[GRASS-user] EPSG code for KML

[Bulent Arikan]

On Sat, Jul 10, 2010 at 6:33 PM, Hamish <hamish_b at yahoo.com> wrote:

> Bulent wrote:
> > I occasionally use Google Earth –GE– (kml files) and I am aware of the
> > fact that there is a bit of distortion (i.e., metric offset) between GE
> > and other projections for a variety of reasons. I am wondering if anyone
> > knows whether there is an EPSG code for KML format so that I can create
> > a LOCATION in Grass using this code and avoid/minimize such distortions
> > when I import vector files.
>
> It is fundamentally broken, do not use it for serious GIS work. It is
> only valid for visual use and saving cpu cycles on large deployments.
> (which is both acceptable and very important for folks like google)
>
> (epsg initially refused to include it but finally caved to mass user
> pressure)
>
> but if you do want to use it, it's just the mercator projection with
> a spherical ellipsoid using the WGS84's ellipsoid's major Earth radius
> as the only sphere radius. quite simple to define.
>
>
> Hamish
> -----------
>

I was wondering about this. I read several online articles about the
problems and the doubts that EPSG has. Unfortunately, I was planning to use
this for my archaeological work, which requires accuracy such as locating
the trenches and the features, like walls. My issue is, when I need to show
polygons (e.g., a rectangle representing a trench), I transfer my GPS points
(the readings at 4 corners) to GE and create a polygon there, save it as
KML. Then, I open this in QGIS, make a shape file there and import it into
GRASS. I suspect there is some distortion and this is a far too complicated
routine but I do not know a more practical way.

' v.in.gpsbabel ' works fine for retrieving points and tracks from my
device. Alternatively, I may digitize the points to create polygons after
they are imported in GRASS. I still have to try ' v.in.ascii '


-- 
BÜLENT
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