[mapserver-users] cutom EPSG db for Canada problem

[Frank Warmerdam]

Chuanyun Fei wrote:
> Hi All,
> 
> We current add some epsg codes (got from DM Solutions) for Canada and
> North American into the epsg db located in c:\proj\epsg and
> C:\proj\nad\epsg, for example:
> 
> # WGS84 / Ortho NorthAm
> <42201> +proj=ortho +lat_0=45.0 +long_0=-100.0 +x_0=0.0 +y_0=0.0
> +ellps=WGS84 +datum=WGS84 +units=m no_defs <>
> 
> Our MapScript and MapServer are 3.6 runing on Win2000. We wondering why
> some points work, some don't. For example:
> 
> convert EPSG:4326 => EPSG:42201:
> input (-128, 32)  => (4262324.1145246,4744679.5950324)
> input (-128, 31)  => nothing
> 
> Is there some restraints for the input points (bounding box)?
> 
> Thanks a lot in advance.


Chuanyun Fei,

I believe the problem you are encountering is that the +long_0=-100 flag is
being ignored because there is no such flag.  Use +lon_0=-100.  Without this
change you are 100 degrees further away from the region of validity for this
projection than you think causing a numeric problems.

This is also hinted at by the very large X values (nearly 5 million meters)
you are getting.

It seems that the DM Solutions special coordinate systems need a fix.

Best regards,

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