[Shapelib] using latitude and longitude as coordinates

Ken S. Elvehjem elvehjem at runestone.net
Thu Sep 2 07:49:20 PDT 2004


I have used a couple of tools that are descended from the ShapeLib -- namely ShapeIO, and binaries that were compiled from the Shapelib example c code.

I use unprojected latitude and longitude almost exclusively, and when I have made shape files in the past, they come out looking "proportional".

That is to say that if I outline a rectangle that is twice as long from north to south as from east to west, it will look just like that in ArcExplorer.

I have  recently acquired a 3rd party tool for creating shapefiles.  The shapefiles are correct, faithfully recording the coordinate list for a polygon.  But when I go to look at the polygon w/ ArcExplorer, the polygon is "stretched" in the east/west direction.  

I can see that this happens because ArcExplorer doesn't take the latitude into account for proportioning the picture, but why did it quit? 

I have never had to specify that I was using Polar coordinates before -- and while the points have the right coordinates, the wide picture is disconcerting to my clients.

Any Good Clues???

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