DTM

Digital Terrain Modelling (DTM) generates a mathematical model from a random set of data points that have X, Y and Z values. It uses Delauney triangulation. This creates a mesh of triangles by drawing lines between data points. The triangles are as equiangular as possible and the original data points are connected so no triangle sides are intersected by other triangles. The triangulation network is unique. In other words, the same set of triangles will be generated regardless of how the data points are sorted (in the file).

Once you have created a DTM, you can calculate the Z value for any point within the bounds of the model. This enables the surface to be contoured and a volume to be calculated between the surface and a plane (or between the surface and another surface).

Other contouring methods generate a grid of points with the Z values of the grid nodes calculated from the surrounding data. This has the effect of the smoothing the data. Because DTMs use the actual points in the file to define the triangles, the original data is honoured.

DTMs are most commonly associated with topographic data, with Z being elevation. This will allow pit or stockpile volumes to be calculated, or contour maps to be plotted. However the Z value can also be ore grades or seam thickness and, as a result, DTMs have widespread use. They are often useful in pit optimisation and ore body estimation.

The Earthworks product, Viewpoint, includes a driver to load Micromine DTM files. This allows 3D visualisation of the surface model.

The following DTM functions are available:

Create Surface

Create generates a DTM from a file containing points with X, Y and Z coordinates. The output file is used by the other DTM functions. The DTM may be contoured, and the contours written to a string file, as part of the create process.

Create Plane from Points

Using the Create from Points function, a constraint file is defined that will clip the triangle edges. Z values in the constraint file are recalculated and these are included during the surface creation.

The following functions operate on an existing DTM file:

Volumes

Calculates volumes between two DTMs or between one DTM and a user defined horizontal plane.

Contours

Contours an existing DTM.

Generate Boundary Strings

Generates the boundary strings from a nominated wireframe. This is done by detecting the edges of the triangulation.

Seam Thickness

Uses two existing DTMs, which define the top and bottom of a seam, to generate a new DTM which has the seam thickness as the Z value.

Generate Z Values

Uses an existing DTM to calculate the Z values for data points that only have X and Y coordinates.

Assign

Determine whether points in a file are above, below or outside the limits of the created DTM.

DTM->File

Converts a DTM file to a string file.

DTM->Faces File

Converts a DTM file to a file that can be used by the AutocadÔ Faces command.