[HOT] Keeping the data consistency when updating an area with a new imagery

nicolas chavent nicolas.chavent at gmail.com
Sun Jul 6 14:07:38 UTC 2014

Thanks Severin for turning the contents of this Burkina Faso workshop into
those structured wikipages.

On Sun, Jul 6, 2014 at 3:06 PM, Severin Menard <severin.menard at gmail.com>

> Hi,
> When we get recent imagery over areas that have already been mapped with
> Bing imagery, very often it does not have exactly the same georeferencing,
> and very often we do not have any trace or not enough to fix this.
> Consequently, either the contributor will offset the new imagery on the
> vector data, or on the contrary will move the vector data. It results the
> map becomes less consistent it was before.
> To solve this, when partnering with GISCorps to map Malakal
> <http://tasks.hotosm.org/job/413> in South Sudan, I had created a grid of
> offset correction points with the great offset_db plug-in for JOSM
> <http://wiki.openstreetmap.org/wiki/Imagery_Offset_Database> so that
> every contributor could, in two clicks, get the new imagery aligned on the
> Bing imagery, easily update the data and keep the data consistency. It
> worked really well.
> As we will get more and more access to recent imagery, my idea was to find
> a way to repeat this without relying to the previous action of a single
> person and spread the use of the offset_db plugin. Recently, in a workshop
> with various contributors in Burkina Faso, I tested a workflow involving
> the Tasking Manager and it worked also well.
> Next step is now to involve the crowd to this process. I created an OSM
> wikipage both in French and English (any correction by native speakers
> would be appreciated) :
> http://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager/Offset_db
> and created a job for Bossangoa (http://tasks.hotosm.org/job/578) in
> Central African Republic, because our partners from the HIU kindly provided
> a recent NextView Imagery.
> Once you catch the workflow, you will see it is really quick to create
> offset corrections points and the outcome (the data consistency) are really
> substantial.
> Please join!
> Sincerely,
> Severin
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Nicolas Chavent
Humanitarian OpenStreetMap Team
Mobile (FRA): +33 (0)6 52 40 78 20
Email: nicolas.chavent at hotosm.org
Email: nicolas.chavent at gmail.com
Skype: c_nicolas
Twitter: nicolas_chavent
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