[HOT] Hot Job 591 Cholera in Juba - Bing imagery updated, new offset

[Severin Menard]

Hi Dietmar,

Indeed the Bing imagery has been updated and is now from June 2013, what is
older than the WorldView2 imagery from http://tasks.hotosm.org/project/591,
but with a better resolution. As many people will use Bing and not the WV2
imagery because they do not know about the job, it is worth to consider
Bing as the reference knowing that Bing has good georeferenced imagery
except in a few places (seems Manilla).
I checked the current map and there is a general offset for buildings and
walls, while I know roads were not always correctly traced everywhere.
Currently realigning the buildings and walls on Bing as a batch, the
process should be achieved in a few hours.
I would recommend (I will update the job instructions accordingly) to:
- align WV2 on Bing
- check the differences between WV2 and Bing where you trace and
- where there is no difference, trace on Bing (better resolution)
- where Bing is outdated, trace on WV2

Sincerely,

Severin



On Thu, Aug 21, 2014 at 10:12 PM, Dietmar Seifert <ostrmap at diesei.de> wrote:

> Hello,
>
> it seems, that the bing imagery in some areas of africa has been
> updated, according to [1].
>
> In Juba (Job #591), the bing imagery were updated, too. They are now in
> the city area from 2013.
>
> The problem is, that the bing images now have an other alignment than
> the older ones.
>
> Buildings, that i mapped one or two weeks ago and which i mapped with a
> mix of bing and the "Digital Globe’s WorldView-2 satellite taken on
> February 20" images (later ones i aligned to bing images as the task
> text describes), appears now with the bing images between 5 and 10m in
> wrong position.
>
> The mapped buildings with such an offset should be no problem in field,
> but i don't know, how to proceed with working the neighbour tasks. Which
> imagery should be now the reference?
>
> I took a few tasks last weeks and in every case, i found alignement
> differences from old bing imagery to digitcal globe imagery within 2m in
> both directions.
>
> Now with the new bing images, i have bigger differences.
>
> How to proceed with working on the tasks and should the task text be a
> little bit updated?
>
> Greetings
>
> Dietmar aka okilimu
>
>
> [1] http://www.openstreetmap.org/user/naoliv/diary/23577
>
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