Digital Terrain Model File
Adtolla SE which was formally known as Chaos Systems is a software developer which develops software used in Data Coordination, Drawing and Document Management, Project and IT Administration as well as GIS, Mapping and Surveying.
One of the programs that is used for Surveying and Mapping is Topocad, this is a package that is used for Computer Aided Design from the field survey stage up to the finished designs or maps.
Digital Terrain model is a topographic representation of the bare earth,Terrain Model files used by Topocad make use of the .dtm file extension.
How to open .dtm files?
Software to open .dtm files
What are .dtm files