Digital terrain models

A digital terrain model, or DTM, is a way of representing a surface in a 3-dimensional computerized form. A DTM is created from string data by forming a set of non-overlapping, adjacent triangles between points in a string file.

You can create a DTM from any set of 3-dimensional coordinates. The Y and X coordinates are normally northings and eastings with the Z coordinates being any quantity.

For example,

• if the Z coordinates are elevations, the resulting DTM represents a physical surface, such as the natural ground surface, top and bottom of a coal seam, water table elevation etc.
• if the Z coordinates are mineral grades, contaminant concentrations, etc., then the high points and low points in the resulting DTM represent points of high and low grades/concentrations.
• the coordinates may be seam thicknesses, or overburden ratios or any other calculated quality parameter.

Once a DTM has been created, you can view it in Graphics, extract contours from it, take sections through it or use it for volume calculations.