[Talk-tz] Import of Tanga Building Footprints

[Innocent Maholi]

Hi Antidius and team,

Thanks for opening up communications about the data import intended for
Tanga and for sharing the link to the wiki page with the workflow. I'm also
adding a few other people to this email chain.

I have downloaded and checked the Tanga buildings data
<https://drive.google.com/file/d/1zzuKwMvZCK6_J-_HK8k2eH9KkaADyUrW/view?usp=sharing>,
this generally looks good and I’d like to congratulate everyone involved in
the digitization process however a few things stood out to me;


   -

   The use of 2019 imagery seems to be off for digitization as 2 years of
   difference can present outdated data that allows lots of differences with
   the current situation. Correct me if I’m wrong but I understand that
   ARU/dLab has access to 2021 drone imagery of Tanga which seems to be
   perfectly up to date for this work. Did you consider this option?
   -

   The data doesn’t show differentiation between “complete buildings” and
   “incomplete/unfinished buildings” even though the difference can clearly be
   visible (at least with the Bing imagery I have used). This is of interest
   for data users to understand and make considerations.


Now coming to the OSM data import, this is usually a complex process as it
needs to be properly conducted and reviewed with the assistance of more
technically oriented and experienced OSM editors to avoid data quality
issues and conflicts while keeping the OSM data at its best state. Reading
through the Tanga wiki page
<https://wiki.openstreetmap.org/wiki/Tanga_Building_Footprints_Import> you
established, here’s are a few (not all) comments;

   -

   There’s no clarity on the workflow between the building data you already
   created and the methodology to have this data in OSM. While the import
   type
   <https://wiki.openstreetmap.org/wiki/Tanga_Building_Footprints_Import#Import_Type>
   section talks about how the community will use the HOT tasking manager
   to import this data to OSM, the team approach
   <https://wiki.openstreetmap.org/wiki/Tanga_Building_Footprints_Import#Team_Approach>
   section suggests that “data import will be conducted by the *University
   experienced OSM mappers* through existing OSM project accounts
   (Living_Lab_Initiative)”. As this contradicts itself, does this data
   import neglect the broader OSM community and its contribution? Do the
   intended university students have (enough) experience with large-scale
   imports like this?
   -

   The use of HOT tasking manager as suggested isn’t quite captured in the “
   workflow” section. This part only mentions JOSM, OpenData plugin, ToDo
   plugin, and OSM only as the tools/platforms to be used for this import.
   This worries me whether there's a clear and understandable workflow to be
   used for this.
   -

   QA plans are not quite well established to ensure the good quality of
   the data. The wiki suggests that “Validation of the import will be done
   by a second user in the Tasking Manager”. Who is this second user? Is it
   global OSM contributors? Of what mapping level? Can they be trusted with
   QA? etc.

OSM guidelines suggest that “Take great care to avoid damaging the database
and don't leave a messy import and assume that nameless OpenStreetMap
contributors working in iD <https://wiki.openstreetmap.org/wiki/ID> and
Potlatch <https://wiki.openstreetmap.org/wiki/Potlatch> will tirelessly
complete your work. JOSM is better at untangling messy data, but it's still
difficult and you should do this work yourself if necessary.” Of all
things, QA should be given high priority to ensure good data.

   -

   Last but not least, this import should be registered in the import
   catalogue <https://wiki.openstreetmap.org/wiki/Import/Catalogue> as it
   is missing there right now.


My honest opinion is that this import is not quite ready to be executed
with the plan that is in place. The data is quite good and of decent
quality but the process does not ensure keeping OSM without risking the
data quality in the database. I'd appreciate hearing more thoughts from you
and the mailing list members.

Thanks and regards,
*----*
*Innocent,*
Phone: *+255 714 166 665* (Call & WhatsApp).


On Wed, Jun 2, 2021 at 9:08 PM Antidius Kawamala <antidius at dlab.or.tz>
wrote:

> Hello community,
> The subject of this message is to inform the OSM community in Tanzania
> of an import prepared by Living lab initiative as part of a project to
> scale up the Open Street Mapping project,Missing Maps Initiative by
> combining data obtained from manual digitization from the latest satelite
> image 2019 In Tanga City.
>
> This import consists of more than 500 hundred thousand footprints of
> buildings located in all over the Tanga region.
>
> A wiki page with details of the proposed import is available
> here: https://wiki.openstreetmap.org/wiki/Tanga_Building_Footprints_Import
>
> Experienced OSM contributors who would be interested in participating in
> this import will be welcome.
>
> A similar message regarding this import will also be shared on the OSM
> mailing list,HOT and WhatsApp group for OSM Tanzania after posting to the
> wiki to gather a maximum feedback.
>
> Don't hesitate to share your comments, questions, or problems
> related to this import before it begins.
>
> Regards
>
> *Antidius Kawamala*
> *GIS Specialist and **Researcher (dLab)*
> *M: +255769806836*
> *Founder of **RootGIS <https://rootgis.wordpress.com/>*
> *Skype: Antidius Kawamala | Twitter: @Antidius36*
> *P.O. Box 33335 Dar es Salaam, Tanzania | College of ICT, UDSM-
> Kijitonyama campus | **dLab <https://dlab.or.tz/>*
>
>
>
>
> _______________________________________________
> Talk-tz mailing list
> Talk-tz at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-tz
>
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