Geophysical Software
Geophysical Software is a small firm focused largely upon developing application
software for potential field data reduction and interpretation. At present,
most applications are in the field of gravity field interpretation and
data reduction, particularly in the area of high-precision, digital
terrain
corrections for gravimeter stations. Software permitting the user to
correct gravity stations using a variety of different types of terrain
data is available.
Products and Services
InnerTC
Two types of gravity terrain correction software are offered. One, called
InnerTC,
provides terrain corrections for gravity data using the standard 30-meter
Digital Elevation Models that are produced by the U. S. Geological Survey.
InnerTC permits gravity terrain corrections to be made from very close to the gravity
station to a distance of a few kilometers. It provides extremely accurate
terrain corrections and is limited in accuracy only by the resolution and
accuracy of the basic Digital Elevation Model used. The basic methodology
is described in Cogbill (1990).
Documentation
for the routine is available here for those wishing more detailed information.
Features
InnerTC permits one to calculate extremely accurate gravity terrain
corrections, provided that the DEMs are an accurate representation of the
nearby terrain. Some of the features of InnerTC are:
- Uses either the actual elevations of a gravity station or interpolated
elevations.
- Auxiliary elevation data can be provided by the user.
- The capability to account for a bias between elevations accompanying the
gravity stations and the elevations provided on a DEM is provided.
- A wide selection of input file formats is supported.
- The locations of input gravity data are supplied in geographic coordinates.
RasterTC
Because the 30-m USGS DEMs are, of course, only available in the United States, and
because some users may have special, possibly very high-resolution, digital terrain models,
RasterTC is offered. RasterTC permits a user to provide
a Digital Terrain Model in the form of one or more terrain grids. Such grid(s) can be provided
in different resolutions, permitting, for example, grids having very fine spatial
resolution to be used close to a set of gravity stations, while coarser grids can be
used at greater distances, thus improving computational efficiency.
RasterTC is very similar to InnerTC. Differences are
primarily in the type of terrain data provided.
Documentation is available here, as well.
LaserTC
A related product is LaserTC. LaserTC was originally designed
to provide high-precision terrain corrections for topography occurring
within the first 50 meters of a gravity station. Digital terrain data so
close to a gravity station can now be readily acquired in the field using
newly available, reflectorless laser rangefinders. Such rangefinders
permit a detailed digital terrain data to be acquired in the vicinity of
a gravity station within only 2-3 minutes, permitting the gravity meter
operator to acquire the terrain data needed for LaserTC at the same
time as the gravity measurements are made.
Although LaserTC was originally designed for use as described
above, it is quite general; thus, close-in terrain corrections for gravity
stations can be calculated using virtually any type of user-supplied terrain
data. For example, terrain corrections can be readily calculated using
topographic data consisting of digitized elevation contours. Documentation
for LaserTC is available for those wishing more detailed information
about how the program works.
Pricing
Both InnerTC, RasterTC, and LaserTC are
provided as a terrain correction package. Pricing for the package is as follows:
- For commercial licenses, the cost
of the package is $1099 US.
- For governmental, university, or other non-profit institutions, the price
is of a license is $549 US.
- For students, the price is $275 US; a
letter, e-mail, or fax with information verifying the status of the student
must be sent.
Contact Information
For more detailed information regarding pricing, product availability,
services offered, or future products, please contact us by telephone or e-mail:
References Cited
Cogbill, Allen H. (1990) Gravity terrain corrections
calculated using Digital Elevation Models, Geophysics, 55(1),
102-106.
Lyman, Gregory D., Carlos L. V. Aiken, Allen Cogbill, Mamadou Balde,
and Chet Lide (1997) Terrain mapping by reflectorless laser rangefinding
systems for inner zone gravity terrain corrections, to be presented
at the 67th Annual Meeting of the Society of Exploration Geophysicists,
November 2-7, 1997, Dallas, Texas.
Plouff, Donald (1966) Digital terrain corrections
based upon geographic coordinates [abstract], Geophysics, 31,
1208.
Last updated: 21 June 2007
