Software: ArcGIS
Sources: http://data.geocomm.com/

DEM(Digital elevation model) contains an array of elevation measurements, usually organized as a square or rectangular grid.
The process of creating a DEM in the ArcGIS environment can be divided into three phases:
i) acquisition of the DEM data from a secondary source
ii) converting the DEM into a format ArcGIS can work with
iii) the creation of shadedrelief models, slope and aspect maps and isolines for topographic maps.