Digital Elevation Model data record the terrain height variations from the processed point-located data recorded on an airborne geophysical survey.  The aircraft altimeter data records the height of the aircraft above the ground and the aircraft GPS records the height of the aircraft above the ellipsoid.  Subtracting the two values enables the height of the terrain beneath the aircraft relative to the ellipsoid to be calculated.  This ellipsoidal terrain height is corrected for the variation between the ellipsoid and the geoid (the n-value correction) to produce terrain heights relative to sea level.

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

This paper was presented at SGEG Conference, Canberra, January 1997

This paper was presented at SGEG Conference, Canberra, January 1997

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

Total magnetic intensity data measures variations in the intensity of the Earth's magnetic filed caused by the contrasting content of rock-forming minerals in the Earth's crust. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

Total magnetic intensity data measures variations in the intensity of the Earth's magnetic filed caused by the contrasting content of rock-forming minerals in the Earth's crust. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.