Changes

==Interpretive processing techniques==

==Interpretive processing techniques==

After obtaining either free air gravity or [[Wikipedia:Bouguer anomaly|Bouguer]] gravity, subsequent processing may be needed to enhance or suppress various geologic effects. For example, Bouguer gravity naturally has lower values over higher elevations and higher values over deep ocean basins because of variations in the crustal thickness, or ''isostasy''. An isostatic correction to suppress this deep effect can be made if the data set is large enough.<ref name=ch15r3>Chapin, D., A., 1996b, A deterministic approach towards computing isostatic gravity residuals: case history from South America: Geophysics, vol. 61, no. 4, p. 1022–1033, DOI: [http://library.seg.org/doi/abs/10.1190/1.1444024 10.1190/1.1444024].</ref> In smaller data sets, typically a long-wavelength surface can be removed from the data to suppress this effect. Other interpretive processing to enhance certain anomalies includes the following:

After obtaining either free air gravity or [[Wikipedia:Bouguer anomaly|Bouguer]] gravity, subsequent processing may be needed to enhance or suppress various geologic effects. For example, Bouguer gravity naturally has lower values over higher elevations and higher values over deep ocean basins because of variations in the crustal thickness, or ''[http://www.hko.gov.hk/education/edu06nature/ele_isostasy_e.htm isostasy]''. An isostatic correction to suppress this deep effect can be made if the data set is large enough.<ref name=ch15r3>Chapin, D., A., 1996b, A deterministic approach towards computing isostatic gravity residuals: case history from South America: Geophysics, vol. 61, no. 4, p. 1022–1033, DOI: [http://library.seg.org/doi/abs/10.1190/1.1444024 10.1190/1.1444024].</ref> In smaller data sets, typically a long-wavelength surface can be removed from the data to suppress this effect. Other interpretive processing to enhance certain anomalies includes the following:

* Band-pass filtering—selecting a range of wavelengths to display

* Band-pass filtering—selecting a range of wavelengths to display

* Derivatives—edge-enhancing processes that tend to emphasize the shorter wavelength anomalies

* Derivatives—edge-enhancing processes that tend to emphasize the shorter wavelength anomalies

* Upward/downward continuation—a process that attenuates or deattenuates data to simulate what might be observed at different vertical datums

* Upward or downward continuation—a process that attenuates or deattenuates data to simulate what might be observed at different vertical datums

Collectively, these are all termed ''regional/residual operators''. Many different types are useful for different purposes.

Collectively, these are all termed ''regional or residual operators''. Many different types are useful for different purposes.

==See also==

==See also==