PLOTSEGY V2.0 Changes to the Program PLOTSEGY V2.0 incorporates 4 major changes in function: 1) the ability to change the sample rate used or replace it if not found in the SEG-Y binary header. 2) the ability to scale the display of the data as either "trace normalized" or against a "relative amplitude" either calculated or entered by the user. 3) a trace increment parameter. 4) the ability to display 3 different trace header values. These last two changes allow PLOTSEGY to display unstacked SEG-Y data and label it appropriately. Show in figures 1 - 7 are the user-interface changes seen in PLOTSEGY V2.0. SAMPLE RATE After PLOTSEGY has opened the indicated input file and read the binary trace header information, the sample rate found in the binary header is displayed and the user has an opprotunity to change it if desired. The default value found in the binary header is displayed in square brackets ([sample rate]) and may be accepted by pressing . The user may enter a new value at the prompt, or "quit" or "exit". The sample rate accepted will be used in all subsequent calculations. SCALING - TRACE NORMALIZED Trace Normalized scaling will compute the average non-zero absolute sample value per trace and use that value to represent 1/2 a trace width when plotting that trace's samples. Each sample will be displayed relative to that average value for that trace. SCALING - RELATIVE AMPLITUDE Relative Amplitude scaling will take a user-defined set of traces from within the input file indicated and use the sample values of that set of data traces to compute the average non-zero absolute sample value representing 1/2 a trace width when plotting all samples within the data set. TRACE INCREMENT The TRACE INCREMENT parameter allows the user to increment the trace counter through the data. For unstacked data, this allows the user to display individual traces from each ensemble. For example, Baikal line 6 SEG-Y demultiplexed data has ensembles composed of 101 traces: 5 auxilary channels (traces 1 - 5) and 96 data channels (traces 6 - 101). Ensemble trace 6 is the 1st data trace per ensemble and represents the far trace. Ensemble trace 101 is the 96th data trace per ensemble and represents the near data trace. PLOTSEGY counts the physical traces in the file, where the 1st trace in the file is physical trace number 1. PLOTSEGY V2.0 will display ALL traces per ensemble, including the auxilliary traces, so they must be included in calculating a starting trace value. The PLOTSEGY V2.0 parameter 1st_trace_number is the number of the 1st physical trace in the file to display. If the data set is composed of 10 shot ensembles, the near trace for those 10 shots may be displayed by setting the PLOTSEGY V2.0 parameter 1st_trace_number to file trace 101 and the parameter trace_increment to 101. This will produce a display using physical traces 101, 202, 303, 404, 505, 606, 707, 808, 909 and 1010, which represent ensemble trace 101 for shots 1 through 10. A far trace display is possible by setting PLOTSEGY V2.0 parameter 1st_trace_number to physical trace 6 and the parameter trace_increment to 101. This will produce a display using physical traces 6, 107, 208, 309, 410, 511, 612, 713, 814, and 915, which represent ensemble trace 6 for shots 1 through 10. For stacked data, this allows the user to simulate the display more data per screen ("panel") then is physically possible. If the display monitor has VGA resolution, it is capable of displaying 550 traces per panel. If the SEG-Y data being displayed has 1100 traces in the data set, the "entire" line may be displayed by setting the PLOTSEGY V2.0 parameter traces_per_panel to 550 and the PLOTSEGY V2.0 parameter trace_increment to 2. This will decimate the data, displaying every other trace and simulates displaying 1100 traces per panel. TRACE HEADER DISPLAYS PLOTSEGY V2.0 annotates traces with the physical trace number within the file, labelled "File Trace", and one of 3 trace header values. The user may select header value CDP, ensemble trace number, or the original field record number (FFID) of that trace. ------------------------------------------------------------------------- FIGURES ------------------------------------------------------------------------- ---------------------------------------- SEGY INPUT FILE PARAMETERS ---------------------------------------- CURRENT WORKING DIRECTORY: D:\CPGMS\SEGY\P5 CURRENT FILE PATH: D:\CPGMS\SEGY\P5 enter new path, "exit", "-" to use the current working directory or press ENTER to use current file path: ..\DATA CURRENT FILE NAME: enter new name, "exit" or press ENTER to use current: 624-79.SGY 624-79.SGY currently has a sample rate of [ 4.000] msec. Enter a new sample rate if desired. Press to accept current value. sample rate [ 4.000]: FIGURE 1: PLOTSEGY V2.0 SEG-Y Input File Parameters Screen. ----------------------------- DISPLAY TRACE SCALING METHODS ----------------------------- NORMALIZED: PLOTSEGY will average the amplitudes within the current trace being plotted and uses that amplitude to represent 1/2 the trace width for the display of that trace. RELATIVE AMPLITUDE: The user selects a starting trace and the number of traces to use. PLOYSEGY will average the amplitudes found for all samples within that range of traces and uses that amplitude to represent 1/2 a trace width for the display of all traces in the data set. Trace scaling: (1) normalized (2) relative amplitude scaling [1]: 2 FIGURE 2: PLOTSEGY V2.0 Scaling Methods Screen. Press any key to accept the current relative amplitude to use for plotting. Enter a new relative amplitude value or press "C" to compute a new one. Current relative amplitude value [ 0.000]: C FIGURE 3: User has selected to scale the data using a relative amplitude to be computed ("C"). Traces in file 624-79.sgy: [493] The relative amplitude is computed by averaging the sample values over a range of traces given by a starting trace number and the number of traces to use. starting trace number: 200 number of traces to use: 10 FIGURE 4: User has requested the relative amplitude be computed from the average of the sample values found in traces 200 - 209. trace [200] average amplitude [134455664.000] trace [201] average amplitude [134324672.000] trace [202] average amplitude [134405600.000] trace [203] average amplitude [133956936.000] trace [204] average amplitude [133936984.000] trace [205] average amplitude [134326336.000] trace [206] average amplitude [134122296.000] trace [207] average amplitude [134137880.000] trace [208] average amplitude [134346800.000] trace [209] average amplitude [134024192.000] FIGURE 5: PLOTSEGY V2.0 display of calculating the average relative amplitude to be used. ---------------------------------------- INPUT FILE CHARACTERISTICS ---------------------------------------- FILE: 624-79.sgy sample rate: 4.000 msec number of samples: 1500 maximum time: 6000 msec bytes per trace: 6240 bytes in file: 3079920 traces in file: 493 scaling: RELATIVE AMPLITUDE scaling factor: 134203736.000 Press any key to continue... FIGURE 6: Input file characteristics displayed by PLOTSEGY V2.0 after computing a new relative amplitude. ---------------------------------------- TRACE PLOTTING TYPES ---------------------------------------- TRACE TYPES: (1) wiggle (2) variable area (3) both trace type [3]: ---------------------------------------- PLOT DISPLAY TIMES ---------------------------------------- minimum time [0]: maximum time [6000]: 1000 timing lines [1000]: 100 ---------------------------------------- TRACE PARAMETERS ---------------------------------------- trace gain [1.000]: 1.5 trace clipping [3]: 1 1st trace number [1]: Maximum horizontal resolution is 550 traces per panel. traces per panel [125]: trace annotation frequency [10]: trace increment [1]: Header value to display: (1) CDP Number (2) Ensemble Trace Numnber (3) Field File Number header value [1]: Figure 7: PLOTSEGY V2.0 Trace Information entry screen.