Program: TraceDmp

Seismic Trace File Dump

Version: 1.9

• Introduction
• Running TraceDmp
• Menus and Controls
• Errors and Messages

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• Main Index

Introduction

TraceDmp enables seismic files, in SEG-Y or Lynx format, to be "dumped" as an on screen display. Dumps can be exported as column or comma delimted text files. All text header and trace header fields can be modified, by re-importing data from similar text files, or by using the spreadsheet editing option. For more information about Lynx and SEG-Y trace file formats, click here.

The main features of TraceDmp are:

• Reads SEG-Y and Lynx trace file formats
• Text header, binary header and trace header dumps
• Trace sample dumps
• Trace statistics
• Trace header field selector
• Spreadsheet editing, CSV file import/export
• Modify values in text, binary and trace headers
• Repair and analyse bad SEG-Y headers and trace headers
• Persistent dump configuration settings

Running TraceDmp

Seismic trace files can be opened in TraceDmp in a number of ways:

• Use the File-Open menu option or the toolbar     button.
• Drag a file from an Explorer window, and drop it on TraceDmp's main window.
• Use the seismic filepath as a command-line argument.

When a seismic trace file has been opened, TraceDmp's main window can show one of five types of dump

1. Text header for the file
2. Binary header for the file
3. Trace header values
4. Trace sample values
5. Trace sample statistics

The display for Text and Binary file headers is fixed, but the other three types of dump can be configured. The current dump configuration is saved in a file called TraceDmp.tdp in your Lynx custom directory (normally C:\User\\AppData\Roaming\LynxData\CUSTOM), so that when you restart TraceDmp, it will restore the configuration that was last used.

Menus and Controls

The main window has tabs to display the different dump types:

• Text File Header
  This is sometimes called the "EBCDIC header" or "C-Card header" for SEG-Y files.
  This option displays the standard layout for the current file's character header, which consists of 40 records of 80 bytes each and is ASCII characters for Lynx format and EBCDIC for SEG-Y format.
  The first five characters of each record are standard in both formats and should not be altered.

• Binary File Header
  This displays information from the binary header of the trace file, including the detected SEG-Y variant, and Lynx and Revison-1 specific information.

• Trace Headers
  This displays information from the trace headers. Select the fields which will appear in the trace header dump using the Dump-Configure Trace Headers  menu option.
  Select the range and increment of traces to display using the Dump-Set Trace Range  menu option.

• Trace Samples
  This displays the trace sample values. Select the sample window and display format using the Dump-Configure Trace Samples  menu option. Select the range and increment of traces to display using the Dump-Set Trace Range .

• Trace Statistics
  This shows statistics for the selected range of traces.
  Use the Dump-Configure Trace Statistics  menu option to determine which statistics to display.

The screen-shot below shows the Text Header dump of a SEG-Y file.

The screen-shot below shows the Trace Header dump of a SEG-Y file.

The main menu is laid out as follows:

• File

  • Open 
    Select a trace file to dump, from the standard open dialog.

  • Load from CSV 
    The text header, or the trace headers, for the current trace file can be modified by importing data from a CSV (comma separated value) file either exported by the Save Dump As option, or generated in a spreadsheet or text editor. It is advisable to make a backup copy of the trace file before using this option.

    The layout of the CSV file should be identical to the corresponding dump produced by the Save Dump As option above, using the following dump parameters:

    Orientation = Portrait
    Output format = CSV
    Headings and labels = YES

    When loading Trace Headers, the left column (column A) of the spreadsheet contains header identifiers, which should match exactly those of the relevant header fields. The first row of the spreadsheet (row 1) contains trace numbers to be replaced. The trace numbers in the spreadsheet should be within the range of trace numbers actually in the trace file. You can omit any trace numbers and fields for traces and trace header values which do not need to be altered.

    Note that trace headers can only be re-loaded in Portrait orientation (ie trace header fields across the page and trace numbers down the page). This is because of a limitation in Microsoft Excel of 256 columns maximum and possible problems with very long lines in comma delimited files.

  • Save Dump As 
    This enables the currently displayed dump to be saved as a text file. The Dump Format parameter page will be displayed, to determine the layout and format of the saved data.

    Orientation - select from:

    • Landscape - the dump is written with trace numbers increasing across the page and field names down the page
    • Portrait - the dump is written with trace numbers increasing down the page and field names across the page

    Output format - select from:

    • CSV - the data are written as a comma delimited file
    • Delimited - the data are written with columns delimted by the character specified below
    • Tabulated - the data are written in fixed width columns, specified by the column width parameter below.

    Delimiter character
    The character used to separate columns in each line of the output file, when the "delimited" output format is selected above.

    Column width
    The width of the columns, in characters, when the "tabulated" output format option is selected above.

