[Openstreetmap] Areal photos for free?

Matt Amos matt at matt-amos.uklinux.net
Sat Feb 19 23:42:20 GMT 2005

On Saturday 19 February 2005 09:53, Amaury Jacquot wrote:
> Petter Reinholdtsen wrote:
> > We can get aerial photos for free by contacting friendly small
> > plane pilot, and get them to bring photo equipment on their
> > trips.
> >
> > What should the equipment look like?
> >
> >  - gps
> >  - camera (still/video?)

high quality still, with a decent telephoto lense, i would have 

> >  - laptop for storage
> >  - correct clock (why?)

??? use the gps for that!

> >  - the shape need to be aerodynamic

only the external parts, i.e: the gps antenna and the camera. the gps 
isnt a problem - we can use a sapphire-type "mouse" which is 
reasonably aerodynamic. the camera would need a decent glass fibre 

> >  - simple mounting and dismounting on wing or wheel (norsk: stag)
> >  - barometric height
> >  - what resolution do we need for the camera

i think it'd need to be pretty good, if we're to resolve 10m wide 
roads at 1000m, or about .3 degrees of arc...

> imho, you'd also need an inertial sensor, so that you can identify
> the attitude of the plane, which would make calculating the
> direction the photo was taken much easier

you'd need a proper 6-dof accelerometer and theyre pretty expensive. a 
cheaper option might be a digital barometer and compass which'll be 
accurate enough over most of the world.

> GPS altitude is not that bad. error is about 4-10 meters or so,
> which is irrelevant when you are at 500 - 1000 meters from the
> ground (about 1%)

actually its more like 30-60m, but at least you'd get a good clean 
signal at 3000ft ;-)

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