[MetaCRS] [Proj4js] geocent proj issue.

[Mike Adair]

  Hi Clement,

The contents of the old geocent.js file is now contained in the main 
proj4js.js file and it mainly handled conversions to/from 
geocentric/geodetic coordinates.

I assume you are trying to convert from geocentric to Lat/long coords?  
I see that PROJ.4 handles that case where the geocent 'projection' is 
defined with the identity transform (like you have done) but i don't 
think that will work in Proj4js.  You may be able to step through a 
transformation and see where the geocentric - geodetic transform occurs 
and where any errors may be introduced.

Mike



On 9/8/2010 6:54 AM, Clément Ronzon wrote:
> Hi everyone!
>
> I'm new on this mailing list, so I'll introduce myself in a few words: 
> my name is Clément Ronzon, I'm living in France but I'm going to move 
> to Mexico in a few months, I'm working in Informatics design and 
> development for France Telecom, and I'm the developer of TWCC 
> (http://twcc.free.fr).
>
> I have a question about geocent projections.
> I have the following definition :
> /Proj4js.defs["IGNF:AMST63"] = "+title=Ile d'Amsterdam 1963 
> +proj=*geocent* +towgs84=109.7530,-528.1330,-362.2440 +a=6378388.0000 
> +rf=297.0000000000000 +units=m +no_defs";/
>
> But when proj4js tries to load the geocent proj file it fails because 
> there is no geocent.js file. Actually I found that this file has been 
> removed (http://trac.osgeo.org/proj4js/ticket/16).
>
> So I tried to create /lib/projCode/geocent.js with this content:
> /Proj4js.Proj.geocent = {
>     GEOCENT_LAT_ERROR:0x0001,
>   init: function() {
>     //no-op
>   },
>   forward: function(pt) {
>     //identity transform
>     return pt;
>   },
>   inverse: function(pt) {
>     //identity transform
>     return pt;
>   }
> };/
>
> But it seems that the result of transformations is wrong (some meters 
> on X and Y).
> Could someone tell me how can I solve this issue please ?
>
> Thanks in advance! And, by the way, congratulations for those metaCRS 
> projects!!!
> Clément Ronzon
> 151 Av. Félix Faure
> 69003 LYON, FRANCE
> Tel. # : +33 (0)9 54 43 12 20
> Fax # : +33 (0)9 59 43 12 20
> Cell. # : +33 (0)6 08 21 23 27
> http://twcc.free.fr
> http://www.grottocenter.org
> http://www.zakbag.com
>
>
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-- 
    Michael Adair
    Senior Software Architect
    DM Solutions Group Inc.

    Office: (613) 565-5056 x26
    madair at dmsolutions.ca
    http://www.dmsolutions.ca
    http://research.dmsolutions.ca


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