mbgrdtiff
Section:  MB-System 5.0  (1)
Updated:  5 February 2015 
Index


 
NAME

mbgrdtiff - GMT plug-in module for generating a geographically
located GeoTIFF image from a GMT grid file.

 
VERSION

Version 5.0

 
SYNOPSIS

gmt mbgrdtiff -Ccptfile -Igrdfile
-Otiff_file [-H -Kintensfile -V -W]

 
DESCRIPTION

mbgrdtiff is a plug-in module to generate a Geographically located
GeoTiff image from a GMT grid file using GMT (Generic Mapping Tools).
Like mbcontour and mbswath, mbgrdtiff
is fully compatible with the GMT package version 5.
A GeoTIFF image file includes location, projection and scaling information.
The image generation used by mbgrdtiff is identical to
that of the Postscript-producing GMT program
grdimage. In particular, the color map is applied from
a GMT CPT file, and shading overlay grids may be applied.
The image is 8 bits
per pixel if the color map is a grayscale, and 24 bits
per pixel otherwise. In order to automatically generate a
reasonable image of a grid, use the macro mbm_grdtiff.
The program mbgrdtiff recognizes the coordinate system
used by mbgrid or mbmosaic to generate a grid file, and
then embeds the projection and grid bounds information into the TIFF
image in accordance with the GeoTIFF standard. A number of GIS software
packages recognize the georeferencing information in GeoTIFF images.
In particular, images generated by mbgrdtiff from grids created
using mbgrid or mbmosaic can be loaded into the
GRASS, ArcInfo, ArcView, and ArcGIS GIS packages as geographically located
coverages.  The mbgrid and mbmosaic manual pages each contain
an appendix with a complete list of the projected coordinate systems that
may used in grid generation. Some software packages (e.g. Winfrog) do not
recognize the embedded coordinate system information, and install require
a parallel "world" file to specify the bounds and resolution. The -W
option causes a world file to be generated with a ".tfw" suffix.

In order for GMT to successfully execute mbgrdtiff, the
location of the shared library libmbgmt containing this module must be known to GMT.
This can be accomplished by either setting the GMT_CUSTOM_LIBS parameter
in the file gmt.conf that is part of the GMT installation, by setting
this parameter in the file gmt.conf in the user's home directory, or by
using the GMT module gmtset to modify this parameter in the
current working directory. If, for instance, the libmbgmt shared library
has been installed in the file /usr/lib/libmbgmt.dylib, then the
GMT_CUSTOM_LIBS parameter in a gmt.conf file can be set to:

        GMT_CUSTOM_LIBS = /usr/lib/libmbgmt.dylib

 
AUTHORSHIP

David W. Caress (caress@mbari.org)




  Monterey Bay Aquarium Research Institute



Dale N. Chayes (dale@ldeo.columbia.edu)




  Lamont-Doherty Earth Observatory

 
OPTIONS


-C


Sets the color palette (CPT) file which controls the color of the plot.
See documentation of the GMT package for a complete description
of cpt files. If the R, G, and B values in the CPT file are all
equal for each data level (i.e. R=G=B), the the output TIFF
image will be 8 bits per pixel. Otherwise, the output TIFF image
will be 24 bits per pixel.
-H


This "help" flag cause the program to print out a description
of its operation and then exit immediately.
-I


grdfile



The first invocation of the -Igrdfile option sets
the name of the gridded data file to be plotted.
The data must be in a form acceptable to GMT version 3
programs (see the GMT Cookbook & Technical Reference).
-I


intensity_file



The second invocation of the -Igrdfile option sets
the name of a gridded data file containing
intensity values to be used for shading the map.
Alternatively, grdfile may be a list of grid files
(one filename on each line) to be used together. If a
list of files is supplied, the intensity files must
conform in order to the list of data grid files they will shade.
-O


root



Sets the root used to construct the filename of the output shellscript
(root.cmd) and names of files created when the shellscript is
run.  Normally the
name of the input grid file or grid file list is
used as the root.
-V


Selects verbose mode [Default runs "silently"].
-W


The -W option causes a "world" file to be generated parallel to the
GeoTiff image with a ".tfw" suffix. Some software packages (e.g. Winfrog) do
not recognize the coordinate information embedded in the GeoTiff file, and
look for a world file.

 
EXAMPLES

Suppose we have obtained two GRD files called PunaA_bath.grd
and PunaA_ss.grd, both with dimensions
1162 x 1068. The file PunaA_bath.grd contains seafloor
topography (depth values are negative, ranging
from -5035 m to -1619 m), and the file PunaA_ss.grd
contains a sidescan mosaic (reflectivity values
ranging from 0 to 128 dB). In order to generate
a 24 bit color TIFF image of the seafloor topography, we use:




        gmt mbgrdtiff -I PunaA_bath.grd                 -O PunaA_bath.tif               -C bath.cpt -V




where the color is controlled by a GMT cpt file bath.cpt
containing:




        -5250  37  57 175 -4875  40 127 251


        -4875  40 127 251 -4500  50 190 255


        -4500  50 190 255 -4125 106 235 255


        -4125 106 235 255 -3750 138 236 174


        -3750 138 236 174 -3375 205 255 162


        -3375 205 255 162 -3000 240 236 121


        -3000 240 236 121 -2625 255 189  87


        -2625 255 189  87 -2250 255 161  68


        -2250 255 161  68 -1875 255 186 133


        -1875 255 186 133 -1500 255 255 255




In order to generate
an 8 bit grayscale TIFF image of the sidescan mosaic, we use:




        gmt mbgrdtiff -I PunaA_ss.grd           -O PunaA_ss.tif                 -C ss.cpt -V




where the grayscale is controlled by a GMT cpt file ss.cpt
containing:




         0.00   0   0   0   16.50  26  26  26


        16.50  26  26  26   22.87  51  51  51


        22.87  51  51  51   27.00  77  77  77


        27.00  77  77  77   30.00 102 102 102


        30.00 102 102 102   32.25 128 128 128


        32.25 128 128 128   34.25 153 153 153


        34.25 153 153 153   36.25 179 179 179


        36.25 179 179 179   38.50 204 204 204


        38.50 204 204 204   41.23 230 230 230


        41.23 230 230 230  128.00 255 255 255




Here greater reflectivity amplitudes are represented by
light grayscales.

 
SEE ALSO

mbsystem(1), mbm_grdplot(1), mbgrid(1), mbmosaic(1),
mbm_grid(1), mbm_grdtiff(1), gmt(1), grdimage(1)

 
BUGS

Let us know.



 
Index

NAME

VERSION

SYNOPSIS

DESCRIPTION

AUTHORSHIP

OPTIONS

EXAMPLES

SEE ALSO

BUGS

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