Using GDAL for reading DTED 2 (and more generally elevation data) is a perfectly valid and common use case.
I'd encourage you reading http://gdal.org/gdal_datamodel.html first and then looking at the API doc. The DTED grid is seen as a standard raster. So if gt is the geotransform returned by GDALGetGeoTransform(), (x,y) the pixel coordinates in the DTED file corresponding to the (longitutde, latitude) you're interested in, you have the following relationship : x = (longitude - gt[0]) / gt[1] y = (latitude - gt[3]) / gt[5] Then using GDALRasterIO(), you should be able to extract a region into a buffer of yours and compute the max elevation. As far as performance are concerned, the column orientation of DTED is generally a bit painful when using scanline oriented algorithms. You might want to bench for your use case if setting the GDAL_DTED_SINGLE_BLOCK environment variable to TRUE might help. See http://gdal.org/frmt_dted.html Best regards Even > Hi, > > > > I'm beginner in development using GDAL. So I'd like some advises and > > tips, let me explain what I need to do. > > > > I need to load a DTED file level 2 and given the parameters > > latitude,longitude and width I must create a region (rectangle) and > > find the highest elevation in the grid points inside this rectangle. I > > need it to be fast, I don't know exaclty how slow GDAL is, so I need > > to understand which strategies to useds to increase de speed of this > > routine. > > > > I didn't find source code examples of DTED loading with GDAL, So there > > are lot's of doubts I have, such as how GDAL stores the DTED since it > > was loaded (in an image file?), how to represent this grid area (a > polygonon area with elevation points), how to get the elevation of a point > > given (lat, lon). > > I'd be glad to receive examples, references and tips about it. > > > > Thanks > > Ricardo _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
