[OSM-talk] Fwd: Possible method to survey countryside features

[Robert (Jamie) Munro]

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Torsten Breda wrote:
> 
> 
> ---------- Forwarded message ----------
> From: *Torsten Breda* <torstiko at gmail.com <mailto:torstiko at gmail.com>>
> Date: 07.05.2007 02:33
> Subject: Re: [OSM-talk] Possible method to survey countryside features
> To: "Robert (Jamie) Munro" <rjmunro at arjam.net <mailto:rjmunro at arjam.net>>
> 
> Or just use a compass at both positions!

Yes, but then you have to decide everything you want to map in advance.
You might spend ages noting down the directions from the first place of
things you can't see from the second place. If you have 2 photos it's
easy to go back and find things you didn't realise you could see from
both later. If you add a third photo later, you don't have to revisit
the first two sites to find things visible from the third site, you just
get out the photos. If you have something like a power line, you may not
be able to usefully note down which pylon is which, but from the photo
you can probably work which pylons are the same and double check based
on tiny differences like the way the insulators are hanging, or where
the sign that says danger do not climb is fixed. You couldn't
realistically note down that stuff if you were using a compass.

It's probably more accurate than an average compass, due to compasses
being affected by stray magnetic fields, magnetic north not being north,
and average compasses just not being high precision instruments. It's
true that if you happen to have high quality compass binoculars you will
get a better angle, but most people don't. Most OSM people do have a
digital camera, and a GPS that they use for normal street mapping
anyway, so they need no extra equipment (not even a compass) to try this
new form of mapping.

I forgot to put the link to autostitch.
http://cs.ubc.ca/~mbrown/autostitch/autostitch.html
(download the demo version) It's much easier to use than you might
imagine. Just take the photos, run autostitch on the folder, and you get
a panoramic photo out with the left and right edges meeting. It turns
rectilinear images from your camera into images where pixels are equal
angled, and it auto adjusts for any camera.

Robert (Jamie) Munro

Ps. Does anyone happen to have 2 georeferenced panoramic photos that can
see the sites from which each other were taken handy? Actually, looking
at http://flickr.com/map/ and searching for autostitch seems to be a way
to find them.
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