grdinfo(1) [debian man page]

GRDINFO(l)																GRDINFO(l)

NAME

       grdinfo - Get information about the contents of a 2-D grd file

SYNOPSIS

       grdinfo grdfiles [ -C ] [ -D ] [ -F ] [ -L1 ] [ -L2 ] [ -M ] [ -V ]

DESCRIPTION

       grdinfo reads a 2-D binary grd file and reports various statistics for the (x,y,z) data in the grdfile. The output information contains the
       minimum/maximum values for x, y, and z, where the min/max of z occur, the x- and y-increments, and  the	number	of  x  and  y  nodes,  and
       [optionally] the mean, standard deviation, and/or the median, L1 scale of z, and number of nodes set to NaN.

       grdfile
	      The name of one or several 2-D grd files.

OPTIONS

       No space between the option flag and the associated arguments.

       -C     Formats  the report using tab-separated fields on a single line. The output is w e s n z0 z1 dx dy nx ny [ x0 y0 x1 y1 ] [ med scale
	      ] [ mean std rms] [n_nan].  The data in brackets are output only if the corresponding options -M, -L1, -L2, and -M are used, respec-
	      tively.

       -D     Report grid domain and x/y-increments using dd:mm:ss[.fff] notation [Default is decimal].  Does not apply to the -C option.

       -F     Report grid domain and x/y-increments world mapping format [Default is generic].	Does not apply to the -C option.

       -L1    Report median and L1 scale of z (L1 scale = 1.4826 * Median Absolute Deviation (MAD)).

       -L2    Report mean and standard deviation of z.

       -M     Find and report the location of min/max z-values, and count and report the number of nodes set to NaN, if any.

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

EXAMPLES

       To obtain all the information about the data set in file hawaii_topo.grd, try

       grdinfo -L1 -L2 -M hawaii_topo.grd

SEE ALSO

       gmt(1gmt), grd2cpt(1gmt), grd2xyz(1gmt), grdedit(1gmt)

								    1 Jan 2004								GRDINFO(l)

GRDSAMPLE(l)															      GRDSAMPLE(l)

NAME

       grdsample - Resample a grd file onto a new grid

SYNOPSIS

       grdsample  in_grdfile -Gout_grdfile [ -F ] [ -Idx[m|c][/dy[m|c]] ] [ -Lflag ] [ -Nnx/ny ] [ -Q ] [ -Rwest/east/south/north[r] ] [ -T ] [ -V
       ]

DESCRIPTION

       grdsample reads a grdfile and interpolates it to create a new grdfile with either: a different registration (-T); or,  a  new  grid-spacing
       (-I) or number of nodes (-N), and perhaps also a new sub-region (-R). Interpolation is bicubic [Default] or bilinear (-Q) and uses boundary
       conditions (-L).  Note that using (-R) only is equivalent to grdcut or grdedit -S. grdsample safely creates a fine mesh from a coarse  one;
       the converse may suffer aliasing unless the data are filtered using grdfft or grdfilter.

       in_grdfile
	      The name of the input 2-D binary grd file.

       -G     The name of the output grd file.

OPTIONS

       No space between the option flag and the associated arguments.

       -F     Force pixel registration. [Default is grid registration].

       -I     x_inc [and optionally y_inc] is the grid spacing. Append m to indicate minutes or c to indicate seconds.

       -L     Boundary condition flag may be x or y or xy indicating data is periodic in range of x or y or both set by -R, or flag may be g indi-
	      cating geographical conditions (x and y are lon and lat). [Default uses "natural" conditions (second partial  derivative	normal	to
	      edge is zero).]

       -N     Specify number of columns nx and rows ny of new grid.

       -Q     Quick mode, use bilinear rather than bicubic interpolation.

       -R     west,  east,  south,  and  north specify the Region of interest. To specify boundaries in degrees and minutes [and seconds], use the
	      dd:mm[:ss] format. Append r if lower left and upper right map coordinates are given instead of wesn.

       -T     Translate between grid and pixel registration while keeping -R and -I the same; if input is grid-registered, output will	be  pixel-
	      registered and vice-versa. The input file determines -R, -I and -N so no other options are necessary (except possibly -L or -Q).

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

HINTS

       If  an  interpolation point is not on a node of the input grid, then a NaN at any node in the neighborhood surrounding the point will yield
       an interpolated NaN. Bicubic interpolation [default] yields continuous first derivatives but requires a neighborhood of 4 nodes by 4 nodes.
       Bilinear interpolation [-Q] uses only a 2 by 2 neighborhood, but yields only zeroth-order continuity. Use bicubic when smoothness is impor-
       tant. Use bilinear to minimize the propagation of NaNs.

EXAMPLES

       To resample the 5 x 5 minute grid in hawaii_5by5_topo.grd onto a 1 minute grid, try

       grdsample hawaii_5by5_topo.grd -I1m -Ghawaii_1by1_topo.grd

       To translate the gridline-registered file surface.grd to pixel registration, try

       grdsample surface.grd -T -Gpixel.grd

SEE ALSO

       gmt(1gmt), grdedit(1gmt), grdfft(1gmt), grdfilter(1gmt)

								    1 Jan 2004							      GRDSAMPLE(l)