[Proj] GeoTiff <-> Proj.4

support.mn at elisanet.fi support.mn at elisanet.fi
Thu Oct 2 09:14:13 EDT 2008

Frank Warmerdam <warmerdam at pobox.com> kirjoitti:
> The page at:
>   http://geotiff.maptools.org/proj_list/
> represents a "best effort" attempt to document the
> correlation between geotiff definitions and proj.4
> (as well as EPSG and OGC WKT).

Yes, I have been reading that. There seem to be several
problematic projecions. "Omerc" number 3, 4 and 5 in
GeoTiff does not import to Proj4 at all, or does it?

Geotiff number 6, "merc" is not used at all? Or should not
be used?

Geotiff number 15, "stere" uses "lat_0=CenterLat", not
mentioned? Or is it only intergraph?

Geotiff number 27, "tmerc" soth oriented can not be used
directly, unless you turn all signs somewhere using extra
 "ifs"? Isn't that forbidden, to have a south orientated map?
How the people know where the north is if that is upside

And Intergraph is using mostly different fields instead of
those given in your link?


Linear names are easy: whatever given ->x_0 and y_0

Ratio names also easy: whatever given -> k_0

Angular names are most difficult and all are not using same
names? There is no general rule? Ok. I make a mapping
table for the names then.


BTW: There is couble of typos. Lcc(1) and Lcc(2) are entered
both as number 9. I am assuming that Lcc(2) is number 8 and
Lcc(1) is number 9?

Regards: Janne.

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