Odd Vector behaviour using Lambert Azimuthal Equal Area and Global Vector [Additional Information]

pw p.willis at TELUS.NET
Fri Apr 27 16:24:41 PDT 2007


pw wrote:
> Hello,
> 
> I am working with mapserver version 4.10.1.
> 
> I am using a global polygon vector of land in SHP format.
> The vector has a latlong coordinate system. The vector
> has land color filled and water blank.
> 
> The map file that mapserver is using defines a map
> with a Lambert Azimuthal Equal Area projection (laea).
> 
> Mapserver has no problem with the map Lambert projection
> centered over most global coordinates.
> 
> PROBLEM:
> 
> I am finding that mapserver maps the land vector
> inverted with land blank and water color filled when
> I cross various geographic boundaries with my Lambert projection.
> 
> I have posted a map showing where Mapserver inverts the
> opaque and transparent colors of the polygon vector
> when using Lambert AEA.
> 
> http://www3.telus.net/amphora/images/index.html
> 
> QUESTIONS:
> 
> Is this a problem with Mapserver, GDAL, Proj4,...???
> Has anyone encountered this before?
> Is the problem workable or do I need another global
> land vector centered on the other side of the globe?
> 
> Thanks for any info,
> 
> Peter
> 
> 

The problem is also related to map scale.
I have provided samples images at:

http://www3.telus.net/amphora/images/index.html

Peter



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