An elevation model is a digital representation of the earth’s terrain. A digital elevation model (DEM) is an important component of many geospatial projects and particularly for engineering, energy and academic studies. In order to create a DEM, stereoscopic data – similar to what fuels a 3D plasma TV – is required. Here at Apollo Mapping, we can source the raw data required for an elevation model that satisfies both the monetary constraints and geospatial needs of your project.

Depending on the desired outcomes of your project, the earth’s surface can be represented in one of two manners:

• As a digital surface model (DSM) which includes surface features such as vegetation and human-made structures.
• As a digital terrain model (DTM) whereby the surface features in a DSM have been removed so that it represents bare earth.

In many instances, elevation models will exceed a vertical accuracy of 1-meter (m) LE90 and a horizontal accuracy of 2-m CE90 – this assumes the use of ground control points.

Deliverables

An elevation model can be delivered in two formats:

• As a raster grid where each pixel has a known footprint on the ground (e.g., 1 m by 1 m) with a known elevation (e.g., 525 m).
• As a vector file with continuous lines, or contours, at known increments (e.g., spaced apart every 5 m) with a known elevation (e.g., 110 m).

Elevation Model Add-Ons

The raw data used to create an elevation model can also provide valuable information and product enhancements if processed correctly:

• Breaklining – addition of elevation information along linear features with an abrupt change in gradient (such as a gulley, ridge or stream channel) that are often missed in automated DEM creation
• Feature Extraction – utilize multiple look angles offered by stereo data to develop accurate GIS layers, for instance of building footprints, edges of roads and tree crowns
• Volume Calculation – determine accurate volumes of features on the earth’s surface, for example of coal piles and other mine tailings
• Line of Sight Determination – map the various locations and/or features that are visible from a central point, this data is important in airport construction and wind/solar farm placement
• 3D Modeling – create a realistic view of the earth’s surface and the features on it, often times with animated fly-throughs for efficient site planning and innovative multimedia presentations