[HOT] data alignment to satellite imagery

Pierre Béland pierzenh at yahoo.fr
Mon May 4 12:23:39 UTC 2015

Hi Michael,
It would greatly help us if people who have trekked in these areas send us gps traces. These long paths woud be useful, plus village names.
I sent a twitter yesterday to sollicit receiving these gps traces. People should write to activation @ hotosm.orghttps://twitter.com/pierzen/status/594786000729186304

      De : Michael Krämer <ohrosm at gmail.com>
 À : "HOT at openstreetmap.org" <hot at openstreetmap.org> 
 Envoyé le : Lundi 4 mai 2015 2h56
 Objet : Re: [HOT] data alignment to satellite imagery


for me the "gold standard" for image alignment in OSM are gpx traces with high quality. If no traces are available - which likely applies to most of Nepal - Bing is the standard to use. In either case adjust any other imagery to match the alignment of the standard.

But now the limitation: Some of the imagery currently in use with HOT shows some difference compared to Bing. But this is not a simple shift. To my limited understanding this comes from the correction applied to the image. Especially in mountains this is difficult - which likely is especially true for the Himalayas. But keep the distances in mind: With high resolution images a shift of let's say 10 m is pretty visible - but should not really matter too much in real live.

In any case: Try to align any of your work with Bing. Leave any misaligned data for now.

Michael (user Ohr)

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HOT at openstreetmap.org

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