    Headings and labels - select from:

    • Yes - row and column headings and labels will be included in the output file
    • No - row and column headings will not be included

    Confirm these options and then click OK to display a standard save file dialog to select the output dump file name.

• Dump
  • Configure Trace Headers 

    This menu option displays a dialogue box containing a standard Lynx dual list, enabling you to select the header fields you wish to display.

    

    Select the required fields from the left hand list and transfer them to the right hand list, which shows the fields to be dumped.
    Lynx trace files have well defined headers, based on the SEG-Y standard.
    

    The original SEG-Y standard defines header fields from byte 1 to 180 of each 240-byte trace header. SEG-Y Revision 1 defines additional header fields from byte 181 to 232. The SEG-Y Lynx Variant 3 format defines an additional field at byte 233 to hold the trace start time. These are all defined as integer values. To view non-standard fields, you can define custom header fields to display, as illustrated in the view above. Click the Add    button to display the SEG-Y Custom Trace Headers parameter page:

    Description - a description of the custom header field

    Start Byte - the starting byte number (1-based) of the header field

    Number Type - the binary format of the header field. Select from:

    • Integer-2 - 2-byte (16-bit) integer
    • Integer-4 - 4-byte (32-bit) integer
    • IEEE Float-4 - 4-byte (32-bit) IEEE floating point
    • IBM Float-4 - 4-byte (32-bit) IBM floating point

    Byte Order - select the byte ordering for the header field. The SEG-Y standard defines all header fields and sample values should be stored in big-endian (non-Intel) byte order, however this is not always the case for non-standard fields. Select from:

    • not Intel - big-endian byte order (most-significant byte first). This is the native byte format of IBM, Motorola and RISC chips.
    • Intel - little-endian byte order (least-significant byte first). This is the native format of Intel chips. Lynx trace file header field and sample values are stored in little-endian byte order.

    Display Decimals - the number of decimal places to display.

  • Configure Trace Samples 

    This menu option displays a PRMEDIT dialog with the following options:

    Sample Dump Mode - select how trace samples are displayed:

    • One trace per column - each trace is displayed in a separate column
    • Trace samples as a grid - samples are displayed as a matrix

    Trace number - This determines how trace numbers are written in the dump matrix. Select from:

    • None - do not write trace numbers
    • Rows - trace numbers are written at the beginning of every row of the dump
    • Traces - the trace number is written on a separate row at the beginning of the sample data for each trace

    Sample number - select from:

    • None - do not write sample numbers
    • Rows - the sample number for the forst sample in each row is written at the beginning of the row. Sample numbers within the rows are written at the head of each column

    Samples to dump - select from:

    • All - dump all samples in each trace
    • Range - dump a range of samples in each trace, specified by the Start and End times below.

    Start time msec - The time of the first sample to dump

    End time msec - The time of the last sample to dump

    Number of columns - Number columns of trace samples in the dump

    Sample display - select from:

    • Fixed - the sample values are displayed as fixed point decimal numbers, with the field width and number of decimal places specified below.
    • Scientific - the sample values are displayed in exponential format

    Field Width - Field width for the sample values, characters

    Display Decimals - Number of decimal places for the sample values

  • Configure Trace Statistics 

    This menu option displays a standard Lynx dual list dialog, allowing you to select the trace statistics to display. Select from:

    • Trace number - select the trace range and increment using the Set Trace Range menu option
    • Mean
    • Minimum sample value
    • Maximum sample value
    • Distance from 1st trace - this option uses the RX and RY trace header values to calculate the distance from the first trace dumped. Note that this is not the cumulative distance between each trace.

  • Set Trace Range  
    This shows the Select Trace Range parameter page, enabling the first and last trace for the dump and the trace increment to be set:

    Traces to dump - select from:

    • All - dump all traces in the file
    • Range - dump a range of traces specified below.

    First trace to dump
    The first trace in the file to dump

    Last trace to dump
    The last trace in the file to dump

    Trace increment
    The increment between traces in the dumped range

  • Edit as Spreadsheet  
    This is a quick way to modify the text header or the trace headers. When displaying these types of dump, this button exports the current display as a temporary CSV file to a spreadsheet (Microsoft Excel and LibreOffice/OpenOffice Calc are supported). You may alter the data, save the CSV file and return to TraceDmp by closing the spreadsheet, at which time the saved CSV file will used to modify the trace file, duplicating the action of Load from CSV.

