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

Jean-Guilhem Cailton jgc at arkemie.com
Fri Apr 4 20:10:48 UTC 2014

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,


Le 04/04/2014 21:05, Michael Judex a écrit :
> Dear all,
> I'm just starting to map roads etc. for this job with the SPOT-6
> imagery in NIR. The already existing major roads have a significant
> offset to the satellite image (e.g. major road from Macenta to
> Voinjama). Should the offset be corrected or is the geometric
> correction of the SPOT images not sufficient?
> thanks,
> Michael
> Am 04.04.2014 15:26, schrieb Jean-Guilhem Cailton:
>> Hi,
>> Airbus Defence and Space, Geo-Intelligence has donated Spot-6 images,
>> acquired between 2013-10-13 and 2013-12-11, that cover a large part of
>> the area of the border between Northern Liberia and Southern Guinea,
>> including the towns of Voinjama and Kolahun in Liberia, as well as the
>> cities of Guéckédou and Macenta in Guinée, and their surroundings.
>> Job 489 has been set up on the Tasking Manager:
>> http://tasks.hotosm.org/job/489
>> For the cities of Guéckédou and Macenta, where higher resolution
>> Pleiades images are available and that were already mapped (jobs 469 and
>> 471), it is better to keep using the Pleiades images as geometrical
>> reference, as they have better accuracy (6.5 m CE 90 without GCPs).
>> Use source=Spot-6, Airbus
>> Best wishes,
>> Jean-Guilhem
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