حسب تعريف ال wikipedia
http://en.wikipedia.org/wiki/Digital_elevation_model
A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. It is also widely known as a digital terrain model (DTM). A DEM can be represented as a raster (a grid of squares) or as a triangular irregular network. DEMs are commonly built using remote sensing techniques, however, they may also be built from land surveying. DEMs are used often in geographic information systems, and are the most common basis for digitally-produced relief maps.
حسب تعريف اخر dtm
http://www.osni.gov.uk/productguide_...rain_model.pdf
What is a Digital Terrain Model?
A Digital Terrain Model (DTM) is a digital file providing a highly detailed representation of the topographical
(i.e. relief) variations in the Earth’s surface. Combined with other digital data, such as maps or orthophotographs, it can provide a 3D image of the land surface. Consisting of terrain elevations for ground positions at regularly spaced horizontal intervals, the added dimension and visualisation offered by a DTM can help in many
decision-making processes.
وحسب استنتاجي للتعاريف والمعلومات عنها
فأنني استنتج مالي
فأن هناك نوع من الاختلاف فمصدر DTM هو شبكة من النقاط الموزعة بانتظام ولكل نقطة ارتفاع
اما DEM ليس بالضرورة ان تكون النقاط موزعة بالنتظام
DTM هي تقنية من وسائل ال photogrametry
رد مع اقتباس