[OSRS-PROJ] Problem with projecting 180,90 using Mercator

[Gerald I. Evenden]

One VERY simple part of the problem: Mercator projection will not
project data at the Poles---latitude +-90 degrees.

The results are at an infinite distance from the equator.  Sorry.

If you need full global coverage select something like Miller or
for less distortion one of the pseudocylindricals.  Or if you
insist on Mercator reduce the latitude range to +-85 degrees.

On Tue, 2003-07-01 at 19:37, Benjamin Wragg wrote:
> Hi list,
> 
> I'm currently using PostGIS (which uses the proj4 library) to convert
> and store some spatial data. I receive 4 coordinates in lat/long which
> define the extents of a hardcopy map. I use these coordinates to create
> a PostGIS feature. The next step I need to do is convert the feature to
> the desired coordinate system. This works great for most features but
> I've found that if a hardcopy map has been specified with coordinates
> like -180,-90,180,90 (a typical map of the world) the transformation
> crashes. I've questioned the PostGIS list and Paul Ramsey suggested
> running cs2cs manually which is what PostGIS essentially uses for
> transformations. When I run the following:
> 
> 	cs2cs +proj=latlong +ellps=WGS84 +to +proj=merc +lon_0=150.0
> 	180 90
> 
> I get:
> 
> 	* * 0.00
> 
> If I pass in any other coordinate I get values back OK.
> So why is -180,-90,180,90 not being projected? Any suggestions?
> 
> Thanks,
> 
> Benjamin Wragg
> 
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-- 
Gerald I. Evenden <gerald.evenden at verizon.net>

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