[OSM-talk] Coastline errors now updated daily

[Robert (Jamie) Munro]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Martijn van Oosterhout wrote:
> On Nov 21, 2007 1:19 AM, Robert (Jamie) Munro <rjmunro at arjam.net> wrote:
>> Can you add a draggable zoom thing? (like on the informationfreeway.org
>> page) I usually shift drag to zoom in to an area (a fantastic, but
>> fairly hidden openlayers feature), but I have to click the "-" symbol
>> lots of times to get back to where I started.
> 
> Done...

That's great. Can we get one of those on openstreetmap.org as well, by
the way?

>> Can you add a T at H layer to the layer picker? Sometimes it has a
>> different opinion of what the coastline is like, and it would be useful
>> to compare them.
> 
> Done

Thanks - that's really handy.

>> This one may be more complicated: Would it be possible for the algorithm
>> to indicate where coastlines seem to be pointing in the wrong direction,
>> i.e. not having the sea on the right hand side.
> 
> Hmm, if we knew which way the coastline was supposed to go we'd be able
> to fix automatically...
> I'm wondering if maybe I could put arrows on the edges, but I don't
> know how to do that yet. Would that be sufficient?

The problem is that if there is a small island that is correct except
that it goes clockwise instead of anti-clockwise, then AFAICS, it will
be rendered blue on blue, i.e. invisible. I think I have found a couple
because they had incorrect costlines nearby, and I downloaded them together.

If the algorithm could make visible where this has happened somehow,
that would be a great help. Possibly if you made the sea a
semi-transparent dark blue, rather than a light blue, that might do the
trick - water on top of water would show a darker shade. Land on land
may be harder.

If you can work out an algorithm to mark those errors with a coloured
spot, so that you can see it even at low zoom levels, that would be even
better. Once they are visible, they are easy to fix in JOSM, and you can
verify that you are fixing the right thing by comparing with Landsat
imagery.

Robert (Jamie) Munro
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (Darwin)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFHRYm6z+aYVHdncI0RAupIAJ9uKP8fHuKtVlAmWRvz5Z70nRZU7QCeLTiM
ipIoR0QvW26/X5EEt4RaGCI=
=VLaq
-----END PGP SIGNATURE-----