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<HTML>
<HEAD>
<TITLE>grdproject</TITLE>
</HEAD>
<BODY>
<H1>grdproject</H1>
<HR>
<PRE>
<!-- Manpage converted by man2html 3.0.1 -->
grdproject - Forward and Inverse map transformation of 2-D
grd files
</PRE>
<H2>SYNOPSIS</H2><PRE>
<B>grdproject</B> <I>in</I><B>_</B><I>grdfile</I> <B>-J</B><I>parameters</I>
<B>-R</B><I>west/east/south/north</I>[<B>r</B>] [ <B>-A</B>[<B>k|m|n|i|c|p</B>] ] [ <B>-C</B> ] [
<B>-D</B><I>dx</I>[<B>m|c</B>][/<I>dy</I>[<B>m|c</B>]] ] [ <B>-E</B><I>dpi</I> ] [ <B>-F</B> ] [ <B>-G</B><I>out</I><B>_</B><I>grdfile</I> ] [
<B>-I</B> ] [ <B>-Mc|i|m|p</B> ] [ <B>-N</B><I>nx/ny</I> ] [ <B>-S</B><I>search</I><B>_</B><I>radius</I> ] [ <B>-V</B> ]
</PRE>
<H2>DESCRIPTION</H2><PRE>
<B>grdproject</B> will do one of two things depending whether <B>-I</B>
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 <I>search</I><B>_</B><I>radius</I>.
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 associ
ated arguments. Use upper case for the option flags and
lower case for modifiers.
<I>in</I><B>_</B><I>grdfile</I>
2-D binary grd file to be transformed.
<B>-J</B> 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 MEA
SURE_UNIT setting in .<A HREF="gmtdefaults.html">gmtdefaults</A>, but this can be
overridden on the command line by appending the c,
i, or m to the scale/width value.
<B>CYLINDRICAL</B> <B>PROJECTIONS:</B>
<B>-Jc</B><I>lon0/lat0/scale</I> (Cassini)
<B>-Jj</B><I>lon0/scale</I> (Miller)
<B>-Jm</B><I>scale</I> (Mercator - Greenwich and Equator as ori
gin)
<B>-Jm</B><I>lon0/lat0/scale</I> (Mercator - Give meridian and
standard parallel)
<B>-Joa</B><I>lon0/lat0/azimuth/scale</I> (Oblique Mercator -
point and azimuth)
<B>-Job</B><I>lon0/lat0/lon1/lat1/scale</I> (Oblique Mercator -
two points)
<B>-Joc</B><I>lon0/lat0/lonp/latp/scale</I> (Oblique Mercator -
point and pole)
<B>-Jq</B><I>lon0/scale</I> (Equidistant Cylindrical Projection
(Plate Carree))
<B>-Jt</B><I>lon0/lat0/scale</I> (TM - Transverse Mercator, set
origin)
<B>-Ju</B><I>zone/scale</I> (UTM - Universal Transverse Mercator)
<B>-Jy</B><I>lon0/lats/scale</I> (Basic Cylindrical Projection)
<B>AZIMUTHAL</B> <B>PROJECTIONS:</B>
<B>-Ja</B><I>lon0/lat0/scale</I> (Lambert).
<B>-Je</B><I>lon0/lat0/scale</I> (Equidistant).
<B>-Jf</B><I>lon0/lat0/horizon/scale</I> (Gnomonic).
<B>-Jg</B><I>lon0/lat0/scale</I> (Orthographic).
