Compudrape Extension

The Compudrape extension drapes any potential field profile or gridded data to any reference surface and performs height continuation on aeromagnetic profile data. It enables you to perform height continuation on aeromagnetic profile data.

Compudrape performs height continuation on aeromagnetic profile data to transform it from the original magnetic field on an arbitrary observation surface to the magnetic field on a new surface of specified height. The primary uses are to drape barometric or loose drape surveys to a tight drape, drape over the basement surface, transform drape-flown surveys to barometric and apply height corrections to minimize line-to-line effects.

In areas with steep topography it is difficult for survey aircraft to maintain a constant nominal height on the land. This causes large variations in the
distance between the magnetic sensor and the ground (from 100 to 1000 m.), making it very difficult to process the data.

Compudrape corrects this effect by generating a magnetic grid that simulates the result that had been reached if the airplane had maintained a constant height.

The extension includes 1D and 2D functionality. The 1D function is most useful for removing the effects of variation in terrain clearance from line-to-line and/or at traverse-tie line intersections.

Compudrape was designed to perform loose drape or barometric to drape transformation as its primary task, so the elevation channel is the magnetic sensor elevation above sea level. The topography channel is the topography (i.e., sensor terrain clearance above ground subtracted from sensor elevation above sea level). The new observation height value is the desired constant drape height above ground.

To perform a drape to barometric transformation, elevation and topography channels change their meaning. The elevation channel is now a channel of the sensor terrain clearance (i.e., the radar altimeter channel). The topography channel is sea level (i.e., the channel contains constant values of 0). The new observation height value is the serried constant barometric altitude above sea level. Compudrape was developed by the Paterson, Grant & Watson Limited.