[OSM-talk] Three-dimensional aerial imagery

[Laurence Penney]

For how it was done in the 1940s, UK OSMers may wish to turn on the telly NOW!

http://www.bbc.co.uk/programmes/b011cr8f

Operation Crossbow
NEXT ON: Today, 21:00 on BBC Two (except Northern Ireland (Analogue), Wales (Analogue))

SYNOPSIS: The heroic tales of World War II are legendary, but Operation Crossbow is a little known story that deserves to join the hall of fame: how the Allies used 3D photos to thwart the Nazis' weapons of mass destruction before they could obliterate Britain. This film brings together the heroic Spitfire pilots who took the photographs and the brilliant minds of RAF Medmenham that made sense of the jigsaw of clues hidden in the photos. Hitler was pumping a fortune into his new-fangled V weapons in the hope they could win him the war. But Medmenham had a secret weapon of its own, a simple stereoscope which brought to life every contour of the enemy landscape in perfect 3D. The devil was truly in the detail and, together with extraordinary personal testimonies, the film uses modern computer graphics on the original wartime photographs to show just how the photo interpreters were able to uncover Hitler's nastiest secrets.

- L

On 15 May 2011, at 00:19, andrzej zaborowski wrote:

> On 14 May 2011 18:16, Ed Avis <eda at waniasset.com> wrote:
>> I saw this news story about how three-dimensional aerial photos, viewed with
>> special glasses, make it easier to pick out structures on the ground.
>> 
>> <http://www.bbc.co.uk/news/magazine-13359064>
>> 
>> I wonder if any such 3-d imagery is available today?  It would seem to involve
>> having two cameras a set distance apart.  If OSM ever charters a plane again, as
>> was done for Stratford-upon-Avon, England, a few years back, it might be worth
>> taking two cameras instead of one.
> 
> The techniques and the software used in aerial imagery normally
> struggle to reduce the perspective effect to the minimum, so that the
> view is almost isometric.  One of the advantages of that is that you
> can pan around the single image and have the illusion of flying over
> the terrain.  With the perspective effect you couldn't do that, you
> would just have 3D views from a few discrete points like in Google
> StreetView.  You also wouldn't be able to rotate the imagery like you
> can in Nearmap or Bing, because your eyes won't rotate.
> 
> If you want that, though, I don't think you need to resurvey
> Stratford-upon-Avon with two cameras.  With the camera shooting
> continuously you can just pick pairs of consecutive images that are
> some known distance apart and you get the same effect.
> 
> Cheers
> 
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