Equivalent Layer corrections (T36)
Contents
1. Specifying input and output files Library Help Top To use Equivalent Layer you will need to specify some or all of the following files Usedin Used in stage 2 stage 3 Required YES YES File Required Optional Line dataset Z field or grid dataset for correction Platform height line dataset field or grid dataset Optional YES YES Ground clearance line dataset field not Optional YES YES available for grid datasets process Required YES YES Required YES Wiener kernel Layer grid output YES YES Layer grid input Required Corrected line dataset Z field or grid dataset Required output Choose the options as required from the File menu Options Help Load Field as Line Dataset Load Field as Grid Dataset Load Platform Height as Line Dataset Load Ground Clearance as Line Dataset Load Platform Height as Grid Dataset specify Constant Platform Height Load Wiener Kernel specify Output Layer Grid Load Layer Grid For Recalculation save Recalculated Values Load Options save Options In each case INTREPID displays an Open or Save As dialog box Use the directory and file selector to locate the file you require See Specifying input and output files in Introduction to INTREPID R02 for information about specifying files 1 Line dataset note INTREPID will need to obtain information from the dataset aliases The dataset must have aliases identifying app2. 101 xDimK 15 yDimK 15 Mode Magnetic Parameters End Process End Equivalent Layer task specification files will be available soon 2012 Intrepid Geophysics 4 Back gt
3. job file in order to repeat a similar task later or for some other reason use Save Options from the File menu See Specifying input and output files for detailed instructions 11 Exit from the Wiener kernels tool Choose Quit from the File menu Stage 2 Calculating the equivalent layer grid 12 Launch the Equivalent Layer tool Choose Equivalent Layer from the Filtering menu in the Project Manager or use the command slayer exe INTREPID displays the Equivalent Layer window Intrepid slayer Tool 3 2 File Options Help Apply J Extrapolate smoothly into edge O Reflect data into edges O Taper to zero at edges O Detrend degree 2 O Detrend degree 3 13 If you have previously prepared file specifications and parameter settings for stage 2 or stages 2 and 3 of the Equivalent Layer process load the corresponding task specification file using Load Options from the File menu See Specifying input and output files for detailed instructions 14 If all of the specifications are correct in this file go to step 24 If you wish to modify any settings carry out the following steps as required Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 5 Library Help Top Library Help Top 15 16 17 18 19 q Back gt Specify the grid dataset or line dataset Z field you wish to process using the Equivalent Layer tool Use Load Field as
4. inclination to be used when recalculating 90 00000 22 Specify the options as required and choose OK Number of Iterations Use this to specify the number of times for INTREPID to apply the Wiener kernel to the grid A larger number of iterations will produce a smoother result Smoothing With each iteration of the Equivalent Layer process INTREPID performs a moving average smoothing process Use the Smoothing parameter to specify the starting smoothing factor INTREPID decreases this factor with each iteration We recommend a value of 11 for this parameter Field inclination to be used when recalculating Use this to specify the desired field inclination for the results of the Equivalent Layer process If you are using the process to perform reduction to the pole set the desired inclination to 90 If you are not performing reduction to the pole set the desired inclination to the correct Earth s core magnetic field inclination for the survey This will be the same setting that you specified for Inducing field inclination degrees in the Wiener Kernels tool above 23 Specify the output layer grid using Specify Output Layer Grid from the File menu See Specifying input and output files for detailed instructions 24 When you are satisfied that all input output and parameter specifications are as required choose Apply 25 If you wish to record the specifications for stage 2 of the process in a job file in order to repeat a
5. process turn on the check box es corresponding to the results you wish to save Save Auto Correlation Matrix Use this to save the auto correlation matrix used in the process INTREPID will save it as a text file called autocorr obs Save Cross Correlation Matrix Use this to save the cross correlation matrix used in the process INTREPID will save it as a text file called croscorr obs 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 4 Library Help Top 4 Back gt Save Filtered Known Input Use this to save the Filtered Known Input a matrix of size equal to the number of cells along side of calculated grid See Step 6 above INTREPID saves the matrix as a text file called filt obs If the points above the prism are close in value to the Susceptibility See step 3 above and the points not over the prism are close to 0 this indicates that the filter response will be close to your desired results 8 Specify a file name for the Wiener kernel you have specified Choose Save As from the File menu and specify a name for the Wiener kernel Save the kernel in the project directory the same directory as the input grid dataset or the input line dataset marker DIR file INTREPID will automatically add the extension ker to the file name 9 When you are satisfied that all specifications are as required choose Apply 10 If you wish to record the specifications for this process in a
