[HOT] Spot-6 images of Guinée / Northern Liberia available, job 489

Michael Judex m.judex at gmx.de
Sat Apr 5 19:25:52 UTC 2014


Thanks for the answer! I've another related question/issue: There is a 
systematic geometric shift between SPOT-6 images of task 489 (Guinée / 
Northern Liberia border area) and Pleiades-1A images of task 471 (only 
for the town of Macenta, which is included geographically in 489). I 
think that an offset of 10.44; 14.24 (in JOSM) for the SPOT-6 images is 
good to have a proper fit to the Pleiades images.

So my questions are:
- is the geometric accuracy of the Pleiades better than SPOT-6? (I 
assume yes)
- do we then have a systematic geometeric distortion in task 489 for the 
edits that relied only on the SPOT-6 imagery? If yes can we correct 
this? (maybe the the only way to really fix offsets between different 
images are GPS ground control points...)

I think it could be helpful to have an instant overview of ALL available 
imagery for a specific area. If a mapper opens a task only the dedicated 
imagery is listed in the task instructions. Is there a simple way to 
achieve this?

Thanks for your support!

Michael



Am 05.04.2014 11:19, schrieb Pierre Béland:
> Great. Thanks both.
> Pierre
>
> ------------------------------------------------------------------------
> *De :* Jean-Guilhem Cailton <jgc at arkemie.com>
> *À :* Michael Judex <m.judex at gmx.de>; hot at openstreetmap.org
> *Envoyé le :* Vendredi 4 avril 2014 22h10
> *Objet :* Re: [HOT] Spot-6 images of Guinée / Northern Liberia 
> available, job 489
>
> Hi Michael,
>
> The existing roads were probably based on Landsat, the geometric
> accuracy of which is lower than Spot-6. So if you feel that adjustment
> is needed, the pre-existing road should probably be adjusted. This would
> also make it possible to have a consistent geometry for tracing streets
> and buildings within villages and towns.
>
> Best wishes,
>
> Jean-Guilhem

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