GDAL / Projections

Topics: Algorithms, SharpMap v0.9 / v1.x
Dec 18, 2007 at 10:24 PM
I am using the GdalRasterLayer to load various raster files into sharp map. This has been working well, until I decided to expand the files to include GeoTiff and Jpeg2000 files which were in a different coordinate system. I thought that SharpMap would normalize everything into a common coordinate system. As this does not seem to be the case, I was hopeful someone might have an idea of how to force all the loaded Raster files, or any file into a specific coordinate system?
Dec 19, 2007 at 1:36 AM
I'm not aware that you can do this dynamically. GDAL has tools to reproject and convert imagery... or at least there are FW Tools that sit on top of GDAL to do this. Reprojecting an image is an intense task. When we need to reproject county-wide SID imager to an ajoining UTM zone, it often takes an hour. Clearly, something where you want to save the reprojected imagery one time, and then access that version in the future. SharpMap and ProjNet do a nice job of dynamic reprojection of vector data.
Dec 19, 2007 at 1:45 PM
I have added automatic on the fly reprojection and rotation to the GdalRasterLayer. I am planning on submitting the code for this back sometime soon.
Dec 19, 2007 at 2:11 PM
Oh, wow!!!! I really look forward to exercising this. Do you reproject the view that is being displayed, or the entire image? For instance, on these 400mb sid images, we are only looking at a couple square miles of a 600 square mile image at a time... do you reproject that extraction from the SID, dynamically, or try to reproject the entire image?
Dec 19, 2007 at 3:13 PM
That's great! Perhaps I can help?
Dec 20, 2007 at 6:52 PM
Check it: http://www.codeplex.com/SharpMap/Thread/View.aspx?ThreadId=19480