6. similar task later or for some other reason use Save Options from the File menu See Specifying input and output files for detailed instructions Stage 3 Calculating the corrected grid or Z field Recalculation 26 If you loaded a task specification file in step 13 above and all of the specifications are correct in this file for stage 3 of the process go to step 30 If you wish to modify any settings carry out the following steps as required 27 If you have previously prepared file specifications and parameter settings for stage 3 of the Equivalent Layer process load the corresponding task specification file using Load Options from the File menu See Specifying input and output files for detailed instructions 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 7 Library Help Top lt 4 Back gt 28 Specify the layer grid that you created in stage 2 Specified in step 23 using Load Layer Grid for Recalculation from the File menu See Specifying input and output files for detailed instructions 29 Specify the Z field or grid for the corrected values resulting from the Equivalent Layer process Use Save Recalculated Values from the File menu See Specifying input and output files for detailed instructions 30 When you are satisfied that all input output and parameter specifications are as required choose Recalculate 31 If you wish to record the specifications
7. INTREPID User Manual Equivalent Layer corrections T36 1 Library Help Top 4 Back gt Equivalent Layer corrections T36 The Equivalent Layer tool now in beta release and supplied with INTREPID can perform e Height corrections for a survey smoothing the undulations in the flight path and e Reduction to the pole at any latitude Before using the Equivalent Layer tool you must use the Wiener Kernels tool to calculate a Wiener convolution kernel for the process you are carrying out Stages in the Equivalent Layer process The Equivalent Layer tool can be used to correct a line dataset Z field or a grid dataset There are three stages in the process 1 Using the Wiener Kernels tool Produce a Wiener kernel for the process 2 Using the Equivalent Layer tool Create an equivalent layer grid corresponding to the dataset and the corrections specified This represents a smooth surface located between the terrain and the flight surface 3 Using the Equivalent Layer tool Use the equivalent layer grid created in stage 2 to produce a corrected line dataset Z field or grid dataset Using the Equivalent Layer tool gt gt To use Equivalent Layer with the INTREPID graphic user interface including creating a Wiener kernel for the process Stage 1 Calculating the Wiener kernel 1 Choose Wiener from the Filtering menu in the Project Manager or use the command wiener exe INTREPID displays the Wiener Kernels tool window
8. Intrepid Wiener Tool 3 2 Mg File Options Geometry Help Apply O Save Auto correlation matrix O Save Cross correlation matrix O Save Filtered Known Input 2 Ifyou have previously prepared file specifications and parameter settings for Wiener Kernels load the corresponding task specification file using Load Options from the File menu See Specifying input and output files for detailed instructions If all of the specifications are correct in this file go to step 9 If you wish to modify any settings carry out the following steps as required Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 2 Library Help Top lt 4 Back gt 3 These instructions for the beta version of this tool apply only to height corrections and reduction to the pole corrections in magnetic datasets Choose Magnetics from the Options menu niies Geometry Help Radiometrics Magnetics Other INTREPID displays the Magnetic Source Properties dialog box B Intrepid Wiener Tool 3 2 Magnetic Source Properties Susceptibility SI 1 000000 Inducing field strength nT 55000 000000 Inducing field azimuth degrees 9 000000 Inducing field inclination degrees gt 5 00000 Cancel 4 Specify the parameters according to your requirements Susceptibility Set this parameter to 1 You do not need to change Susceptibility for height corr
9. Line Dataset or Load Field as Grid Dataset as required from the File menu See Specifying input and output files for detailed instructions AGS Options Help Load Field as Line Dataset Load Field as Grid Dataset Load Platform Height as Line Dataset Load Ground Clearance as Line Dataset Load Platform Height as Grid Dataset specify Constant Platform Height Load Wiener Kernel specify Output Layer Grid Load Options save Options Load Layer Grid For Recalculation save Recalculated Yalues If any of the following fields or grids are available for use with the process and you wish to use them choose the corresponding option from the File menu and specify the grid band or line dataset field required See Specifying input and output files for detailed instructions Platform Height for Line Dataset Ground Clearance for Line Dataset Platform Height for Grid Dataset The File menu currently contains a Specify Constant Platform Height option which has an associated dialog box The default value of this parameter is 0 We recommend that you leave this option as it 1s Load the Wiener kernel for the process using Load Wiener Kernel from the File menu See Specifying input and output files for detailed instructions Equivalent Layer requires an extrapolated edge region to be added around the equivalent layer grid You can specify the method INTREPID uses for extrapolating data in the edge region See Creating
