SAC Command Reference Manual

SGF

SUMMARY

Controls the SAC Graphics File (SGF) device options.

SYNTAX

SGF {options}

where options are one or more of the following:

PREFIX text
NUMBER n
DIRECTORY CURRENT|pathname
SIZE NORMAL|FIXED v|SCALED v
OVERWRITE ON|OFF

INPUT

PREFIX text:Set the frame prefix to text (up to 24 characters long.)
NUMBER n:Set next frame number to n. If n is zero, then SAC searches the directory for SGFs and sets the frame number to the next value in the sequence.
DIRECTORY CURRENT:
 Put the SGFs in the current directory.
DIRECTORY pathname:
 Put the SGFs in the directory specified by pathname.
SIZE NORMAL:Produce a "normal" sized plot. A normal plot has a viewspace (the maximum plotting area) of 10 by 7.5 inches. Using default values, the viewport (the portion of the viewspace where the plot is drawn excluding axes and labels) itself is approximately 8 by 5 inches.
SIZE FIXED v:Produce a plot where the x viewport is v inches in length.
SIZE SCALED v:Produce a plot where the x viewport in inches is determined by multiplying v by the x world coordinate limits.
OVERWRITE ON|OFF:
 When it is turned on, the file numbers are not incremented. Each new file erases the previous file. This is especially useful with the PRINT option on most plot commands.

DEFAULT VALUES

SGF PREFIX F NUMBER 1 DIRECTORY CURRENT SIZE NORMAL

ALTERNATE NAMES: ID for PREFIX and FRAME for NUMBER.

DESCRIPTION

This command controls the frame naming conventions and final plot size for subsequent SAC Graphics Files. Each frame is stored in a separate file on disk. Each frame name is made up of four parts. In order they are:

pathname:The optional directory path name.
prefix:The frame prefix.
number:The three digit frame number.
.sgf:The suffix used to denote a SAC Graphics File.

By default the frame prefix is simply the letter "f", the frame number 1 and the files are put in the current directory (i.e. the first name is "f001.sgf".) You might want to changed the prefix to identify a set of files you wish to save. You can also specify a directory in which to store the files. This is very useful when you are changing directories while running SAC and want all the frame files in one place. The frame number is incremented each time a new frame is created. You can force the frame number to start at any given value. Starting at a number other than 1 might be useful if you are generating figures for a report over several days and wish to keep them in sequential order.

The folowing paragraph was writen more thaan 20 years ago, and so far as we can see the size options in the current SGFTOPS program provides a much cleaner way to change the overall size of the plot in an SGF file. Based on sample runs using the examples given below, the output SGF files all have the same physical size, and the aspect ratio of the plots are all the same. Hence, SGF SIZE simply introduces a scaling factor for the plots. We are leaving in the paragraph and examples because they seem to work, and there may be a feature we are missing.

There are several options that can be used to control the size of the plot. A normal plot has viewspace limits of 10 by 7.5 inches. Using the default viewport limits, this results in an approximately 8 by 5 inch plot. You can force the x viewport to a fixed length or you can have the x viewport be scaled to the world coordinate limits of your data. This size information is written to the SGF. It is the responsibility of program that converts a SGF to a specific output device to generate the coding to produce a correctly sized plot. SGFTOPS performs this conversion correctly although plots larger than a single page have to post-processed correctly.

EXAMPLES

To define a directory other than where you are attached and to reset to frame number to the next value in a sequence:

SAC> SGF DIRECTORY /MYDIR/SGFSTORE FRAME 0

To set the x viewport plot size to 3 inches (i.e., wallet size):

SAC> SGF SIZE FIXED 3.0

For create a poster size plot to put on your wall:

SAC> SGF SIZE FIXED 30.0

To set the x viewport plot size to be 1 inch long for every 10 seconds of seismic data:

SAC> SGF SIZE SCALED 0.1

In this last example, a plot where the data was 60 seconds in duration would be 6 inches long whereas a plot where the data was 600 seconds in duration would be 60 inches long and would require special post processing to produce.

SEE COMMANDS

BEGINDEVICES

LATEST REVISION

May 6, 2010 (Version 101.4)