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Plot a point using lat/long

Topics: SharpMap v0.9 / v1.x
Jul 29, 2008 at 7:18 PM

I recognize that this topic or similar ones has been brought up before but either the entries weren't answered or the information wasn't enough to get me the solution that I need. I've started with one of the sample apps and rendered a map of the counties in the state of Ohio. I got the shapefile from Now I need to plot points representing zip codes onto the map. I tried creating a transformation between WGS84 and the coordinate system of the shapefile but that didn't produce anything; literally, I got a blank image.

I could really use some help to move forward. I suspect that I'm missing something simple.



Also, I'm missing something with my mental image of how SharpMap works. My datasource, the shapefile, has a coordinate system but the layer does not have a transform. The CoordinateTransformation property is NULL. What is going on? Is the coordinate system of the map the same as the data source since there is only one layer? What happens when you add another layer? Do you have to transform the coordinate system of the second layer to the first? Can anyone provide some clarifications?
Aug 7, 2008 at 12:07 PM
Hi Mike, the coordinate transform is not added automatically, you need to apply it youself. See ProjNet (CoordinateSystemFactory and CoordinateTransformationFactory) and a recent post by artemon. hth jd