[Proj] minor proj bugs

Frank Warmerdam warmerdam at pobox.com
Wed Jul 28 19:31:46 EDT 2004

Britton Kerin wrote:
> Hello,
> Not sure this list is alive (the archive link on the web page doesn't 
> work).  The web interface to bugzilla isn't working either though, so here 
> goes:


Have have removed the old archive link and noted that the subscribe/unsub
link also leads to archives.

> 1. There is a discrepency between the pj_geocentric_to_geodetic 
>    and pj_geodetic_to_geocentric prototypes in proj_api.h and the 
>    corresponding definitions in pj_transform.c.  The second argument in 
>    the signatures in the definitions is 'es', which I assume stands for 
>    eccentricity squared.  The first thing the functions do is compute 'b'
>    (I assuem the minor axis treating es as eccentricity squared, so I 
>    guess eccentricity squared s what it is.  The prototypes in proj_api.h
>    have a second argument called 'ra' however, which is confusing.  It
>    looks to me like the names in proj_api.h should be changed from 'ra' to
>    'es'.

Agreed.  I have fixed this in CVS.

> 2. The description of the -format option in the cs2cs man page contains an 
>    unecesary sentence:
>               Format is a printf format string to  con-
>               trol  the form of the output values.  For
>               inverse projections, the output  will  be
>               in  degrees when this option is employed.
>               If a format is specified for inverse pro-
>               jection  the output data will be in deci-
>               mal  degrees.   The  default  format   is
>               "%.2f" for forward projection and DMS for
>               inverse.

Fixed in CVS.

> 3. Advertise the new general transformation capabilities (cs2cs and 
>    corresponding capabilities of 'projPJ' type in library) better!  They 
>    are really cool and I almost missed them entirely.

Advertise where?  I can't update the postscript/pdf manuals as they are "readonly"
at this point.  But the new stuff is listed in the pj_init man page and cs2cs
has a SEE ALSO'ed man page.

> 4. Some of the API routines look redundant with each other now.  For 
>    example, if I understand correctly: pj_datum_transform is now subsumed 
>    into pj_transform?  And pj_fwd and pj_inv are also simple versions of 
>    pj_transform?  This redundance should probably be discussed somewhere 
>    to prevent confusion.  Or, if they are different, the differences 
>    should be described.

pj_transform() is built by using the various component transformations.  The
pj_datum_transform() isn't really intended to be too public, and I don't
think I have documented it anywhere.

> proj is excellent in general though, definately worth keeping it up to 
> speed and polishing up the docs.


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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