DTM, Contouring & Volumes

Import COGO points, create a TIN model, then generate contours and apply smoothing and labels.

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  • Fast TIN generation (50,000 points in about 10 seconds).
  • Major and minor contour intervals.
  • Break-line support.
  • Easy contour labeling.
  • Adjustable contour smoothing.
  • Create spot elevations.
  • Calculate volumes.

Contour labeling

Place labels easily on contour lines with a mouse click or by drawing a line across several contour lines to label them all at once.

Creating a Surface

A surface is created from a collection of X,Y,Z, COGO points. Usually you will import the points from an ASCII point file that was created by some other surveying program or data collector.

Surface Boundary

Use a boundary to constrain the surface to a specific area. Simply draw the boundary, then attach it to the surface. All contours and triangles are trimmed to the boundary edge.

DTM boundary before.


DTM boundary after.


Break-lines are used to define features such as ditches, ridges, building footprints and other features where a surface abruptly changes. When present, a break-line forces triangles in the TIN model to be created along the feature instead of across it.

Withoug breaklines.


When break-lines are added to define the top of bank and toe of slope, the triangles correctly follow the ditch. This is essential for proper contour line generation.

With breaklines.


Contours are automatically generated from the underlying TIN model and have the following properties and features. They can include both major and minor contour intervals and a configurable base interval. Smoothing options are also available to smooth out the contours.


Contour Labels

Use your mouse to create individual contour labels. Or, draw a line across several contours and label them all at once.

Contour labels.


Spot Elevations

Spot elevations are directly attached to the surface, so if the surface is changed, the spot elevations are automatically updated. When used with a Volume surface, the spot elevations represent Cut and Fill.

Spot elevations.


Volume Calculations

AGT Topo/DTM can calculate the volume difference between two surfaces. This is ideal for finding the volume of a spoil pile or borrow pit.


Note - This feature is only available in the "Volumes" edition of AGT Topo/DTM


Step 1 - Natural Ground

First, create a surface from shots taken from the ground before any excavating has been done.


Step 2 - Finished Ground

After excavation is complete, take a second set of shots and create a second surface.


Step 3 - Calculate Volume

Now create a "Volume Surface" using the two surfaces above. This will give you the total cut and fill. You can also find and label the cut or fill at any point on the surface. If you turn the contours on, they will represent cut and fill instead of elevation.