[Proj] Expanding a proj4 CRS definition

[Andre Joost]

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 
explicitly.

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

Greetings,
André Joost