[Proj] GeoTiff <-> Proj.4
support.mn at elisanet.fi
support.mn at elisanet.fi
Sat Oct 4 03:56:08 EDT 2008
"Gerald I. Evenden" <geraldi.evenden at gmail.com> kirjoitti:
> On Friday 03 October 2008 11:25:47 am support.mn at elisanet.fi wrote:
> > Hello,
> >
> > I am still asking if it is totally not possible to use omerc to decode
> > GeoTiff projections 3,4 and 5. The problem seems to be wha to do with the
> ...
> > http://en.wikipedia.org/wiki/American_National_Standards_Institute
>
> I first thought was: "what a good idea," but skimming on to ISO reference the
> criticism section brought up the cost involved and that reminded me of a long
> ago experience. I thought it would be a good idea to get a copy of the ANSI
> C standards but suddenly ran into the $$$ for a copy.
>
If not ANSI, why not CEN?
http://www.cen.eu/cenorm/homepage.htm
"CEN, the European Committee for Standardization, was founded in 1961 by the
national standards bodies in the European Economic Community and EFTA countries."
> > More about Geotiff <-> Proj.4:
> >
> > Ref 1:
> > http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_2sp.
> >html
> >
> > Ref 2:
> > http://www.remotesensing.org/geotiff/spec/geotiff3.html#3.1.3.
> >
> > Ref 1 gives:
> >
> > +proj=lcc
> > +lat_1=Latitude of first standard parallel
> > +lat_2=Latitude of second standard parallel
>
> They should really be called the secant parallels. There is
> nothing "standard" about them.
>
> The alternate lcc is to specify the parallel of tangency and then k_0 which
> does the same thing.
>
> > +lat_0=Latitude of false origin
> > +lon_0=Longitude of false origin
>
> Oh, please! "of false origin" good grief.
>
> > +x_0=False Origin Easting
> > +y_0=False Origin Northing
> >
> > Ref 2 gives:
> >
> > +proj=lcc
> > +lat_1=Latitude of first standard parallel
> > +lat_2=Latitude of second standard parallel
> > +lat_0=Latitude of natural origin (ProjNatOriginLatGeoKey)
> > +lon_0=Longitude of projection center (ProjCenterLongGeoKey)
> > +x_0=False Origin Easting
> > +y_0=False Origin Northing
>
> Terrible, terrible. Proj may have also been guilty of the "standard" part.
>
> > I am starting to belive that best way to deal with the problem is to first
> > allocate lat_1, lat2, lat_ts and then start to look after any lat or lon
> > and put them to lat_0 and lon_0. Since every creator of GeoTiff files puts
> > them randomly somwhere what is left.
>
> lat_ts is not involved with conics.
>
Yes, I was more thinking a general method to connect parameters regardless
of the specific projection.
> Is there an editor or editing group associated with these sites?
I don't know, LibGeoTiff or remotesensing?
Janne.
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