##GeoTiff Explorer
Some years ago I wrote a little program to download DEM data from the italian "Portale Cartografico Nazionale" (http://www.pcn.minambiente.it/GN/) available at http://www.trainsimhobby.net/infusions/pro_download_panel/download.php?did=1340
When I wrote it I needed to download data for Ahrntal in South Tirol and the program worked fine. Some weeks ago I downloaded the data for a region near Rimini on the Adriatic sea.
When I used that data in the railways simulator I saw an hight wall where I espected to see the sea 
This tool borns to investigate the problem and to solve it, but can be useful to learn as GeoTiff are built