[postgis-users] Area and scale completely wrong

[Nicolas Ribot]

Johan,

SRID 4326 seems good to me to represent GPS points (you should check
your GPS manual to ensure it gives data in the WGS84 Datum).
As Strk said, you will have to project your data into a cartesian
coordinate system in order to compute areas and distances.

Nicolas


On 11/25/05, Johan Wehtje <genwolf at gmail.com> wrote:
> Nicholas,
>  I remain a  little unclear about how I determine which SRID to transform
> to.
>  I have Waypoints downloade from a garmin GPS, and I used WGS84 (SRID 4326)
> to import the waypoints. I Assume the porblem is that I have the data in Lat
> Long Decimal Degrees - But I cannot see a corresponding Geographic SRID for
> WGS 84.
>  ( I am thinking that loading GPS Co-ords into Postgis would have to be good
> Candidate for an FAQ question).
>  Any ideas?
>  Cheers
>  Johan Wehtje
>
>
> On 11/15/05, Johan Wehtje <genwolf at gmail.com> wrote:
> > Thanks Nicolas.
> > I will give that a try
> >
> >
> >
> > On 11/15/05, Nicolas Ribot < nicky666 at gmail.com> wrote:
> > > > Thanks Baren and strk - that was the problem, the file was in decimal
> > > > degrees.
> > > >
> > > >  Can these files be used in Postgis ? is it just a matter of finding
> another
> > > > SRID, or do I have to convert them sowehow?
> > > >
> > >
> > > Hello Johan
> > > You can use these files in Postgis, setting the right SRID for them.
> > > (a geographic system in your case)
> > > You may also transform them to another reference system by knowing the
> > > source and target spatial reference systems SRID. (transform()
> > > function).
> > > Storing them in lat-long won't allow you to compute precise distances,
> areas.
> > > So transforming them to a cartesian reference system is a good option.
> > > Look in the spatial_ref_sys table to find the SRID corresponding to
> > > your projection.
> > >
> > > Nicolas
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> >
> >
>
>
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