[GRASS-dev] proj -l
paul-grass at stjohnspoint.co.uk
Sun Oct 8 11:20:28 EDT 2006
On Sun, 8 Oct 2006, Hamish wrote:
> I just learned of the "proj -l" command from PROJ.4. (post on Proj.4 ml)
> Maybe it would be useful in a future auto-gen g.setproj GUI wizard [if
> GRASS moves to "full" use of proj.4].
There was some discussion about this on the PROJ list a while ago when
someone was trying to tidy up inconsistencies in the proj -lP with a view
to automatically parsing it for exactly such a purpose:
but it became apparent that the output isn't reliable enough. Gerald
Evenden's usage paradigm seems to always have been that before formulating
a set of PROJ parameters the user needs to read the full documentation for
that particular projection and understand exactly which parameters they
need. This manifests itself in some interesting ways such as the multiple
ways to represent an lcc (Lambert Conformal Conic) projection. I'm sure
there are others but I have to confess I don't really know very much about
this, apart from the fact that the intention of the -lP output is
inconsistent with it being automatically parsed. But it may be possible!
As I said before it would be great to make this functionality part of the
re-worked PROJ.4 library that Frank is proposing to do at some point.
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