Hey Paul/Rory/Bartosz, The building detail and general geometry is pretty awesome and not something that can be achieved from the best Yahoo orthophotos available in Ireland.
Paul, GPS traces are usefull for general road alignment, and the average from a number of traces gives a good indication of the road position. The misalignment between multiple traces for a single road are evidence of the inherent inaccuracy of consumer GPS devices. These devices are definitely not capable of returing this level of detail. Multipathing is another reason that GPS devices fall over when trying to map buildings/structures. Rory, you are correct, roof access would be a creative solution, but highly unlikely. Put any GPS near a building and it's accuracy suffers badly. In fact, if you have ever seen Ordnance Surveys vector mapping products and the building outlines, I'm certain most of it is derived from high resolution orthophotos. Most of my additions to OSM have been thru "Heads-up" digitising off orthorectified Yahoo images, so I have a fairly good idea of what is reasonably achivable! Just having a look through some of Letterkennys comments with the uploads, it seems road data from Tobins (Consulting Engineers) has been used? From my experience all Consulting Engineers drawings have some copyright which would preclude them from use in OSM. Even taken in charge drawings submitted to County Councils have copyright disclaimers. He may well have received suitable 3rd party permissions, BUT, this should be clearly documented on the Ireland Wiki. This would avoid these kinds of emails and the unfortunate and uncomfortable discussions which follow! Cheers Rory keep us posted. Regards, Paul On 1 August 2010 20:21, Rory McCann <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 01/08/10 20:11, Paul O'Shea wrote: >> Paul, is there a particular reason why the Letterkenny map appears to >> you to be from imagery? I'm not challenging your interpretation, I'd >> just like to understand the reasoning for future reference in my own >> mapping. > > Building outlines are hard to get from GPS traces (unless you have free > roam on the roof), but easy to get from aerial imagery. Letterkenny > General Hospital has a detailed building outline: > http://www.openstreetmap.org/?lat=54.95958&lon=-7.73327&zoom=17&layers=M > > > Rory > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.10 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iEYEARECAAYFAkxVySQACgkQABn8MFNz+2GSpgCeORHzIEPs1wYafcsdDTpWGFJt > 4okAn1yC4H+9C7q3l04VwmgNHPEx6eQ5 > =sz51 > -----END PGP SIGNATURE----- > > _______________________________________________ > Talk-ie mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/talk-ie > > _______________________________________________ Talk-ie mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-ie
