This is the command gmtgravmag3dgmt that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
gmtgravmag3d - Compute the gravity/magnetic effect of a body by the method of Okabe
gmtgravmag3d [[d]xyz_file/vert_file[/m]]|[r|s]raw_file [ density ] [ ] [ thickness ] [
xy_file ] [ outputgrid ] [ f_dec/f_dip/m_int/m_dec/m_dip ] [ z_observation ] [ radius ] [
level ] [ [level] ] [ -fg]
Note: No space is allowed between the option flag and the associated arguments.
gmtgravmag3d will compute the gravity or magnetic anomaly of a body described by a set of
triangles. The output can either be along a given set of xy locations or on a grid. This
method is not particularly fast but allows computing the anomaly of arbitrarily complex
Sets body density in SI. This option is mutually exclusive with -H.
Sets parameters for computing a magnetic anomaly. Use f_dec/f_dip to set the
geomagnetic declination/inclination in degrees. m_int/m_dec/m_dip are the body
magnetic intensity declination and inclination.
Provide locations where the anomaly will be computed. Note this option is mutually
exlusive with -G.
Output the gravity or magnetic anomaly at nodes of this grid file.
-R[unit]xmin/xmax/ymin/ymax[r] (more ...)
Specify the region of interest.
Give either names of xyz[m] and vertex files or of a raw or stl file defining a
close surface. In the first case append a d immediately after -T and optionally a
/m after the vertex file name. In the second case append a r or a s immediately
after -T and before the file name. A vertex file is a file with N rows (one per
triangle) and 3 columns with integers defining the order by which the points in the
xyz file are to be connected to form a triangle. The output of the program
triangulate comes in this format. The optional /m instructs the program that the
xyzm file has four columns and that the fourth column contains the magnetization
intensity (plus signal), which needs not to be constant. In this case the third
argument of the -H option is ignored. A raw format (selected by the r flag is a
file with N rows (one per triangle) and 9 columns corresponding to the x,y,x
coordinates of each of the three vertex of each triangle. Alternatively, the s
flag indicates that the surface file is in the ASCII STL (Stereo Lithographic)
format. These two type of files are used to provide a closed surface.
-V[level] (more ...)
Select verbosity level [c].
give layer thickness in m [Default = 0 m]. Use this option only when the triangles
describe a non-closed surface and you want the anomaly of a constant thickness
sets level of observation [Default = 0]. That is the height (z) at which anomalies
search radius in km. Triangle centroids that are further away than radius from
current output point will not be taken into account. Use this option to speed up
computation at expenses of a less accurate result.
level of reference plane [Default = 0]. Use this option when the triangles describe
a non-closed surface and the volume is defined from each triangle and this
reference level. An example will be the hater depth to compute a Bouguer anomaly.
-fg Geographic grids (dimensions of longitude, latitude) will be converted to meters
via a "Flat Earth" approximation using the current ellipsoid parameters.
-^ or just -
Print a short message about the syntax of the command, then exits (NOTE: on Windows
use just -).
-+ or just +
Print an extensive usage (help) message, including the explanation of any
module-specific option (but not the GMT common options), then exits.
-? or no arguments
Print a complete usage (help) message, including the explanation of options, then
Print GMT version and exit.
Print full path to GMT share directory and exit.
GRID DISTANCE UNITS
If the grid does not have meter as the horizontal unit, append +uunit to the input file
name to convert from the specified unit to meter. If your grid is geographic, convert
distances to meters by supplying -fg instead.
Suppose you ...
gmt gmtgravmag3d ...
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