DragonFly On-Line Manual Pages

Search: Section:  

GRDCLIP(1)                   Generic Mapping Tools                  GRDCLIP(1)


NAME

       grdclip - Clipping of range in grid files.


SYNOPSIS

       grdclip input_file.grd -Goutput_file.grd [ -Sahigh/above ] [
       -Sblow/below ] [ -V ]


DESCRIPTION

       grdclip will set values < low to below and/or values > high to above.
       Useful when you want all of a continent or an ocean to fall into one
       color or grayshade in image processing, or clipping of the range of
       data values is required.  above/below can be any number or NaN (Not a
       Number).  You must choose at least one of -Sa or -Sb.

       input_file.grd
              The input 2-D binary grid file.

       -G     output_file.grd is the modified output grid file.


OPTIONS

       -Sa    Set all data[i] > high to above.

       -Sb    Set all data[i] < low to below.

       -V     Selects verbose mode, which will send progress reports to stderr
              [Default runs "silently"].


GRID FILE FORMATS

       By default GMT writes out grid as single precision floats in a COARDS-
       complaint netCDF file format.  However, GMT is able to produce grid
       files in many other commonly used grid file formats and also
       facilitates so called "packing" of grids, writing out floating point
       data as 2- or 4-byte integers. To specify the precision, scale and
       offset, the user should add the suffix =id[/scale/offset[/nan]], where
       id is a two-letter identifier of the grid type and precision, and scale
       and offset are optional scale factor and offset to be applied to all
       grid values, and nan is the value used to indicate missing data.  When
       reading grids, the format is generally automatically recognized. If
       not, the same suffix can be added to input grid file names.  See
       grdreformat(1) and Section 4.17 of the GMT Technical Reference and
       Cookbook for more information.

       When reading a netCDF file that contains multiple grids, GMT will read,
       by default, the first 2-dimensional grid that can find in that file. To
       coax GMT into reading another multi-dimensional variable in the grid
       file, append ?varname to the file name, where varname is the name of
       the variable. Note that you may need to escape the special meaning of ?
       in your shell program by putting a backslash in front of it, or by
       placing the filename and suffix between quotes or double quotes.  The
       ?varname suffix can also be used for output grids to specify a variable
       name different from the default: "z".  See grdreformat(1) and Section
       4.18 of the GMT Technical Reference and Cookbook for more information,
       particularly on how to read splices of 3-, 4-, or 5-dimensional grids.


EXAMPLES

       To set all values > 70 to NaN and all values < 0 to 0 in file data.grd:

       grdclip data.grd -G new_data.grd -Sa 70/NaN -Sb 0/0 -V


SEE ALSO

       GMT(1), grdlandmask(1), grdmask(1), grdmath(1), grd2xyz(1), xyz2grd(1)

GMT 4.5.14                        1 Nov 2015                        GRDCLIP(1)

Search: Section: