Characteristics of terrain models
Cartographic terrain or relief models are three-dimensional representations of a part of the earth's surface. They convey an immediate and direct impression of a landscape, and are much easier to understand than two-dimensional maps for most people. A plane two-dimensional map can only portray the third dimension by limited cartographic devices, such as contour lines, relief shading and special signatures. These are rather abstract constructions, and require training and imagination from the map reader. This is especially true for representations of mountainous regions with steep slopes and rock faces is limited in conventional maps. Alternative paintings or photographs of a rock face are only able to provide the view of one single point. Only with terrain models it is possible to entirely depict the third dimension. Particularly on large-scale models, a huge amount of topographic details and information can be shown.
There are a lot of applications for relief models, such as for teaching and education on all levels of training: for primary schools as well as for universities, in the army just as for information of the public about infrastructure projects; but also to facilitate urban and regional planning, or to study geological and geomorphological phenomenona.
In the early time of topographic relief depiction, terain models were the easiest way to see the world from the bird’s eye view and the only one, where the observer could choose his position freely. Aircrafts didn’t exist beside balloons, and climbing on a mountain is only possible, where mountains exist. But still today, terrain models allow for the calm study of landscapes independently from weather conditions. In contrast to virtual models generated by a computer, the physically present model is easier and faster to understand.
Major disadvantages of a terrain model are the amount of required space and the difficulty to transport because of the extent and particularly of the weight. Plaster models are most affected by these disadvantages, whereas thermoplastic models are relatively easy to transport. Another disadvantage is their production cost in both time and resources. New technologies may be able to shorten the production time and to reduce the costs. Unfortunately, these faster and cheaper techniques do not yet reach the quality of the best handmade plaster models.