[OSM-talk-be] more stats: data density in the Belgian regions

[joost schouppe]

Marc,

I really have no experience handling snapshots or changesets. I wouldn't
mind digging in, with some guidance though. Hackathon, anyone?

Anyway, in my processing, there's a phase where I parse quite a few tags.
It wouldn't be hard to create a file which aggregates these tag
changes/additions by users. When you have a file like that, you could take
any spreadsheet editor and select just those users that have worked on
subjects that interest you.

About map completeness: yes, sometimes external sources are nice. For
example, road network length is available in the CIA factbook. But for a
thing like a road network, assessing completeness can be done entirely with
OSM data: in a graph like this one http://i.imgur.com/2hxAXNk.gif you can
clearly see that the main road network is complete, but that we have a lot
of work left to map "slow roads". Of course, that only works if sufficient
people are working on something. For example, the same graph in Bolivia, or
the number of monuments in Flanders might not allow for such statistical
decisions on completeness because too few people are working on them. The
same with imports.
In the case of landuse, it should be simple: if total mapped landuse
approaches total area, you're there. But it's complicated, as polygons
overlap each other all the time. So some GIS processing would be in order
to decide on that. (I haven't found out how to do that in Postgres yet)
Of course, this kind of "completeness" measurements are always changing.
Once all the ways of a road network are there, there are still a million
details left to map. You could then plot the evolution of pedestrian
crossings; or the percentage of roads mapped with maxspeed. (this I do know
how to do)

So I don't think things that are "complete" will actually be mapped less.
Imagine a map with all POIs mapped. POI related mapping might actually
increase, with things like opening hours and websites becoming more
relevant as data use increases.

Another conclusion: unless you have external sources to compare to, you
need to look at history, not snapshot, to assess completeness.

2015-11-10 17:31 GMT+01:00 Marc Gemis <marc.gemis at gmail.com>:

>
>
> On Tue, Nov 10, 2015 at 8:17 AM, joost schouppe <joost.schouppe at gmail.com>
> wrote:
>
>>
>> As to the thing you want to do with similar mappers: does it have to be a
>> history file? I'm not sure, and if it isn't, it's probably easier to do it
>> on a snapshot. That would make regular updating also easier.
>>
>
> On a snapshot is fine. No need to find who was mapping the same as me.
>
>
>
>
>> That said, I can release some of my intermediate files as tables or csv,
>> someone might be able to make some kind of website out of that. But that
>> would again be with a local scope, as I don't have the capacity to process
>> global files at once. (I cut up the world in little pieces to run analysis,
>> but that means you need to finish a processing script before rolling it
>> out, and I'm not good at finishing things)
>> Some of the questions you asked have little to do with local context, so
>> it might be more interesting to see how a thing like taginfo works and
>> build upon that.
>>
>
>  There national versions of taginfo for France and the UK. That is, they
> only look at the tags in 1 country.
>
>  I saw all my questions in local, Belgian context. E.g. is there someone
> else mapping heritage buildings in Belgium, or am I the only one ? If not,
> we could get in touch and exchange ideas specific for Belgium. (or Flanders
> or ...)
>
>
>
>>
>> My personal interest is more about "map completeness" for road networks,
>> landuse, amenities, etc; with a global scope. In the second place mapper
>> inequality and remote mapping. For things like that, I don't see another
>> approach than taking world history and cutting it in pieces...
>>
>>
>
> Do you compare with an external source, or is something complete when less
> mappers are mapping it now compared to "yesterday" ?
>
> My first interest is what are we (the Belgian community) mapping now. This
> is somehow related to your "map completeness", something that is complete,
> will no longer be mapped. I'm looking forward to see what you mean with
> complete :-)
>
> regards
>
> m
>
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