    1. Choose the type of header to modifiy with the Text Header or Trace Headers menu options: you can only modifiy Text (EBCDIC) headers or trace headers with this option.
    2. If editing trace header fields, you should export and edit only the header fields you wish to modify: select the trace header fields to be modified using the Dump-Configure Trace Headers  menu option. Also ensure that you export the correct trace range and increment (you probably want to edit all traces).
    3. Click the Dump-Edit as Spreadsheet  option, and when the spreadsheet appears, modify the trace header (or C-Card value) cells to give the desired values. Do not change the row or column headings in the spreadsheet. You can, however, delete rows or columns which you do not wish to change.
    4. When you have completed your modifications, save the spreadsheet by overwriting the existing temporary file name.
    5. Close the spreadsheet to return to TraceDmp, which is suspended while the spreadsheet is running. The temporary file, in your LynxData\SCRATCH folder, will be destroyed by TraceDmp after the revised header values have been read back.

    When editing trace headers in this way, remember that most trace header fields in SEG-Y and Lynx format are integers - if you put decimal points in the corresponding spreadsheet fields, this will cause a conversion error when the CSV file is read back. Note also that 2-byte integer fields have a maximum range from -32767 to 32768.

  • Edit Binary header 
    This displays a parameter page which enables limited modification of the current file's binary header. Some of the entries on this page are "pseudo parameters", that are not actually stored in the binary header, but are derived from it. These parameters are greyed out in the binary header display, because changing them will cause the file to become unreadable by Lynx software.

    Client
    The Client name is obtained from the EBCDIC/ASCII text header of the trace file. (can change LYNX,SEG-Y)

    Profile Name
    The Profile Name is obtained from the EBCDIC/ASCII text header of the trace file. (can change LYNX,SEG-Y)

    Character format EBCDIC
    Indicates whether the text header of the file is ASCII (Lynx format) or EBCDIC (SEG-Y). Changing this parameter is not implemented

    Trace sample interval msec
    If you change this, the Time of first sample will remain the same and the Time of last sample and Time length will change accordingly (can change LYNX,SEG-Y)

    No.of samples per trace
    Changing this parameter is not implemented

    No. of bytes per sample
    Changing this parameter is not implemented

    Byte order Intel
    Changing this parameter is not implemented

    Samples are floating point
    Changing this parameter is not implemented

    Floating point format
    Changing this parameter is not implemented

    No. of traces in file
    (type long integer, limits 1 to 32000)
    This can be modified with caution for LYNX trace files: the file will subsequently only be read up to this trace number. The extra traces will not immediately be deleted from the disk file, but will be removed when the traces are rewritten.
    For SEG-Y files this value cannot be altered, as it is calculated from the file size, sample format and number of samples per trace.

    Time of first sample
    The start time of the traces (can change LYNX,SEG-Y)

    Time of last sample
    The end time of the traces will change automatically to reflect changes made in Time of first sample

    Time length
    Must be equal to the difference between Time of Last sample and Time of first sample, therefore cannot be changed

    Traces per CDP
    (can change LYNX)

    First CDP
    (can change LYNX)

    Last CDP
    (can change LYNX)

    CDP increment
    (can change LYNX)

    First Shotpoint
    This will not affect standard SEG-Y files, for which the First Shotpoint is not defined in the binary header. (can change LYNX)

    Shotpoint increment
    This will not affect standard SEG-Y files, for which the Shotpoint Increment is not defined in the binary header (can change LYNX)

    Trace spacing
    This will not affect standard SEG-Y files, for which the trace spacing is not defined in the binary header (can change LYNX)

  • Show Preserved Headers
    For Lynx Trace Files with preserved SEGY trace headers (LYNXP format), you can toggle between display of the Lynx trace headers and the 'shadow' SEGY headers from the original loaded SEGY format.

• Tools - this menu provides a set of tools for repairing corrupted SEG-Y and trace files

  • Binary Header Repair
    Rewrites the sample interval, bytes per sample and number of samples per trace in the binary file header.
    Use with care, because if any of these three parameters are incorrectly set, the trace file will be unreadable.
    The parameters determine the length in bytes of the individual seismic traces.

    On a SEG-Y tape, individual traces can be of different lengths, as determined by trace header bytes:

    115-116=Number of samples in this trace
    117-118=Sample interval microsec this trace

    In a SEG-Y disk file, to be readable by most current software, the traces should all be the same length, as determined by the binary header parameters, and the trace header values are ignored. If the traces are not all of the same length on the tape, you can still use the Lynx 3S SEGYLOAD utility to load the file in Lynx format and then convert it back to SEG-Y

    To find out what value to enter as the trace length, you can use a hexadecimal dump, such as Lynx TAPEFILE to examine the file structure. Alternatively, use the Estimate trace length tool.

    Binary Header Repair parameters

    Sample Interval microsecs
    The sample interval in microseconds for the trace samples.

