[HOT] GAP Analysis or Regional OSM Mapping Assessment

Rafael Avila Coya ravilacoya at gmail.com
Mon Jun 22 21:36:20 UTC 2015


Hi, Samuel:

I've actually seen this email a couple of days ago, but didn't have time
to answer. I am also sorry for the delay.

As Russell says, unless we have another database to compare against, I
can't see a reliable way to get an estimate of the completion percentage
of roads already mapped and those still missing (but that doesn't mean
there aren't!). The only database I know of is the GRoads one [1], but I
think Kano state has already more roads mapped that GRoads, and probably
any other map. But this idea could be applied to the poorly mapped
Central and South Nigeria.

Séverin Menard has opened at least two projects in the TM to complete
the road network taking GRoads as a reference, one for Mali [2] and
another for Central African Republic [3]. The goal is not only to
complete the road network, but also to timestamp all segments using
Bing/Mapbox imagery. I think this idea could be used in Nigeria too, at
least for those still-poorly-mapped states.

Kano state road network was mapped through a TM job [4] about a year
ago. In my honest opinion, I wouldn't use that same job for validation,
but I would rather create a new one to validate, with less and bigger
task tiles. As I have been mapping hard that area, I give you my
opinion: the number of roads and tracks for Kano state is quite high
already, but you can find some settlements here and there that aren't
connected. Also, some tagging should be corrected (add surface to some
highways, and correct the category of others).

The main purpose of a road network is to connect all settlements in an
area. For that reason, I think the new jobs of importing health
facilities and settlements for Borno State [5]]6] is giving better
results. The reason is that in those two projects, contributors are
asked to map the road access to all those health facilities and
settlements, making the task more comprehensive and consistent, as they
will have to make sure they don't leave any settlement nor health
facility behind. I have still to do some more validation in those two
projects, but my understanding is that they are giving better overall
results. I had already this idea when the Kano project was going on, but
there were too many things to do at the same time, unfortunately.

Cheers,

Rafael.

[1]
http://sedac.ciesin.org/data/set/groads-global-roads-open-access-v1/data-download
[2] http://tasks.hotosm.org/project/813
[3] http://tasks.hotosm.org/project/783
[4] http://tasks.hotosm.org/project/474
[5] http://tasks.hotosm.org/project/946
[6] http://tasks.hotosm.org/project/937

On 17/06/15 12:03, Samuel Aiyeoribe wrote:
> Hello House,
> 
> I would like to know if there is a way, tool, method or any service that
> one can you to assess the amount of mapping that has been done for a
> region so as to plan further mapping. For example, i want to plan how to
> complete road mapping on OSM for Kano State, Nigeria, is there any tool
> or service or method i can use to assess the amount of work has been
> done already for Kano? Simply put may be any service that can give
> statistic of percentage completion or summary of work done  for road or
> other features to be mapped.
> 
> I understand there is a similar service on Task Manager but i need such
> from the OSM database side because on Task Manager, one can create
> multiple tasks for e.g Kano which does give you the true picture.
> 
> Will be expecting your assistance.
>  
> Samuel Aiyeoribe
> 
> 
> 
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> 

-- 
Twitter: http://twitter.com/ravilacoya

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