[HOT] OpenStreetMap data, good and bad

john whelan jwhelan0112 at gmail.com
Tue Nov 15 19:13:29 UTC 2016

Looking at the other half there are only 3,000 untagged ways.  In general
it doesn't look too bad but yes there are some areas that might not meet a
desired standard.

I think the problem is three fold, first experienced mappers who map as
they would in Europe without regard to the
http://wiki.openstreetmap.org/wiki/Highway_Tag_Africa or the convention
that huts should be mapped as an area rather than a node.  These aren't a
major problem as the quality is otherwise fairly good.

Second mapathon or inexperienced mappers not knowing what they are doing.
Validation helps here if you give them feedback you get more out of them
and its better quality but you need a validator who knows what they are
doing and don't even try and validate in iD.  One major difficulty is that
many new mappers will not finish a tile which makes their work more
difficult to spot when validating. If you can ask them nicely to map from
the top then it gives someone a chance to go over their work without having
to scan the entire project.

However we don't have enough validators, especially ones who can give
feedback without turning the mappers off.  To be honest when faced with
another seventeen new mappers sixteen of which you know will probably only
map once validating their work isn't that rewarding and its faster to map
it yourself than to do a full validation feedback.

http://tasks.hotosm.org/project/1396# is an example of a validated
project.  We still get new mappers and mapathons on there but the quality
isn't too bad.  We also have a pair of very nice mappers who cleans up
tiles that have been marked invalid because they're incomplete.

http://tasks.hotosm.org/project/1087 is another project that gets a lot of
validation, its big but at the moment it seems to have attracted the
attention of a local mapper and developing local expertise is always a good

I think the third cause in Africa is the variety of local languages used,
they aren't all supported in the training guides and wiki.  Local mappers
are not supported as well as they could be.

Training helps, but not every mapathon has it nor do all the organisers
know much about OSM.  Projects that are limited ie buildings or highways
and settlements mean there is less information to absorb by new mappers.

Cheerio John

On 15 November 2016 at 08:26, john whelan <jwhelan0112 at gmail.com> wrote:

> Looking in JOSM at half Tanzania there are some 4,000 untagged ways,
> 26,000 duplicated nodes etc.
> I'll take a look over the next few days.
> Cheerio John
> On 15 November 2016 at 01:12, Douglas Ssebaggala <
> douglas.ssebaggala at hotosm.org> wrote:
>> Dear community members,
>> While at the spatial data workshop <http://i2ifacility.org/Spatial_Data/>
>> a few days back in Tanzania, there was unique feedback from some of the
>> people and organisations who have used OSM data: they greatly appreciated
>> the quality of the data in OSM: buildings, roads, and business information,
>> e.t.c thanks to the Ramani Huria team, and community members who are doing
>> the mapping.
>> This data is being used <http://www.worldpop.org.uk/> for analysis,
>> insight generation and maps!! However, the need for more quality data was
>> also echoed as a very important aspect needed in all these efforts.
>> A while back there was a discussion on new mappers, and generally making
>> wrong edits to OSM, especially during need for maps and data in critical
>> situations: considering that *mapping for flood resilience* scaled to
>> involve *new* community members/*mappers* whose data is now proving
>> *usefu*l, and good quality, i think we should always guide, understand,
>> and help out any new mappers who might make mistakes, as with time their
>> contributions will be helpful.
>> --
>> *Humanitarian OpenStreetMap Team
>> *Mapping Supervisor "Financial Services", Uganda
>> Email: douglas.ssebaggala at hotosm.org
>> Skype: douglo.m
>> Twitter: @douglaseru <https://twitter.com/douglaseru>
>> UG Mobile: +256 772 422 524
>> *Using OpenStreetMap for Humanitarian Response & Economic Development*
>> web <http://hotosm.org/> | twitter <https://twitter.com/hotosm> | facebook <https://www.facebook.com/hotosm> | donate <http://hotosm.org/donate>
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