Digital Elevation Models

Digital Elevation Models give a mathematical representation of the earth. These large arrays of data are generally used for specialized purposes and require sophisticated tools to deal with them due to the enormous volumes of data.

Using aerial photography and/or satellite imagery, DEMs can be generated at any interval and with any accuracy. A DEM is the essential backbone for any orthoimage but it is also a most useful product in it's own right.

Radio Planning

One of the greatest users of DEM data is the radio planning sector. We have generated terrain data at 50 and 20 meter intervals over large parts of Southern Africa for several of the major cellular telephone and telecommunications companies. (See our clients)

Depending on the needs of our clients, we can create DEMs either over the top of vegetation and ground cover or at ground level (in which case it becomes a digital terrain model or DTM). Usually a ground cover classification (called "clutter") is also required at each spot for which there is an elevation. Over the years we have written software to customize DEM data to many specific formats required by the various radio planning software packages.

Updating orthophotos

Once a precision DEM has been produced for a specific area, new orthophotos can be easily produced. This process simply involves taking new photography of the area and then using the existing DEM to correct the images for topographic distortions. A lot of the labour intensive work is eliminated so costs are considerably reduced. Because terrain elevations very rarely change significantly, it means in turn that repeat mapping is much more economic and data currency is therefore less of an economic burden than the original exercise.

Other Uses

DEMs can also be used to produce other products. One of these is the slope and aspect maps which we create for the farming fraternity. These maps, apart from giving the farmer further insight into the dynamics of his farm, can also be used to determine crop types suitable for certain areas and whether machinery, such as harvesters, can operate on these slopes.

DEM's and DTM's are also applied for :