10. culation grid size of grid cell m Use this to specify the cell size for the equivalent layer grid If you are processing a line dataset specify the same or a slightly larger cell size for the grid as you would if you were gridding the line dataset The size you choose has a major effect on the calculation time We recommend that you make it as large as 1s reasonable for the desired data resolution If you are processing a grid dataset set the grid cell size the same as that of the input grid Calculation grid Height of grid above top of prism m Use this to specify the distance of the equivalent layer grid below the original survey height We recommend a height 2 3 of nominal ground clearance Calculation grid No of cells along side of grid Use this to specify the size of the matrix within which the Equivalent Layer calculation takes place Fora 15x15 cell Wiener kernel we recommend a setting of 101 For different sized Wiener kernels modify the setting proportionally Known Prism Prism width m Use this to specify the of the model used in the generation of the Wiener kernel It must be an odd multiple of the equivalent layer grid cell size We recommend a setting of three times the grid cell size Known Prism Prism depth extent m Use this to specify the thickness of the equivalent layer We recommend a Prism Depth of 0 1 of the equivalent layer grid cell size 7 Ifyou wish to save any intermediate results for checking the
11. e file with the settings current at the time of the Save Options operation For full instructions on creating and editing task specification files see INTREPID task specification job files RO6 gt gt To use a task specification file in an interactive Wiener Kernels or Equivalent Layer session Load the task specification job file File menu Load Options modify any settings as required then choose Apply gt gt To use a task specification file for a batch mode Wiener Kernels or Equivalent Layer task Type the command wiener exe or slayer exe with the switch batch followed by the name of the task specification file For example if you had an Equivalent Layer task specification file called surv329 job in the current directory you would use the command slayer exe batch surv329 job Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Library Help Top Task specification file example Library Help Top Equivalent Layer corrections T36 11 lt 4 Back gt Here is an example of a Wiener Kernels task specification file Process Begin Name wiener SaveKernel height_eba Parameters Begin rho air 1 293 rho_ground 2200 0 mu_air 0 00526 mu_ground 0 00528 xa 1 0 eps 1 0 N 1 0 susc 1 0 h 55000 0 az 0 0 inc 55 0 xSize 550 0 ySize 550 0 zSize 1000 0 dxGrid 50 0 dyGrid 50 0 htGrid 70 0 nxGrid 101 nyGrid
12. ections or reduction to the pole Inducing field strength nT Set this parameter to the correct Earth s core magnetic field intensity for the location of the dataset and survey date Inducing field azimuth degrees Set this parameter to the correct Earth s core magnetic field azimuth declination for the location of the dataset and survey date Inducing field inclination degrees Set this parameter to the correct Earth s core magnetic field inclination for the location of the dataset and survey date 5 Specify the Geometry parameters Choose Geometry from the Geometry menu File Options M uia Help Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 3 Library Help Top Library Help Top lt 4 Back gt INTREPID displays the Geometry dialog box Intrepid Wiener Tool 3 2 Geometry Known Prism Prism width m 250 000000 Prism depth extent mj 1000 000000 Calculation G rid Size of a grid cell mj 50 000000 Height of grid above top of prism mJ 70 00000 Ho of cells along side of grid Output Kernel No of cells along side of filter kernel Seneet J 6 Specify the parameters as required and choose OK Output kernel No of cells along side of filter kernel Use this to specify the size of the Wiener kernel The default size is 15 x 15 coefficients Specify different value if required Cal
13. for stage 3 or stages 2 and 3 of the process in a job file in order to repeat a similar task later or for some other reason use Save Options from the File menu See Specifying input and output files for detailed instructions 32 To exit from Equivalent Layer choose Quit from the File menu To view the current set of specifications choose Show from the Equivalent Layer window INTREPID displays them in a separate window See Displaying options and using task specification files for details and an example of a set of specifications You can view Help information by choosing options from the Help menu See Help below You can execute Equivalent Layer as a batch task using a task specification job file that you have previously prepared See Displaying options and using task specification files for details Performing stages 2 and 3 in separate sessions Library Help Top You can perform stages 2 and 3 in separate Equivalent Layer sessions This may be useful for line datasets which require large quantities of processing time gt gt To perform stage 2 only Exit from equivalent layer at the end of stage 2 gt gt To perform stage 3 only in a separate session after successful completion of stage 2 1 Carry out repeat stage 2 omitting steps 23 25 2 Carry out stage 3 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 8 Library Help Top 4 Back gt
