To open a Segy file or files click on the File menu item and select "Open", or click
on the file folder button on the menu toolbar.
Use the file browser that appears to select one or more SEGY files. The default file extensions are *.sgy and *.yd0, to browse other file types
set the "Files of type" drop-down list at the bottom of the browser to "all Files".
When selecting multiple files the files need not be related in any way by processor, format, vintage, etc.
In fact only the first file in the list is actually opened, the remaining file names are simply added to the Working Set list.
More files can be added to the list at any time. The files need not be from the same directories. There is no limit to the number of files that can be selected.
The name of the file that is opened will be displayed at the top of the window.
The binary header is inspected and the file specifications are calculated and displayed on the file status panel. Information displayed includes record length and sample rate in milliseconds, file size in megabytes, and number of traces in the file. There is no
limit to the size of a SEGY file.
A trace slider appears to the right of the file status panel. Use it to navigate through
the traces in trace and sample views.
The box to the right of the trace slider indicates the current (displayed) trace. This box can be manually edited to move to another trace. To use the slider click on the right or left arrow to move up or down one trace. Click to the right of the slider thumb to move up 10 traces or to the left of the thumb to move back 10. Use the mouse to slide the thumb left or right, the trace view will change each time the thumb moves.
Opening SEGYs in SegyList file
From the file browser select a SegyList file created by SegyTracker or SegyFinder.
See an example of a SegyList file below. SegyTool will add all the files
from the SegyList file to the Working Set list.
From the file browser select a text file that contains paths to SEGY files.
You can define blanks or commas as the field delimiters and set the field containing the paths.
All SEGYs contained in the file will be added to the Working Set List
Use the "View" menu item or the buttons on the view panel to select the file view.
The options are to view the EBCDIC header, binary header, trace header
, or data samples.
The default format, and range of possible formats, will change according to the view selected.
Use the "Format" menu item or the buttons on the format panel to select the format for displaying the file view.
The default formats are dependant upon the view. For the EBCDIC header the default is EBCDIC format and the option is for ASCII.
For the binary header view the default is 16 bit integer. For trace headers 32 bit integer, and for data samples IBM float if the
format code is 1, 16 bit integer if the format code is 3.
If the file is in SeisX format the format is set to SeisX and the format
will vary for individual byte locations depending on content.
For SeisX files generated prior to SeisX version 4.0 a format code of 1
denotes IEEE float and a 6 denotes IBM. Note that this is contrary to the CSEG standard. SeisX version 4.0 corrects this and uses a 1 for IBM float and a 6 for IEEE. SegyTool can convert betwen the two versions.
For binary, trace, and data samples the format options are:
The files selected by the user are kept in the working set.
This list of files can be traversed by clicking on the "Previous" and
" Next" buttons.These buttons iterate forward and backward through the list of selected files.
Each time a new file is opened the Display window is updated in the current format and view.
Any open dialogs such as the wiggle trace or graph displays are updated when a new file is selected.
To view or edit the working set list click on the "Working Set" button to display the Working Set Dialog as seen below.
This dialog is modeless, that is it can remain visible while you continue to work in the main window.
Each entry in the list contains:
The display window shows the current view in the current format.
Except for the EBCDIC header display, which is in plain text, the displays consist
of rows and columns of numbers. These numbers can represent 8, 16, or 32 bit integer or floating point values.
The number of rows and columns is determined by the format.
For the binary and trace header views the first column of each row is a byte counter and represents the starting byte number of the first column in the row.
In the samples display the first column is the sample number of the first column in each row.
Horizontal and vertical scroll-bars will appear when necessary.
For the trace header example above the format is 32 bit integer with each number representing the contents of 4 bytes.
There are 12 rows of 5 columns each where each row displays 20 bytes. The first column of the first row represents bytes 1 to 4, the next 5 to 8, the last 17 to 20.
The first column of the second row represents bytes 21 to 24 and so on up to the last column of the last row which represents bytes 237 to 240.
The last column of the first row, bytes 17-20, is the normal location of the shotpoint number.
The first column of the second row, bytes 21-24 usually holds the CDP number.
Bytes 81-84 and 85-88, the first two columns of the fifth row usually contain the X and Y coordinates.
Although the above example is viewed in 32 bit integer the trace header can be viewed in 8 or 16 bit integer, IBM or IEEE float to examine non standard trace headers.
The SeisX format displays individual columns in either 16 or 32 bit integer or IEEE float.
For example the shotpoint number, X and Y coordinates are displayed in IEEE float,
the CDP in 32 bit integer.
The SeisX format is selected automatically if the SeisX flag is set in the file but SeisX files can be viewed in any format.
In the above example of a binary header in 16 bit integer there are 20 rows of 10 columns with each column representing 2 bytes. Hence the first column is
bytes 1 to 2, then 3 to 4, 5 to 6, etc.
The sample rate in microseconds is written in the last two columns of the first row, bytes 17 to 18 and 19 to 20.
The first is the sample rate for the file, the second, not always present, is the sample rate recorded in the field.
The number of samples is writen in the first two columns of the second row, bytes 21-22 and 23 to 24, Again they represent the current and field values.
The sample format code is written in the third column of the second row, bytes 25 to 26.
The data samples view displays the data samples in any format.
In the above example the format is IBM float and each number represents 4 bytes. The layout is similar to the 32 bit integer trace header example above except each number contains 3 decimal places. Note that three decimal places is the precision displayed not necessarily the precision of the sample values.
Also note that the counter in the sample view indicates sample number not byte position as in the binary and trace header views.
The ebcdic header is displayed, and can be edited, as a text file. The only formats available are EBCDIC and ASCII. The correct format is the one that displays readable text.