This example continues the San Diego Trough example by creating plot files for display in Fledermaus.
Getting the ASCII NAV into SEG-YThe USGS *.sgy data do not contain the navigation. The navigation is in a separate ASCII file where the lat/long are given for the SEG-Y "energy source number" or ESPN.
All the scripts.
Print the SEG-Y rp numbers (word 6) and energy source numbers (word 5)Word 5 is the SEG-Y ESPN, word 6 is the RP number Save this list in a file named *.prt. e.g. mkprt WSD81-711__26481 > WSD81-711__26481.prt where WSD81-711__26481.prt is: **** 0 ERRORS IN THIS JOB **** 1.0000 4966.0 2.0000 4966.0 3.0000 4965.0 4.0000 4965.0 5.0000 4964.0 6.0000 4964.0 7.0000 4963.0 8.0000 4963.0 9.0000 4962.0 10.000 4962.0 ****** Note that there are two traces for each ESPN. *******
Break the USGS nav file into lines.ls -l w-31-81-sc.051-nav.txt -rw-r--r-- 1 henkart wheel 9342776 Oct 31 14:04 w-31-81-sc.051-nav.txt That's a big ASCII file, so I used a text editor and made a nav file for each seismic line. e.g. 711.nav If there are multiple SEG-Y files for the seismic line, make sure the ASCII nav file contains the energy source numbers of the SEG-Y file. ****** Make sure the nav file has ALL the ESPNs by looking at the *.prt file. ***
Create a nav file formated for sioseis.Create a sioseis formated nav file. e.g. tosio.perl 711.nav > 711.sionav 711.sionav starts with: 0 0 0 0 0 33.46222 0 -117.83770 0 25 0 0 0 0 0 33.46203 0 -117.83756 0 26 0 0 0 0 0 33.46184 0 -117.83741 0 27 0 0 0 0 0 33.46165 0 -117.83727 0 28 0 0 0 0 0 33.46146 0 -117.83712 0 29 0 0 0 0 0 33.46127 0 -117.83698 0 30 0 0 0 0 0 33.46108 0 -117.83684 0 31 0 0 0 0 0 33.46089 0 -117.83670 0 32 The right-most column is the ESPN. ****** Determine what portion of the SEG-Y data you want to process by examining *.sionav and *.prt. Some SEG-Y file are very big and will create very big plot files. e.g. I choose to limit the data to be between 32.6N and 32.9N
Create a new SEG-Y file with the navigation in it. GEOM TYPE 18Process GEOM type 18 inserts the nav from a sioseis formatted ASCII file using the time of shot or the shot number or the rp number. Sioseis doesn't use the energy source number. Process header is used to save the original rp number (word 6) into segy word 1, then replace the rp number with the energy source number (l1 = l6 l6 = l5). Limit the data to be processed by using diskin parameters FNO and LNO. Create a separate script for each seismic line. **** WARNING **** Datasets "shot backwards" (the nav and segy data are in opposite directions) cause type 18 geometry to search the ASCII file for each new nav point.
Create an XY file for Fledermaus' mkvcurtain command.Recall that the navigation is duplicated on alternate shots, so only only every other navigation point is printed from the segy file. e.g. mkxy 711
Create a plot for FledermausCreate a grayscale plot - a traditional red/blue plot will cause visual confusion when the plot orientation in Fledermaus changes (rotates). Use ImageMagick's -transparent white option to signal that the white of the plot can be removed and made transparent. The direction of the seismic plot doesn't matter since it will be geo-referenced in Fledermaus. Create a TIFF file since Fledermaus doesn't allow PNG. Flip the plot (left to right) because SIOSEIS' plot origin (0,0) is the top right (plotters) and images are top left (screens). Resize the image to be 25% of the original. e.g. mkgplt 711
Create a Fledermaus SD fileFledermaus' "Import vertical images" assumes that the seismic data were shot in a straight line. Using progarm FMCommand, under pull down "Command & Control", in the command box, type: mkvcurtain -in 711.tif -xy 711.xy -out 711.sd -zrange -5000 0 The .sd files may be loaded into Fledermaus under the "file" pulldown menus and the "load data object". Z range may be changed under the Fledermaus pulldown menu "controls" and then "geo-referencing". Save everything as a scene file.