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|Author||Topic: What is the format of geometry files for 2d_land?||877 Views|
20 December 2018 at 5:38am
I am a student at University of leeds and I am using Claritas as a part of my final year project. I do not have any SPS files so I need to create them from the beginning. I know that I need to create two main text files which contain the source and receiver information then convert them to SPS files. Unfortunately, I have a problem with the correct formate of the text files.
My main aim of the geometry is to convert the numbers of Geophons into distances. for example, first Geophone is at distance 0m and second geophone at distance 3m and so on.
my questions are:
Do I need to have SPS files in order to add the distance or there is another way?
What is the correct format for the text files before converting to SPS files?
20 December 2018 at 1:41pm
The GLOBE Claritas geometry application can read in a variety of input file formats:
• SPS – three files: shot (*.s), receiver (*.r) and relational (*.x)
• *.sur / *.obl – *.sur land shot-point and receiver point positions, *.obl land shot record positions and channel configuration
• *.sht or *.str / *.txy – *.sht marine shot-point or navigation points, *.str marine streamer definitions, *.txy individual trace co-ordinate positions
Details on the required format of these files can be found in the ‘geometry : survey data definition and manipulation’ section of the manual (‘Browse manuals’ button on the ‘Help’ tab of the launcher):
• The survey file (*.sur)
• The observer’s log file (*.obl and *.obs)
• The marine shot file (*.sht)
• The marine streamer file (*.str)
• The trace coordinate file (*.txy)
The ascobl and ascsur utilies can be used to convert ASCII files to XPS or *.obl files, and from ASCII files to SPS S/R files, or *.sur files. These utilies can be accessed via the ‘Create XPS or .obl’ and ‘Create SPS/RPS or .sur’ buttons on the ‘Geometry’ tab of the launcher. And more details on how these utilities work can be found in the ‘Utilities : Miscellaneous small programmes ‘ – ‘Survey geometry-related utilities’ section of the manual.
If needed Excel (or some other spreadsheet editor) could be used to create text files containing the geometry information for the data.
The shot SPS file should have columns with values for shot-peg, easting, northing, elevation. Similarly the receiver SPS file should have values for rec-peg, easting, northing, elevation. while the relational SPS file should contain columns with the shot-ID, shot-peg, first channel, last channel, channel increment, first rec-peg, last rec-peg. There are example SPS files included with our 2D land tutorial – please see attachments.
The TXTHDR and ADDHDR modules can both be used to add data to specified headers. However, the ADDHDR module requires a specific format input file, while TXTHDR can cope with a wide range of input ascii files - as long as they have some sort of regular column format.
20 December 2018 at 2:08pm Last edited: 20 December 2018 2:09pm
so, what I understood is that I firstly need to create ASCll files that contains the geometry data with the correct formate for SPS files ( which is explained under geometry : survey data definition and manipulation section of the manual) then I need to convert them into SPS files using ascobl and ascsur utilies.
Is that correct???
20 December 2018 at 3:01pm
To create SPS files from ascii files use the ascobl and ascsur utilities. The ascii files should store the geometry info in a regular column format, the order of the columns doesn't matter. The ascii files for the shot SPS and receiver SPS files should have columns with values for peg number, easting, northing, and elevation. While the ascii file for the relational SPS file should contain columns with the shot-ID, shot-peg, first channel, number of channels, first rec-peg. There are examples in the ‘Utilities : Miscellaneous small programmes ‘ – ‘Survey geometry-related utilities’ section of the manual -> 'ascobl : Conversion from ASCII files to XPS or *.obl files' and 'ascsur : Conversion from ASCII files to SPS S/R files, or *.sur files'.
Have a quick look at the attached example SPS files, what is stored in each column is listed in the file header lines (those starting with an H) just above the geometry data (lines starting with a S, R, or X). These could be used as a template for creating the correct format SPS files from scratch, rather than using ascobl and ascsur. The header lines are not required so could always be deleted.
When editing files such as SPS in xedt (GLOBE Claritas text editor) Ctrl-P can be used to position the columns correctly - it will shift the remaining lines of the file (i.e. lines below where the cursor is positioned) out by one character position from the cursor location (Ctrl-Shift-P does the opposite of this - pulls columns in, deletes a character position)
20 December 2018 at 3:31pm
thank you I totally understood, I noticed in the headers of the SPS files that you used (map grid northing and map grid easting). are they the same as the usual northing and easting value because they seem quite different ??. did you converted them to another values??
20 December 2018 at 4:06pm
Yes, sorry, the easting and northing values have had a specified value subtracted from them all - I believe 2630000 from the eastings and 6226000 from the northings. This would have been done when they were created in the ascsur utility.
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