[Mapserver-users] documentation bug (was Re: projecting a point in PHP MapScript)

[Chris Black]

D'oh!  I need to put a sticky note on my monitor that says "LONGITUDE is 
X"!  This has bitten me before -- we say 'x, y' but 'lat, long', and 
that always makes me think that latitude is x.  It's working with 
Frank's corrections.  Thank you!

-- Chris

Frank Warmerdam wrote:

> Chris Black wrote:
>
>> Ok, I've stepped up to 3.7, which I downloaded as 
>> mapserver-3.7-win32-php4.3.0-gd2.zip from 
>> http://www2.dmsolutions.ca/mapserver/dl/ (since I'm on Windows, I'm 
>> trying to avoid doing any compilation myself).
>>
>> The behavior has changed somewhat; I now get an explicit failed 
>> return code and an error message.  I'm still not succeeding.  Is 
>> there any way to get a more explicit error message about why the 
>> projection is failing?  Is there a different 3.7 binary and libraries 
>> I should try?
>
>
>
> Chris,
>
> Generally speaking it is hard to get meaningful error messages from 
> PROJ.4
> explaining failure, but a good start is to do testing with the "cs2cs"
> commandline program distributed with PROJ.4.
>
> cs2cs +proj=latlong +ellps=clrk66 +to +proj=utm +zone=10 +datum=NAD27 \
>   +ellps=clrk66 +units=m +no_defs +north
> 38.2052770 -122.37277700
> *       * 0.000
>
> Well, this fails because you have X and Y backwards.  I assume you 
> want to
> translate the location 122.372777E, 38.2052770N? Even though the 
> coordinate
> system is called latlong (longlat also works) the order is 
> latitude,longitude.
>
> Second, you provide a datum definition for one coordinate system but not
> the other.  This seems to cause a problem.  If I change to just listing
> the ellipses things seem OK:
>
> cs2cs +proj=latlong +ellps=clrk66 +to +proj=utm +zone=10 +ellps=clrk66 
> +units=m +no_defs +north
> -122.372777 38.2052770
> 554916.29       4228571.08 0.000
>
> So, try correcting these problems in your script.
>
> Best regards,
>