[Proj] Any access to geodetic functions ??

[Benoît Andrieu]

Thank you so much for your answer, Frank.

So, this leads to some questions (that are somehow related...) :
- how are computed distance calculation between two points by softwares like 
Postgis for example ?
- is the best way to compute distance calculation to use UTM systems ? I 
have to compute distances that could be very long (hundreds of kilometers), 
strong accuracy is not required but I don't want to have more than 1% 
accuracy error.
- in what way are those functions distinct from the proj4 ? Am I wrong to 
use them ? Are there others functions in proj4 that would allow me to do the 
same things that I can do with those functions (distance calculation between 
two points and point positionning given initial point, distance and azimuth) 
?

Thanks again.

Best regards,

Benoît Andrieu
bea at ixsea.com
benoit.andrieu at gmail.com

----- Original Message ----- 
From: "Frank Warmerdam" <warmerdam at pobox.com>
To: "PROJ.4 and general Projections Discussions" <proj at lists.maptools.org>
Sent: Monday, November 10, 2008 10:59 PM
Subject: Re: [Proj] Any access to geodetic functions ??


> Benoît Andrieu wrote:
>> Hi all,
>>  We are using Proj4 in our softwares and we are using too Mapserver 
>> (FWTools compilation).
>> Actually, we are using custom built dlls for Proj4 : proj.dll and 
>> geod.dll. Those builds are based on the Proj4 4.5.0 version.
>> Why we have custom builds is that there was at the time no access to 
>> geodetic functions (and I need them... ^^).
>>  From what I remember, this is the kind of messages that made me make 
>> custom builds :
>> http://osdir.com/ml/gis.proj-4.devel/2006-12/msg00006.html
>>  We are actually switching from FWTools 1.3.2 to FWTools 2.2.6 which 
>> should embed Proj4 4.6.1.
>> So if I want my softwares to be synchronized with this version I would 
>> have to recompile a Proj4 4.6.1 to have access to the geodetic functions 
>> 'except' if they are already exported.
>>  So my question is : are the geodetic functions now exported ? (please 
>> answer yes ...)
>> And if affirmative, in which dlls will I be able to find them ? (coz I 
>> can't find them actually)
>
> Benoît,
>
> Currently the geodesic functions are not exported from proj.dll, nor
> (I think) are they even built into the DLL.   I'm a bit hesitant to treat
> them as part of the support PROJ.4 API since they are quite distinct
> from the core of PROJ.4.  The geod_* functions also depend on global
> variables which is not a pattern I'm keen on setting in stone.
>
> 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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