Download the Gravity Correction Manual as PDF

Gravity Corrections

QCTool has an additional suite of gravity processing and correction techniques. Tools for drift, latitude, free-air and full Bouguer, Isostatic and Eötvös corrections.
Gravity Data Correction Manual(PDF, 1.8 MB)

Bouguer Corrections(PDF, 411 KB)

Key Features

Import

Gravity is imported and merged to carry out further gravity correction - measured data in instrument dump formats or ASCII XYZ or .CSV format.

Meter Calibration Correction

This correction provides conversion of gravity instrument readings into milliGals. Two types of Meter Calibration Correction are available - one for older meters where a constant instrument scale factor is used to multiply instrument readings by and the other for newer meters featuring a more complex relationship between the instrument readings and milliGals. In the latter case, a table of factors rather than a single constant is used. QCTool provides import of this table as well.

Tide Correction

This correction uses a special Tidal Algorithm. When computed, it is added as a separate channel to your file, to be further applied to the instrument readings with the help of the embedded Calculator. This algorithm is maintained up to date with the latest equations

Drift Correction

This correction is based on several loop ties, allowing approximation of a more complex drift. Drift is calculated based on the error between the first and last reading in each loop. Within day and cross day drift corretions are provided. A special tool has been developed to automatically perform quality control on repeat measurements that are to be used in your drift corrections.

Absolute Gravity

Absolute gravity is calculated based on the known reference station and your data that have previously undergone drift correction.

Latitude, Free Air, and Bouguer slab, Bullard B, Atmospheric Correction

The Latitude, Free Air and Bouguer algorithms are available through the same simple interface. The newly calculated corrections can be added as new channels or overwritten into the existing channels of your file. Then the corrections can be applied using the embedded Calculator.

Terrain Correction

Two kinds of terrain correction are available - Regional and Local. The regional terrain correction is based on regional topography grids that can be created from DEM files in BIL, GEOTIFF, GTOPO30 and CDED format through a 3-step wizard in QCTool. Any regional grid format may be used if it can be converted to .BIL, GEOTIFF, ASCII or binary XYZ format. The local terrain correction can be performed with your surveyed GNSS dataa but also the more traditional surveyed data at 3 points surrounding your gravity stations may be applied.

Eötvös, Isostatic Corrections see gravity correctinos manual above