14. ist of equivalent layer grid cells where this intersection occurs The report is a text file called oobe txt If you are using the Windows version select a field marker file with the extension LINE from inside the line dataset directory Load Platform Height as Grid Dataset If you are correcting a grid dataset and a survey height grid e g GPS height is available use this to specify the grid If you are using the Windows version select a field marker file with the extension GRID Load Wiener Kernel Use this to specify the Wiener kernel ker file for this process Specify Output Layer Grid Use this to specify a dataset name for the equivalent layer grid which is the result of stage 2 of the process Load Layer Grid for Recalculations Use this to specify the equivalent layer grid which resulted from stage 2 of the process and becomes an input for stage 3 of the process Save Recalculated Values Use this to specify the corrected line dataset Z field or the corrected grid dataset which is the result of stage 3 of the Equivalent Layer process Load Options If you wish to use an existing task specification file to specify the Equivalent Layer process use this menu option to specify the task specification file required INTREPID will load the file and use its contents to set all of the parameters for the Equivalent Layer process See Displaying options and using task specification files for more information Save Options If
15. ropriate field files as follows X coordinate location Y coordinate location See Vector dataset field aliases in INTREPID database file and data structures R05 for more information about aliases 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 9 Library Help Top 4 Back gt Load Field as Line Dataset If you are correcting a line dataset use this to specify the Z field that is to be corrected If you are using the Windows version select a field marker file with the extension LINE from inside the line dataset directory Load Field as Grid Dataset If you are correcting a grid dataset use this to specify the grid band that is to be corrected Jf you are using the Windows version select a field marker file with the extension GRID Load Platform Height as Line Dataset If you are correcting a line dataset and a height field 1s available usually the GPS height data use this to specify the survey height field If you are using the Windows version select a field marker file with the extension LINE from inside the line dataset directory Load Ground Clearance as Line Dataset If you are correcting a line dataset anda ground clearance field is available usually the Radar Altimeter data use this to specify the clearance field INTREPID will use this to detect places where the equivalent layer intersects the terrain out of bounds errors It will report a l
16. the extended region for filters in INTREPID spatial and time domain filters and transformations R13 for a discussion of edge regions Turn on the check box corresponding to the method you require We recommend that you use the Reflect Data Into Edges method Extrapolate Smoothly Into Edge INTREPID extrapolates values for the edge region from the original values in the grid Reflect Data Into Edges This method corresponds the Flipped Mirror Pad method described in INTREPID spatial and time domain filters and transformations R13 We recommend this method for general use Taper to Zero at Edges INTREPID tapers the values at the edge of the grid so that the values at the outside edge of the edge region are zero We recommend this method only for testing purposes 20 Select the degree of detrending for the grid used in the process by turning on the corresponding Detrend Degree check box We recommend that you use detrend degree 1 unless you have a specific reason for doing otherwise 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 6 Library Help Top Library Help Top q Back gt 21 Specify the options for the process using Options from the Options menu File cco Help INTREPID displays the Source Layer Control Options dialog box Intrepid slayer Tool 3 2 Source Layer Control Options Number ofiteraions 5 Smoothing 0 none 3 strong fs Field
17. you wish to save the current Equivalent Layer file specifications and parameter settings as an task specification file use this menu option to specify the filename and save the file See Displaying options and using task specification files for more information Apply After you have specified the Equivalent Layer task choose Apply INTREPID will perform the task and save the results Help You can use the Help menu to display help text Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Equivalent Layer corrections T36 10 Library Help Top 4 Back gt Exit To exit from Equivalent Layer choose Quit from the File menu Displaying options and using task specification files Displaying options gt gt To display the current file specifications and parameter settings Choose Show in the Equivalent Layer window INTREPID displays the current options 1n a separate report window Using task specification files You can store sets of file specifications and parameter settings for Wiener Kernels or Equivalent Layer in task specification job files gt gt To create a task specification file with the Wiener Kernels or Equivalent Layer tool 1 Specify all files and parameters 2 Preferably execute the task choose Apply to ensure that it will work 3 Choose Save Options from the File menu Specify a task specification file INTREPID will add the extension job INTREPID will create th
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