[OSRS-PROJ] PROJ tasks and routines

Frank Warmerdam warmerdam at pobox.com
Fri Mar 7 10:52:03 EST 2003

Duncan Agnew wrote:
> What has happened instead is the cs2cs has combined both (B) and (C); certainly
> having both is valuable, and I appreciate that what has been done is done,
> but I would urge that whatever is done to cs2cs to allow it specifically
> to perform the combined (B) and (C), not be added to proj, which is thus
> left simpler for the people who just want to do (A). Mission creep can be
> insidious.


My view has been to reserve the commandline program "proj", and the pj_fwd()
and pj_inv() functions for the task of doing "projections".

The cs2cs and pj_transform() function are conceived of as more general
"coordinate system to coordinate system" converters including datum shifts
and potentially more esoteric stuff.

Within the API there is some "mess" in that the PJ structure, and pj_init()
are used for both sets of functionality.  The PJ structure carries around
a bunch of stuff that is related to datums even when only the projections
capabilities are being used.

In my ideal world the source code of the PROJ tree would be segregated in
such a way that Gerald could work off the same source tree as me, but releasing
a pure PROJ.4 from the traditional subset of code related to projection without
all the datum, and "geod" cruft that goes beyond it.  I would add all the
datum code, and other cruft to produce a "CS-PROJ" (CoordinateSystems-PROJ)
release corresponding to me current PROJ releases.  I do still believe that
many applications and end users want to view things at the coordinate systems
level and that a unified api for that is valuable.

In any event, I would like to stress that I am very pleased to have Gerald
back writing projections code and I hope we can work out a close cooperative
agreement.  Not to fret folks, life is good.

Best regards,

I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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