Mine wall face
Figure 1. Image of the section of the pit to be surveyed
This system was developed to provide accurate production figures on a hourly basis. The earth moving contractor was paid for the volume of material removed from an open cut mine. Usually the volume mined is established by a traditional survey of the pit on a monthly basis. Our client wanted much more frequent updates of the production figures in order to evaluate the efficiencies of equipment and shifts, etc.
Computed 3D points and DTM Triangles
Figure 2. Display of computed 3D points and DTM triangles

This was the first system ever built on the 3DM technology, back in 1997. The system used a minimum of 4 control points to determine the exterior orientations of the cameras. The pit had a diameter of approximately 250 m and a depth of 30 m. Two CCD cameras were set up on the opposite rim of the pit. This allowed an area of approximately 50m x 50m to be surveyed. The system computed a digital terrain model (DTM) of some 600 points every 3 minutes. It also computed and displayed the volume of material removed from the test area.

Further developments in the 3DM technology have led to improved image matching and centroiding software being included.