DEM - aeheathc/LaharPlot GitHub Wiki
DEM (Digital Elevation Map) files are a 2d matrix of floating point numbers that describe the topography of a region. Sometimes they use other data types, but we deal with them all as float anyway because of the limits of our geospatial data input library.
Geocomm.com has all the DEM files we will be using. You can download it for free there. They also have other types of data that cost money, but the DEMs are free.
SDTS (Spatial Data Transfer Standard) is the format for DEM files used by the USGS. It is said to be complex and difficult to work with; fortunately, we have GDAL to do the hard part for us. GDAL is a open source (permissive free software license) library that provides a common interface for reading many geospatial data files in C++.
Our file codec library GDAL allows the reading and writing of a slew of formats not limited to SDTS. This even includes many formats that are not actually called "DEM" files, such as GeoTIFF. Since we get a common interface to all of them, we don't really care what the underlying format is and can keep calling them all DEMs.