[OSM-talk] Coastlines

[Erik Johansson]

On 8/16/06, Nick Black <nickblack1 at gmail.com> wrote:
> 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
>
> Could this be a discrepency due to the definition of the tideline?  If
> the landsat image was taken at high tide, but the shoreline data is
> based on an average tide....

The PGS  data is based on a Landsat image and it's not avaraged. But
that error is very small, considering what you can get. I recommend
"EVS Islands"[1] if you want to know more about shorelines, and
islands.

[1]http://evs-islands.blogspot.com/