SEG-Y Trace Viewer

The Trace Viewer allows you to "try out" different possible formats and interpretations of the SEG-Y data before the entire file is processed. Use the Trace Viewer to investigate individual traces within the SEG-Y file and learn about the data types used in the file.

The Trace Viewer has three sections:

1. Settings for how the SEG-Y file should be interpreted.
2. Trace Headers for the specified trace. Trace header fields are defined as in the SEG-Y Rev. 1 standard, with first byte position shown. Each header value is interpreted as 4-byte signed, 2-byte signed, and 2-byte unsigned integers, and as 4-byte IBM and IEEE floating point values. Selecting “Allow non-standard offsets” will allow you to see trace headers “in-between” the defined positions that are not part of the SEG-Y standard but are sometimes used.
3. A wiggle-plot of the current trace, based on the specified byte order and the Trace data format in the first section. Trace data format is independent of trace header formats.

SEG-Y Trace Viewer dialog options

Allow non-standard offsets	You can view the trace-header values in standard and non-standard trace-header locations using any of the available data formats. Offsets (Byte#) are now listed from 1 to 239, as all the intermediate /odd offsets between the standard trace header locations are available. No Select this option to view the trace-header values in standard trace-header location locations. Yes Select this option to view the trace-header values in standard and non-standard trace-header locations.
Byte order	Specify the byte order you wish to be used to interpret the entire file: "Big endian" or "Little endian." The default is "Big endian." If this setting is incorrect, the remaining fields in this dialog will contain nonsensical values.
Trace data format	Select the trace data format from the drop-down list. The selection of the data type will affect the appearance of the trace below. An incorrect number of bytes in the selected format may cause subsequent traces to appear truncated, or not appear at all.
Number of samples	Specify the number of samples. An incorrect number of samples will cause the trace plot to appear truncated, have gaps in it, and/or subsequent trace headers and traces to be corrupted.
Current trace	You may enter a specific value to view that trace or move the slider to scroll through the file and see many traces. The trace number is sequential for the file.

The plot section at the bottom of the dialog displays the currently selected trace based on the trace data format selected:

The preview helps to quickly validate the configuration selections, i.e., sample data format, byte order, number of samples. You may choose between the available trace formats and visually determine which one is the correct format. Furthermore, viewing several traces provides visual clues if anything is wrong: use the upper section selection tools (up/down arrow buttons and horizontal slider) to scroll through the traces in your SEG-Y file.
To see the entire trace, use the horizontal slider in the plot section. The Min and Max values will change as you scroll across and the trace range increases and decreases. Note that a "zeroed" part (usually the top of the trace) will show as a centred, straight line in the trace display.

Application Notes

The SEG-Y Standards (Rev. 0 & 1) are very specific about the appropriate locations for information and the data formats used to store them. However, the specifications are not rigidly followed, and files are written using many poorly-documented variations. For instance, the standard states that all trace headers should be written as 2- or 4-byte integer values, but some fields may be stored as floating point values. This wizard and the Trace Viewer are designed to follow the standard but also to allow flexibility in how a SEG-Y file is read should exceptions be encountered.