also define the
> > seasonal hours of a tourist attraction only open during the summer.
> > Only one of these supports your assertion. I would argue that
> > start_date, for your specific "beginning in an historical sense" use
> > is much less prevalent in the data base than you suggest and that
> > there is much less "clear demand" for an historical start_date than
> > 18,000 appearances might suggest.
> > That said, I find the idea of OpenHistoryMap to be a curious idea. I
> > think the idea has potential interest to historians, students,
> > developers, genealogists and others. But I also think it is
> > orthogonal to OSM. If you find the OSM stack helpful in creating
> > OpenHistoryMap then do so. It sounds to me like a Really Big Job
> > though. Not the work of just a weekend.
> > But go for it. Build it based on the OSM stack. If it can be done in
> > a way that keeps OpenHistoryMap contributors happy, and doesn't break
> > OSM tools downstream, it might be considered for merging into some
> > future OSM. Even if it does break downstream OSM tools, you'll still
> > have a working OpenHistoryMap, and will have had a leg up from
> > starting with the working OSM stack.
> >  http://taginfo.openstreetmap.de/keys/amenity
> >  http://taginfo.openstreetmap.de/keys/highway
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