<B>-Js</B><I>lon0/lat0/</I>[<I>slat/</I>]<I>scale</I> (General Stereographic)
<B>CONIC</B> <B>PROJECTIONS:</B>
<B>-Jb</B><I>lon0/lat0/lat1/lat2/scale</I> (Albers)
<B>-Jd</B><I>lon0/lat0/lat1/lat2/scale</I> (Equidistant)
<B>-Jl</B><I>lon0/lat0/lat1/lat2/scale</I> (Lambert)
<B>MISCELLANEOUS</B> <B>PROJECTIONS:</B>
<B>-Jh</B><I>lon0/scale</I> (Hammer)
<B>-Ji</B><I>lon0/scale</I> (Sinusoidal)
<B>-Jk</B>[<B>f|s</B>]<I>lon0/scale</I> (Eckert IV (f) and VI (s))
<B>-Jn</B><I>lon0/scale</I> (Robinson)
<B>-Jr</B><I>lon0/scale</I> (Winkel Tripel)
<B>-Jv</B><I>lon0/scale</I> (Van der Grinten)
<B>-Jw</B><I>lon0/scale</I> (Mollweide)
<B>NON-GEOGRAPHICAL</B> <B>PROJECTIONS:</B>
<B>-Jp</B>[<B>a</B>]<I>scale</I>[<I>/origin</I>] (polar (theta,r) coordinates,
optional <B>a</B> for azimuths and offset theta [0])
<B>-Jx</B><I>x-scale</I>[<B>l|p</B><I>pow</I>][<I>/y-scale</I>[<B>l|p</B><I>pow</I>]] (Linear, log,
and power scaling)
More details can be found in the <B><A HREF="psbasemap.html">psbasemap</A></B> man
pages.
<B>-R</B> <I>west,</I> <I>east,</I> <I>south,</I> and <I>north</I> specify the Region of
interest. To specify boundaries in degrees and min
utes [and seconds], use the dd:mm[:ss] format.
Append <B>r</B> if lower left and upper right map coordi
nates are given instead of wesn.
</PRE>
<H2>OPTIONS</H2><PRE>
<B>-A</B> Force 1:1 scaling, i.e., output (or input, see <B>-I</B>)
data are in actual projected meters. To specify
other units, append <B>k</B> (km), <B>m</B> (mile),<B>n</B> (nautical
mile), <B>i</B> (inch), <B>c</B> (cm), or <B>p</B> (points). Without
<B>-A</B>, the output (or input, see <B>-I</B>) are in the units
specified by MEASURE_UNIT (but see <B>-M</B>).
<B>-D</B> Set the grid spacing for the new grid. Append <B>m</B> for
minutes, <B>c</B> for seconds.
<B>-E</B> Set the resolution for the new grid in dots pr
inch.
<B>-F</B> Toggle between pixel and gridline registration
[Default is same as input].
<B>-G</B> Specify the name of the output netCDF grd file.
<B>-I</B> Do the Inverse transformation, from rectangular to
geographical.
<B>-M</B> Append <B>c</B>, <B>i</B>, or <B>m</B> 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 <B>-A</B>.
<B>-N</B> Set the number of grid nodes in the new grid.
<B>-S</B> Set the search radius for the averaging procedure
[Default avoids aliasing].
<B>-V</B> Selects verbose mode, which will send progress
reports to stderr [Default runs "silently"].
</PRE>
<H2>EXAMPLES</H2><PRE>
To transform the geographical grid dbdb5.grd onto a pixel
Mercator grid at 300 dpi, run
grdproject dbdb5.grd <B>-R</B>20/50/12/25 <B>-Jm</B>0.25<B>i</B> <B>-E</B>300 <B>-F</B>
<B>-G</B>dbdb5_merc.grd
To inversely transform the file topo_tm.grd back onto a
geographical grid try
grdproject topo_tm.grd <B>-R</B>-80/-70/20/40 <B>-Jt</B>-75/1:500000 <B>-I</B>
<B>-D</B>5<B>m</B> <B>-V</B> <B>-G</B>topo.grd
This assumes, of course, that the coordinates in
topo_tm.grd were created with the same projection parame
ters.
To inversely transform the file topo_utm.grd (which is in
UTM meters) back onto a geographical grid we specify a
one-to-one mapping with meter as the measure unit:
grdproject topo_utm.grd <B>-R</B>203/205/60/65 <B>-Ju</B>5/1:1 <B>-I</B> <B>-Mm</B> <B>-V</B>
<B>-G</B>topo.grd
</PRE>
<H2>RESTRICTIONS</H2><PRE>
(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.
</PRE>
<H2>SEE ALSO</H2><PRE>
<I>gmt</I>(l), <I><A HREF="gmtdefaults.html">gmtdefaults</A></I>(l), <I><A HREF="mapproject.html">mapproject</A></I>(l)
</PRE>
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