[Proj] Expanding a proj4 CRS definition

Andre Joost andre+joost at nurfuerspam.de
Tue Mar 4 12:50:06 EST 2014

Hi Phil,

Am 04.03.2014 15:41, schrieb Phil Elson:
> I'm curious to know whether it is possible for proj4 to return a complete
> representation of a projection definition. For instance, supposing I gave a
> proj4 string of:
> +proj=merc
> It would be useful to get back a projection definition such as:
> +proj=merc +lat_ts=0 ...

gdalsrsinfo does exactly that.

> Similarly, though this is less important to me, is it possible to go from:
> +init=epsg:3309
> To
> +proj=aea +lat_1=34 +lat_2=40.5 ...
> Without just returning the string found in share/proj/epsg?

What else should it return? That is the proj string behind the EPSG code.

> I guess what I'm really asking whether there is an internal representation
> of these values which can then be used to pump out a string suitable for
> passing through to proj4 later on?

I guess you are looking for default values which you don't want to add 

You can play with gdalsrsinfo and look what it returns on incomplete input.

André Joost

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