The Alberta Provincial Terrain is a component of the Alberta Provincial Digital Elevation Model. The Alberta Provincial Digital Elevation Model has five components: the Alberta Provincial Terrain, the Alberta Provincial 25 Metre Raster, the Alberta Provincial 100 Metre Raster, the Alberta Provincial 25 Metre Hillshade and the Alberta Provincial 100 Metre Hillshade. The source data is contained within the feature dataset that houses the Alberta Provincial Terrain. The source data consists of feature classes generated from the mass points, soft breaklines and hard breaklines that were stored as ASCII generate files in 1:20 000 scale National Topographic System (NTS) blocks. The source data has three origins: Digital Elevation Model: Alberta 1980 1995 60K, Southwestern Alberta 1979 1996 50K and Northeastern Alberta 1955 1986 50K. These three datasets were processed separately and tiled seamlessly along their borders. The Digital Elevation Model Alberta 1980 1995 60K was compiled from 1:60 000 scale aerial photography using analytical stereoplotters with vegetation and structures excluded. The Digital Elevation Model Northeastern Alberta 1955 1986 50K dataset was created primarily from 1:50 000 scale contour and hydrography data acquired from Natural Resources Canada (NRCAN) with supplementary aerial triangulation points derived from 1:60 000 scale black and white aerial photography dating between 1980 and 1995. The Digital Elevation Model Southwestern Alberta 1979 1996 50K dataset was created primarily from 1:50 000 scale contour and hydrography data from Natural Resources Canada, using Geographic Information System (GIS) processes that recognise the relationship between surface contours and hydrography. The Alberta Provincial Terrain is an ArcGIS terrain dataset that is built from feature classes. Terrains are TIN (Triangulated Irregular Network) -based representations of a surface and must reside inside of a geodatabase. The surface is displayed as triangles with an elevation point at the apex of each triangle. Pyramids are built into the terrain structure to generalize the display of the triangulated surface at different scales. Some analysis can be conducted using terrains but gridded data, such as a raster or a lattice, is often more useful. The Alberta Provincial Terrain is used as a base to generate the Alberta Provincial 25 and 100 Metre Rasters.