Ubuntu Manpage: gmtgravmag3d - Compute the gravity/magnetic effect of a body by the method of Okabe

Provided by: gmt-common_5.2.1+dfsg-3build1_all

NAME

       gmtgravmag3d - Compute the gravity/magnetic effect of a body by the method of Okabe

SYNOPSIS

       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.

DESCRIPTION

       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 shapes.

REQUIRED ARGUMENTS

-Cdensity
Sets body density in SI. This option is mutually exclusive with -H.

-Hf_dec/f_dip/m_int/m_dec/m_dip
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.

-Fxy_file
Provide locations where the anomaly will be computed. Note this option is mutually exlusive with
-G.

-Goutgrid
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.

-T[[d]xyz_file/vert_file[/m]]|[r|s]raw_file]
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.

OPTIONAL ARGUMENTS

       -V[level] (more ...)
              Select verbosity level [c].

       -E[thickness]
              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 layer.

       -L[z_observation]
              sets level of observation [Default = 0]. That is the height (z) at which anomalies are computed.

       -Sradius
              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.

       -Z[level]
              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 exits.

       --version
              Print GMT version and exit.

       --show-datadir
              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.

EXAMPLES

       Suppose you ...

              gmt gmtgravmag3d ...

REFERENCE

       Okabe, M., Analytical expressions for gravity anomalies due to polyhedral  bodies  and  translation  into
       magnetic anomalies, Geophysics, 44, (1979), p 730-741.

COPYRIGHT

       2015, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe

5.2.1                                           January 28, 2016                              GMTGRAVMAG3D(1gmt)