GRDTRACK

Section: Misc. Reference Manual Pages (l)
Updated: DATE
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NAME

grdtrack - Sampling of a 2-D grdfile along 1-D trackline  

SYNOPSIS

grdtrack xyfile -Ggrdfile [ -H ] [ -L ] [ -M[flag] ] [ -Q ] [ -V ] [ -: ]  

DESCRIPTION

grdtrack reads a 2-D binary grdfile and an ASCII table (from file or standard input) with (x,y) positions in the first two columns (more columns may be present). It then samples the gridded data set at the positions in the ASCII file and outputs the ASCII file with the sampled values added as a new column. A bicubic [Default] or bilinear interpolation is used to sample the grid. Free boundary conditions are assumed (curvature and 3rd normal derivative is zero).
xyfile
This is an ASCII file where the first 2 columns hold the (x,y) positions where the user wants to sample the 2-D data set.
-G
grdfile is a 2-D binary grd file with the function f(x,y).
 

OPTIONS

No space between the option flag and the associated arguments. #include "explain_-H.txt"
-L
Indicates that the x column contains longitudes, which may differ from the region specified in grdfile by [multiples of] 360 degrees [Default assumes no periodicity].
-M
Multiple segment file. Segments are separated by a record whose first character is <flag>. [Default is '>'].
-Q
Quick mode. Use bilinear rather than bicubic interpolation. #include "explain_-V.txt"
-:
Toggles between (longitude,latitude) and (latitude,longitude) input/output. [Default is (longitude,latitude)]
 

EXAMPLES

To sample the file hawaii_topo.grd along the SEASAT track track_4.xyg (An ASCII table containing longitude, latitude, and SEASAT-derived gravity, preceeded by one header record), try

grdtrack track_4.xyg -Ghawaii_topo.grd -H > track_4.xygt  

BUGS

All the peripheral nodes needed to evaluate the interpolation must be real in order to return a sampled value. If any of these are NaN then NaN is returned.  

SEE ALSO

gmt, surface, sample1d #include "refs.i"


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
BUGS
SEE ALSO

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