| What is a digital elevation model? | | | | satellites to create maps of areas of 10 |
| Digital elevation models, or DEMs, are digital | | | | kilometers per side. Two passes are all that is |
| representations of a geographic region's | | | | required to produce one such map, which usually |
| topographical (or surface terrain) features. They | | | | has a resolution of 10 meters. |
| are also referred to sometimes as "digital terrain | | | | Digital image correlation is another, albeit older and |
| models" or DTMs. However, unlike DTMs, DEMs | | | | less powerful, method of producing digital |
| offer continuous elevation data on an area of land. | | | | elevation models. This method combines two |
| DTMs like contour line maps and topographical | | | | optical images taken from an airplane or earth |
| maps are not considered, for this reason, DEMs. | | | | observation satellite during a single pass. These |
| Most digital elevation models are constructed using | | | | two images, taken from different angles, create a |
| remotes sensing techniques and tools, like satellite | | | | more complete data set for a particular |
| radar and airplane imaging. However, in some | | | | geographical area. The first usable set of elevation |
| cases data procured via the traditional method of | | | | data was produced using this method. The satellite |
| direct land surveying is also implemented into the | | | | used was SPOT 1, back in 1986. |
| creation of DEMs. Some of the most common | | | | Lastly, there's the direct land survey. This method |
| uses of DEMs are in what is known as digital | | | | has been used for over a hundred years and data |
| information systems (DIS). These are systems | | | | gathered with this method is still used in digital |
| used by governments and large industries to | | | | elevation models today, especially for mountainous |
| assess and analyze the conditions of a given | | | | regions which are difficult to map accurate using |
| region. However DEMs and DIS is more and more | | | | remote sensing techniques. |
| being used in the field of mobile consumer | | | | Current Uses |
| electronics that implement location bases services | | | | Digital elevation maps are being used today in a |
| and technology. | | | | variety of fields. Among these are GPS services |
| Methods of creating DEMs | | | | and other consumer location based services, flight |
| The most sophisticated and powerful tool for | | | | simulators, land assessment, precision farming, |
| coming up with digital elevation models is called | | | | intelligent transportation systems and advanced |
| interferometric synthetic aperture radar. It works | | | | driver assistance systems. |
| by using radar images taken from orbiting | | | | |