    Bytes per sample
    Number of bytes per sample. This should be 4 for floating point, 2 for integer fixed point, or 1 for byte (Lynx format only)

    Samples per data trace
    This is equal to 1 + (trace length, msec)/(sampling interval, msec)

  • Text Header Repair
    Rewrite selected Comment cards in the file's text header. Cards 1 to 8 are rebuilt using the information entered below and the C-Card 6 is rebuilt with information from the binary header. The remaining cards 9 to 39 will be set with the correct C-Card number at the beginning and 77 blank characters. Card 40 will be written as C40 END EBCDIC.

    Text Header Repair parameters

    First C-Card to rebuild
    The C-Card number of the first C-Card to rebuild.

    Last C-Card to rebuild
    The C-Card number of the last C-Card to rebuild

    CLIENT
    Enter the name to go after CLIENT on C-Card 1, maximum 20 characters

    COMPANY
    Enter the name to go after COMPANY on C-Card 1, maximum 40 characters

    LINE
    Enter the name to go after LINE on C-Card 2, maximum 20 characters

    REEL NO.
    Enter the the REEL number, as appropriate

  • Trace Header Repair
    Reset bad bytes in trace headers.

    Sometimes trace headers will contain bad, non standard, or otherwise unreadable values, which may cause the whole trace file to be unreadable. This tool enables a chosen range of header bytes to be set to zero, over a chosen range of traces. You may need to reset some trace header values afterwards, but at least the trace file may be readable. Note that bytes 1..4 in each trace header will always be set to the sequence number of the trace within the file.

    Start byte
    The index of the first byte in the trace header to be set to zero. Trace header indices are 1-based.

    End byte
    The index of the last byte in the trace header to be set to zero. Trace header indices are 1-based.

    Start trace
    The first trace in the file, for which trace headers are to be modified

    End trace
    The last trace in the file, for which trace headers are to be modified

  • De-Spike
    Repair out-of-range trace sample values in the file, and zero invalid data at the end of the trace.

    De-spike trace parameters

    Clip minimum sample value to
    The minimum sample value (usually a negative number) allowed in a trace.

    Clip maximum sample value to
    The maximum positive sample value allowed in a trace.

    zero samples after end of trace
    YES - if the samples per trace calculated from the binary file header is greater than the samples per trace written in the trace header, the trace samples will be zeroed from that point.
    NO - do nothing.

  • Estimate Trace Length
    This option is only valid for SEG-Y files.
    Estimate the length in bytes for the traces in a SEG-Y trace file, so that the binary file header may be corrected in Binary header repair.

    The file is scanned and the results of scanning the text header and trace headers are shown on a panel in the main window.

  • Check SEGY Float

    This option is only valid for SEG-Y files containing 4-byte IBM floating point samples. Every sample on every trace is checked for valid IBM floating point data. Invalid samples having impossible combinations of bits are set to zero. These errors will normally manifest themselves as exponent overflows or denormalised mantissas and are usually the result of problems with SEGY tapes, or the field tapes from which they were created. A report can be generated which lists trace numbers for modified traces and the number of samples that were set to zero.

    Check SEGY Float parameters

    Write a list of repaired traces
    YES - writes a file listing the trace numbers for modified traces and the number of samples modified
    NO - do not write a listing

    File name for listing of modified traces Enter the name of the .csv file for the trace listing.

  • Tile All TRACEDMP Windows 
    TRACEDMP is often used to debug problems with specific files, and so it is often useful to display the results from two or more files side by side. This tiling option will arrange all your open TRACEDMP windows into vertical tiles on your current monitor.

Errors and Messages

Trace header field identifier not found
The trace header identifier in an input CSV file did not match the table in the program INI file.

Trace number out of range
The trace number in an input CSV file was outside the range of trace numbers in the current trace file.

CCard identifier is non numeric
The comment card identifier, column 1 in the input CSV file was non numeric

CCard number is out of range
The comment card identifier, column 1 in the input CSV file, was outside the range 1 to 40.

Cell A1 incorrect ID
When importing a CSV file, the top left cell of the spreadsheet did not contain the required identifier string. The error message indicates the actual and required ID.

Number of columns out of range
There were too many columns in the input CSV file

Error converting data field
The data in an input CSV file were non numeric, in a field which should be numeric, or contained a decimal point for an integer field.

Are you sure that you want to change the binary header?
Changing the binary header data can make the file unreadable. Are you sure that you want to proceed?

Trace read error
An I/O error occurred when reading from the trace file

Trace write error
An I/O error occurred when writing to the trace file

Wrong number of ini file keys
The number of key=value parameters in the program INI file [Lynx format] or [SEGY format] section was incorrect. This error indicates that the INI file has become corrupted.

Wrong input trace format for this operation
This operation will only work on input trace files having IBM floating point samples, e.g. SEGY