Gmt tools

The standard parallel is typically one of these but can be any value :. Specify one of:. Use upper-case A B C to remove enforcement of a northern hemisphere pole. Several optional modifiers control the perspective:. If tilt is negative, then the viewpoint is centered on the horizon [0]. Alternatively append R if giving the distance of the viewer from the center of the Earth in Earth radii, or r if giving the distance from the center of the Earth in kilometers. Finally, give altitude as g to compute and use the altitude for a geosynchronous orbit.

The following modifiers are supported by -Jp P :. Use negative scale s to reverse the direction of an axis e. Set height or width to 0 to have it recomputed based on the implied scale of the other axis. Optionally, append to x-scale y-scale , width or height one of the following:. When -J is used without any further arguments, or just with the projection type, the arguments of the last used -J , or the last used -J with that projection type, will be used.

Set z-axis scaling; same syntax as -Jx. It is, however, beyond the scope of this manual to document the PROJ syntax that is the syntax of the proj and cs2cs programs so users are referred to PROJ Applications for the details.

The usage of PROJ follows very closely the syntax of proj and cs2cs. The projection parameters are encapsulated under the -J option. For mapproject and grdproject we can go directly from the referencing system A to B without the intermediate step of converting to geographic coordinates.

A much awaited bonus is also that we now do not need to set -R to do point coordinate conversions. While for point and grid conversions done by mapproject and grdproject we can use all PROJ projections , the situations is, however, rather more limited for mapping purposes. Specify the region of interest. The -R option defines the map region or data domain of interest. It may be specified in one of several ways options 1 and 3 are shown in panels a and b respectively of the Figure Map region :.

This is the standard way to specify Cartesian data domains and geographic regions when using map projections where meridians and parallels are rectilinear, where xmin , xmax , ymin , and ymax refer to the data limits. The coordinates are relative to the standard longitude and latitude indicated in the projection -J. This form is useful for map projections that are oblique, making meridians and parallels poor choices for map boundaries.

This form guarantees a rectangular map even though lines of equal longitude and latitude are not straight lines. This will copy the domain settings found for the grid in specified file. Note that depending on the nature of the calling module, this mechanism will also set grid spacing and possibly the grid registration see Grid registration: The -r option. This indirectly supplies the region by consulting the DCW Digital Chart of the World database and derives the bounding regions for one or more countries given by the codes.

Simply append one or more comma-separated countries using the two-character ISO alpha-2 convention. To select a state within a country if available , append.

TX for Texas. The following modifiers can be appended:. This method can be used when creating grids. This is not used for -p without -Jz , in which case a perspective view of the place is plotted with no third dimension. Under modern mode, and for plotting modules only, you can automatically determine the region from the data used. You can either get the exact area using -Re [Default if no -R is given] or a slightly larger area sensibly rounded outwards to the next multiple of increments that depend on the data range using -Ra.

In case of perspective view -p , a z-range zmin , zmax can be appended to indicate the third dimension. This needs to be done only when using the -Jz option, not when using only the -p option. In the latter case a perspective view of the plane is plotted, with no third dimension. Draw GMT time stamp logo on plot.

The -U option draws the GMT system time stamp on the plot. The following modifiers are supported:. The time string will be in the locale set by the environment variable TZ generally local time. Select verbosity level [ w ]. The -V option controls the verbosity mode, which determines which messages are sent to standard error. Choose among 7 levels of verbosity; each level adds more messages:. Shift plot origin.

The -X and -Y options shift the plot origin relative to the current origin by xshift , yshift. Optionally, append the length unit c , i , or p. Subsequent overlays will be co-registered with the previous plot unless the origin is shifted using these options. The following modifiers are supported [default is r ]:. Prepend c to center the plot on the center of the paper optionally add a shift.

When -X or -Y are used without any further arguments, the values from the last use of that option in a previous GMT command will be used. Note that -X and -Y can also access the previous plot bounding box dimensions w and h and construct offsets that involves them.

Note : the previous plot bounding box refers to the last object plotted, which may be an image, logo, legend, colorbar, etc. GMT relies on external tools to translate geospatial files such as shapefiles into a format we can read. For this to be useful we need a mechanism to associate certain metadata values with required input and output columns expected by GMT programs.

The given aspatial field thus replaces any other value already set. Note : If no aspatial attributes are needed then the -a option is not needed — GMT will still process and read such data files.

You can also associate aspatial fields with other settings such as labels, fill colors, pens, and values for looking-up colors by letting the col value be one of D for distance , G for fill , I for ID , L for label , T for text , W for pen , or Z for value. This works analogously to how standard multi-segment files can pass such options via its segment headers See the cookbook chapter GMT File Formats. As for input, you can also use the special col entries of D for distance , G for fill , I for ID , L for label , T for text , W for pen , or Z for value to have values stored as options in segment headers be used as the source for the named aspatial field.

The type will be set automatically for these special col entries. Select native binary record format for primary table input. The record is one or more groups with format [ ncols ][ type ][ w ], where ncols is the number of consecutive data columns of given type and type must be one of:. Force byte-swapping of a group by appending w at the end of the group. For records with mixed types, append additional comma-separated groups no space between groups.

The cumulative number of ncols may exceed the columns actually needed by the program. If ncols is not specified we assume that type applies to all columns and that ncols is implied by the expectation of the program.

When using native binary data the user must be aware of the fact that GMT has no way of determining the actual number of columns in the file. Native binary files may have a header section, where the -h option can be used to skip the first n bytes. If the input file is netCDF, no -b is needed; simply append? Here is an example that writes a binary file and reads it back with the first column 4 byte float, the second column 8 byte int, and the third column 8 byte double.

Select native binary format for table output. Tell us what you like and we'll send you special offers for things that interest you! Signup for email deals Exclusive savings for subscribers. Carbide Inserts Carbide Inserts. You're now signed up to receive emails with the latest sales events, exclusive offers, and special announcements from glacern.

We want to keep in touch, but only if it's helpful to you! Tell us what you like and we'll send you special offers for things that interest you! Signup for email deals Exclusive savings for subscribers. Got questions? Check out the GMT interfaces! Whether Cartesian, geographic, or time-series, GMT can process your data. GMT enables you to explore new ways to analyze data and to build custom displays for drafts, publications, or final presentations.