[mapguide-dev] area calculation conversion to meters

[Paul Spencer]

Thanks everyone.  I've got it working now.  For the record, I tried  
all the auto projections and only 42004 gave horrible results for my  
test case.

There was no perceptible difference on small features between the  
other three projections.

Cheers

Paul

On 4-Dec-06, at 11:18 AM, Daniel Morissette wrote:

> Paul Spencer wrote:
>> Sweet, thanks Daniel.  Can you confirm something for me please?   
>> In the sprintf, there is a zoneStr variable that appears to have  
>> no value and perhaps shouldn't be there?  As far as I can see,  
>> there are only two substitution points in the string and zoneStr  
>> shouldn't go in either one :)
>
> I think you're right, you should probably ignore zoneStr.
>
> BTW, here is the same definition in PROJ.4 format, from MapServer's  
> implementation of the WMS AUTO projections (function  
> _msProcessAutoProjection() in mapfile.c):
>
>
>       case 42001: /** WGS 84 / Auto UTM **/
>         nZone = (int) floor( (dLon0 + 180.0) / 6.0 ) + 1;
>         sprintf( szProjBuf,
>                  "+proj=tmerc+lat_0=0+lon_0=%.16g+k=0.999600 
> +x_0=500000"
>                  "+y_0=%.16g+ellps=WGS84+datum=WGS84+units=%s",
>                  -183.0 + nZone * 6.0,
>                  (dLat0 >= 0.0) ? 0.0 : 10000000.0,
>                  pszUnits);
>
> Daniel
> -- 
> Daniel Morissette
> http://www.mapgears.com/
>
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+-----------------------------------------------------------------+
|Paul Spencer                          pspencer at dmsolutions.ca    |
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|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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