Reprojecting as NAD83

Topics: SharpMap Project
Jun 26, 2014 at 9:11 PM
Edited Jun 26, 2014 at 9:12 PM
Hi! I have been successfully projecting WGS84 tif files onto OSM tiles using the following code:
var mapBox = new Map(bmp.Size);
var bbox = GeometryTransform.TransformBox(SharpMapUtils.CalculateGeometry(item), SharpMapUtils.Wgs84ToGoogle().MathTransform);
mapBox.ZoomToBox(bbox);

var layer = new GdalRasterLayer(tif_file, tif_file);
layer.ReprojectToCoordinateSystem(ProjectedCoordinateSystem.WebMercator);

etc etc
However I have now encountered a NAD83 TIF file which causes the following exception (on the call to ReprojectToCoordinateSystem):

LOCAL_CS["NAD83 / Maryland (ftUS)",GEOGCS["NAD83",DATUM["unknown",SPHEROID["unretrievable - using WGS84",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]],AUTHORITY["EPSG","2248"],UNIT["US survey foot",0.3048006096012192]] coordinate system is not supported.

How can I modify my code to support this coordinate system in addition to WGS84?

Any help much appreciated - I saw on other threads something about defining a ICoordinateTransformation property but I don't see how that links in with my code implementation... and can't find any examples... :(

Many thanks for any help!
Tim
Coordinator
Jun 27, 2014 at 7:16 AM
I suppose the problem is LOCAL_CS. Where does the coordinate system/tif-file come from, is there a chance that you can get a similar tif file with some PROJCS projection?
Jun 30, 2014 at 4:34 AM
I sent you a private message, but perhaps the contact form isn't working...

I can't get a PROJCS file unfortunately - is it the case that there is insufficient information to be able interpret the GeoRef, or is it just that LOCAL_CS is not supported because there are are too many potential variants to make it practical?

Thanks!
Tim