distorted geometries

Topics: SharpMap v0.9 / v1.x, WinForms Controls
Feb 5, 2009 at 9:28 PM
Hi All,

my initial situation: I have world map data, this is shown in the map view (stretched WGS84/srid 4326) 

I draw a circle (calculated polygon) near the +/-180 degrees line, so on the left or right side in the map view. Then I get a distorted presentment. It reach from one to another side like a hose.

My expectation is: Getting two half circles one left and the other one on right side...What's the trick here? Is it possible anyway?

Thanks in advance, puNk

v 0.9
Feb 6, 2009 at 9:12 AM
Hi puNk, Morten has some good posts relating to this on his website http://www.sharpgis.net/category/Spatial-References.aspx particulary the articles "Why EPSG:4326 is usually the wrong “projection” and "Straight lines on a sphere" hth jd
Feb 6, 2009 at 10:47 PM
Thanks for Your answer!

In my case I have a warehouse with world map sample data. I retrive the data ordinary in wgs84 with the SharpMap.Data.Providers.MsSqlSpatial - provider and  the map view shows the "stretched" map.

So, my layer has no information about the projection (its wgs84 I create the source CS with CoordinateSystemFactory). Now, when I use coordinate transformation for an specified layer, the map receives an envelope near 0 0 0 0. I have tried some samples here in the forum.