table of contents
conflicting packages
GRDPROJECT(l) | GRDPROJECT(l) |
NAME¶
grdproject - Forward and Inverse map transformation of 2-D grd filesSYNOPSIS¶
grdproject in_grdfile -Jparameters -Rwest/east/south/north[ r] [ -A[k|m|n|i|c|p] ] [ -C ] [ -Ddx[m|c][/ dy[m|c]] ] [ -Edpi ] [ -F ] [ -Gout_grdfile ] [ -I ] [ -Mc|i|m|p ] [ -Nnx/ny ] [ -Ssearch_radius ] [ -V ]DESCRIPTION¶
grdproject will do one of two things depending whether -I has been set. If set, it will transform a gridded data set from a rectangular coordinate system onto a geographical system by resampling the surface at the new nodes. If not set, it will project a geographical gridded data set onto a rectangular grid. The new nodes are filled based on a simple weighted average of nearby points. Aliasing is avoided by using sensible values for the search_radius. The new node spacing may be determined in one of several ways by specifying the grid spacing, number of nodes, or resolution. Nodes not constrained by input data are set to NaN.No space between the option flag and the associated arguments. Use upper case for the option flags and lower case for modifiers.
- in_grdfile
- 2-D binary grd file to be transformed.
- -J
- Selects the map projection. Scale is UNIT/degree, 1:xxxxx, or width in
UNIT (upper case modifier). UNIT is cm, inch, or m, depending on the
MEASURE_UNIT setting in .gmtdefaults, but this can be overridden on the
command line by appending the c, i, or m to the scale/width value.
- -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.
OPTIONS¶
- -A
- Force 1:1 scaling, i.e., output (or input, see -I) data are in actual projected meters. To specify other units, append k (km), m (mile), n (nautical mile), i (inch), c (cm), or p (points). Without -A, the output (or input, see -I) are in the units specified by MEASURE_UNIT (but see -M).
- -C
- Let projected coordinates be relative to projection center [Default is relative to lower left corner].
- -D
- Set the grid spacing for the new grid. Append m for minutes, c for seconds.
- -E
- Set the resolution for the new grid in dots pr inch.
- -F
- Toggle between pixel and gridline registration [Default is same as input].
- -G
- Specify the name of the output netCDF grd file.
- -I
- Do the Inverse transformation, from rectangular to geographical.
- -M
- Append c, i, or m to indicate that cm, inch, or meter should be the projected measure unit [Default is set by MEASURE_UNIT in .gmtdefaults]. Cannot be used with -A.
- -N
- Set the number of grid nodes in the new grid.
- -S
- Set the search radius for the averaging procedure [Default avoids aliasing].
- -V
- Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].
EXAMPLES¶
To transform the geographical grid dbdb5.grd onto a pixel Mercator grid at 300 dpi, runRESTRICTIONS¶
The boundaries of a projected (rectangular) data set will not necessarily give rectangular geographical boundaries (Mercator is one exception). In those cases some nodes may be unconstrained (set to NaN). To get a full grid back, your input grid may have to cover a larger area than you are interrested in.SEE ALSO¶
gmt(1gmt), gmtdefaults(1gmt), mapproject(1gmt)1 Jan 2004 |