DOCUMENTATION
SYNOPSIS
PACKAGE NAME: surface
AUTHOR: Juan Lorenzo
DATE:
DESCRIPTION:
Version:
USE
NOTES
Examples
GMT NOTES
surface 4.5.7 [64-bit] - Adjustable tension continuous curvature surface gridding
usage: surface [xyz-file] -G<output_grdfile_name> -I<xinc>[u][=|+][/<yinc>[u][=|+]]
-R<west>/<east>/<south>/<north>[r] [-A<aspect_ratio>] [-C<convergence_limit>] [-H[i][<nrec>]]
[-Ll<limit>] [-Lu<limit>] [-N<n_iterations>] ] [-S<search_radius>[m|c]] [-T<tension>[i][b]]
[-Q] [-V[l]] [-Z<over_relaxation_parameter>] [-:[i|o]] [-bi[s|S|d|D[<ncol>]|c[<var1>/...]]] [-f[i|o]<colinfo>]
surface will read from standard input or a single <xyz-file>.
Required arguments to surface:
-G sets output grid file name
-I<xinc>[m|c|e|k|i|n|+][=][/<yinc>[m|c|e|k|i|n|+][=]]
Give increment and append unit (m)inute, se(c)ond, m(e)ter, (k)ilometer, m(i)les, (n)autical miles.
(Note: m,c,e,k,i,n only apply to geographic regions specified in degrees)
Append = to adjust the domain to fit the increment [Default adjusts increment to fit domain].
Alternatively, specify number of nodes by appending +. Then, the increments are calculated
from the given domain and node-registration settings (see Appendix B for details).
Note: If -R<grdfile> was used the increments were set as well; use -I to override.
Note that only gridline registration can be used.
-R specifies the min/max coordinates of data region in user units.
Use dd:mm[:ss] format for regions given in degrees and minutes [and seconds].
Use [yyy[-mm[-dd]]]T[hh[:mm[:ss[.xxx]]]] format for time axes.
Append r if -R specifies the longitudes/latitudes of the lower left
and upper right corners of a rectangular area.
-Rg -Rd are accepted shorthands for -R0/360/-90/90 -R-180/180/-90/90
Alternatively, give a gridfile and use its limits (and increments if applicable).
OPTIONS:
-A<aspect_ratio> = 1.0 by default which gives an isotropic solution.
i.e. xinc and yinc assumed to give derivatives of equal weight; if not, specify
<aspect_ratio> such that yinc = xinc / <aspect_ratio>.
e.g. if gridding lon,lat use <aspect_ratio> = cosine(middle of lat range).
-C<convergence_limit> iteration stops when max abs change is less than <c.l.>
default will choose 0.001 of the range of your z data (1 ppt precision).
Enter your own convergence_limit limit in same units as z data.
-H[i][n_rec] means input/output file has 1 Header record(s) [OFF]
Optionally, append i for input only and/or number of header records
-L constrain the range of output values:
-Ll<limit> specifies lower limit; forces solution to be >= <limit>.
-Lu<limit> specifies upper limit; forces solution to be <= <limit>.
<limit> can be any number, or the letter d for min (or max) input data value,
or the filename of a grid with bounding values. [Default solution unconstrained].
Example: -Ll0 gives a non-negative solution.
-N sets max <n_iterations> in each cycle; default = 250.
-S sets <search_radius> to initialize grid; default = 0 will skip this step.
This step is slow and not needed unless grid dimensions are pathological;
i.e., have few or no common factors.
Append m or c to give <search_radius> in minutes or seconds.
-T adds Tension to the gridding equation; use a value between 0 and 1.
default = 0 gives minimum curvature (smoothest; bicubic) solution.
1 gives a harmonic spline solution (local max/min occur only at data points).
typically 0.25 or more is good for potential field (smooth) data;
0.75 or so for topography. Experiment.
Append B or b to set tension in boundary conditions only;
Append I or i to set tension in interior equations only;
No appended letter sets tension for both to same value.
-Q Query for grid sizes that might run faster than your -R -I give.
-V Run in verbose mode [OFF].
Append l for long verbose
-Z sets <over_relaxation parameter>. Default = 1.4
Use a value between 1 and 2. Larger number accelerates convergence_limit but can be unstable.
Use 1 if you want to be sure to have (slow) stable convergence_limit.
-: Expect lat/lon input/output rather than lon/lat [OFF/OFF].
-bi for binary input. Append s for single precision [Default is double]
Append <n> for the number of columns in binary file(s).
Default is 3 input columns.
-f Special formatting of input/output columns (e.g., time or geographical)
Specify i(nput) or o(utput) [Default is both input and output]
Give one or more columns (or column ranges) separated by commas.
Append T (Calendar format), t (time relative to TIME_EPOCH), f (plain floating point)
x (longitude), y (latitude) to each col/range item.
-f[i|o]g means -f[i|o]0x,1y (geographic coordinates).
(See gmtdefaults man page for hidden GMT default parameters)
(For additional details, see Smith & Wessel, Geophysics, 55, 293-305, 1990.)
CHANGES and their DATES
instantiation##
declare variables## ####
Encapsulated
hash of private variables
sub clear
sub C
outbound grd-format file
sub convergence_limit
outbound grd-format file
sub G
outbound grd-format file
sub inbound
sub outbound
sub grid_spacing
sub I
sub R
sub R
sub Rg
sub L
sub Ll0
sub N
sub S
sub tension
sub T
sub Q
sub verbose
sub V
sub Z
sub bi
sub f
sub Step
sub note