[OSM-talk] Coastlines

[Nick Black]

On 8/16/06, Steve Chilton <S.L.Chilton at mdx.ac.uk> wrote:
> Tool someone (sory forget who) developed that was mentioned in talk-list
> and is detailed at:
> http://wiki.openstreetmap.org/index.php/FAQ
> Actual link is:
> http://www.geoskating.com/gmap/osm-gmap.html
> I am aware of the dangers of using anything to do with Google (which was
> discussed on list at length) but find this a really useful tool for
> planning and checking purposes - and I repeat NOT for using or
> extracting any data.

Certainly. I think we are within the boundaries of legal use on this
one.  I need to reference it for some university work, that's why I
need the source. Damn academic integrity.........

>
> Cheers
> STEVE
>
> Steve Chilton, Learning Support Fellow
> Learning and Technical Support Unit Manager
> School of Health and Social Sciences
> Middlesex University
> phone/fax: 020 8411 5355
> email: steve8 at mdx.ac.uk
>
> Chair of the Society of Cartographers:
> http://www.soc.org.uk/
> 2006 SoC Summer School at Keele Uni:
> http://www.esci.keele.ac.uk/soc/
>
>
> -----Original Message-----
> From: Nick Black [mailto:nickblack1 at gmail.com]
> Sent: Wednesday, August 16, 2006 5:00 PM
> To: Steve Chilton
> Cc: talk at openstreetmap.org
> Subject: Re: [OSM-talk] Coastlines
>
>
> On 8/16/06, Steve Chilton <S.L.Chilton at mdx.ac.uk> wrote:
> > Further investigation leads me to think there might be some mismatch
> > problems with this coastline data. If you zoom in in OSM and compare
> > the alignment to the satelite image it appears to be misaligned.
> > Following screenshot suggests that it is off slightly in a southerly
> > direction. If you look at the truncated yellow roads they seem to
> align
> > well with underlying image. One would really need higher-res satelite
> > imagery to reach a more scientific conclusion.
> > http://wiki.openstreetmap.org/index.php/Image:Iomoversat.png
> > It is even more evident if you overlay the data over Google map, where
> > it appears to be all shifted to south-east.
> > http://wiki.openstreetmap.org/index.php/Image:Iomovergoogle.png
>
> What was the source of this image? (The OSM data overlaid onto Google
> maps)
>
> nick
>
> > What is missing is any inland detail to verify against. This does in
> > fact point up the poor quality of this particular Google map data. See
>
> > for example how the map shows the large offshore island as being part
> > of the mainland, encompassing the smaller island on the way!
> >
> > What I suggest would be useful would be to convert the dataset for the
>
> > Isle of White, incorporate within OSM, and allow cross checking there
> > against GPS data, OSM satelite data and Google map data. Is that
> > posible? What does anyone think? I still think this might be a useful
> > dataset, but we need to know what we are getting if we accept it on a
> > larger scale as a coastline dataset.
> >
> > Cheers
> > STEVE
> >
> > Steve Chilton, Learning Support Fellow
> > Learning and Technical Support Unit Manager
> > School of Health and Social Sciences
> > Middlesex University
> > phone/fax: 020 8411 5355
> > email: steve8 at mdx.ac.uk
> >
> > Chair of the Society of Cartographers:
> > http://www.soc.org.uk/
> > 2006 SoC Summer School at Keele Uni: http://www.esci.keele.ac.uk/soc/
> >
> >
> > -----Original Message-----
> > From: dankarran at gmail.com [mailto:dankarran at gmail.com] On Behalf Of
> Dan
> > Karran
> > Sent: Tuesday, August 15, 2006 6:41 PM
> > To: Steve Chilton
> > Cc: talk at openstreetmap.org
> > Subject: Re: [OSM-talk] Coastlines
> >
> >
> > On 8/15/06, Steve Chilton <S.L.Chilton at mdx.ac.uk> wrote:
> > > Data quality looks quite reasonable on this sample. I have made SVG
> > > (saved as PNG) of the mainland bit of the example below.
> > > See:
> > >
> http://wiki.openstreetmap.org/index.php/WikiProject_Isle_of_Man#Assist
> > > an
> > > ce
> >
> > Moved to
> >
> http://wiki.openstreetmap.org/index.php/WikiProject_Isle_of_Man#Coastlin
> > e
> >
> > > There are two roads that go in the sea (1 in Port Erin and 1 in Port
> > > St
> > > Mary) but local gps work and editing could cure that. On balance I
> > would
> > > say "better in than out" (ie if upload has worked for whole of
> island
> > > then repeat in stages for other areas). Is projection an issue over
> > > larger areas?
> >
> > The road in Port Erin is based not on GPS tracks but on the Landsat,
> and
> > the one in Port St Mary is the harbour I think. There are a couple of
> > other close calls from real GPS data, but they coastline around those
> > areas is easily fixed.
> >
> > > NB: renderer (osmarender2) doesn't recognise all of linework as some
> > > is still in class= rather than highway= format. Maybe worthwhile to
> > > also check in a more (data) populated area. Has Douglas been mapped
> in
> >
> > > detail? Maybe I'll have a look at that when I have time.
> >
> > There are some bits around Douglas, but not as much as Port Erin/Port
> St
> > Mary yet. I should go through and recategorise PSM as Rob put a lot of
> > work into that and it'd be a shame for it not to show up when
> rendered.
> >
> >
> > Cheers,
> > Dan
> >
> > --
> > Dan Karran
> > dan at karran.net
> > www.dankarran.com
> >
> > _______________________________________________
> > talk mailing list
> > talk at openstreetmap.org
> > http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
> >
>