[OSM-talk] [OSM-legal-talk] Yahoo and OSM

Martin Spott Martin.Spott at mgras.net
Fri Mar 30 15:21:05 BST 2007


Robert Scott wrote:
> On Friday 30 March 2007 14:27, Martin Spott wrote:

> > Good aerial imagery is taken using markers placed at predefined ground
> > locations _plus_ a very good GPS _plus_ gyroscopes that allow you to
> > determine the pitch and bank angle of the aircraft. Additionally you
> > should have a radar altimeter that allows you not only to determine the
> > displacement of images against GPS location that occurs due to pitch
> > and bank but also delivers the required altitude information in order
> > to correct the deformation that you get by projecting the image onto
> > the terrain.

> It looks like my assumption that standard rubbersheeting and enough control 
> points would be able to sort out this problem was rather optimistic.

Not necessarily. I don't want to discourage anyone to spend some
thoughts on this approach, I'd just like to make clear that this might
turn into a challenging task - and, finally, the amount of effort alias
money you have to spend for it always depends on the accuracy you want
to achieve.

Flying, even in a 'simple' Cessna, proves to be an expensive adventure
nowadays if you have to pay for it out of your private budget.
Therefore I'd like to encourage people to make a really "good plan"
(TM) before they spend hundreds of Euros for getting into the air and
return with pictures of no practical use. If you're fluent in GRASS and
have lots of time to manually rectify and paste images together, and
'moderate' accuracy is sufficient, then this approach might turn into a
project that returns very much fun for every participant  :-)

Cheerio,
	Martin.
-- 
 Unix _IS_ user friendly - it's just selective about who its friends are !
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