Line filtering (G15) - Intrepid Geophysics
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1. Save Power Spectrum Spectral Power Vs Frequency in cycles km Save Fourier Components Quit When you have finished inspecting the spec file dismiss the Power Spectrum box by choosing Quit from the File menu Power Spectrum Filter Name VerticalDerivative Untitled Filter Size 4096 Line Name Line 140201 Signal Field magfinal Bearing 270 Units Cycles kilometer Wave Number Power 0 000000 Null 0 069234 1 051153e 001 0 138467 1 051363e 001 0 207701 1 274858e 001 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 10 Library Help Top lt 4 Back gt 0 276935 8 913523e 000 4 Exit from the Line Filter tool To exit from the Line Filter tool choose Quit from the File menu Gradient Data Example from Cookbook If you wish to see how we handle FTG data start again but this time navigate to the Intrepid V4 5 sample_data cookbooks tensors Aurizonia A_1_DB directory Start the line filtering tool choose Open Line Dataset choose Geo located dataset then select Aurizonia tensor FormedTensor DIR Choose the Field T fa tensor This represents a FreeAir measured gravity tensor gradients a Z Select Signal Field Po N ee Altitude ect Line Dataset S di cookbooks tensors Aurzonia A1 DB 4 Search A_1 DE m Clearance janize Mew folder E Gil corr_Component2. PM 22 2MB Generic Data file i aa 7 alburydata ddf 12 02 2008 4 16 12 PM 6958 Data Description File i N i _ aburydata des 13 02 2008 1 10 50 PM 852B Fie i cases E aburydata dfn 12 02 2008 4 01 18 PM iKB Fie ji onig aburydata zip 19 02 2008 12 27 38 PM 39MB Zip Archive J cedis 78 anomt_griders 27 03 2003 1 38 52M OB Intrepid Grid Fe Ti anoml_grid1 ers 10 12 2012 1 43 38 PM 0B Intrepid Grid File i J fites FF cho6 _1 job 26 07 2012 4 27 24 PM 1KB Intrepid job fie an F ch07_1 job 14 08 2008 11 23 42 AM 9468 Intrepid job file a fom FT c09 job 27 03 2003 1 38 52PM 322B Intrepid job fle ip heb Thos 2j 14 08 2008 11 23 42 AM 582B Intrepidjob fle i images FF chto_1job 26 07 2012 4 27 24 PM 1KB Intrepid job fie heme FT chtt_2job 26 07 2012 4 27 24 PM 1KB Intrepid job fle f H Fhia 0b 14 08 2008 11 23 42 AM 5358 Intrepidjob fle F n lynxdata n manuals m nlut a Jl proj m sample_data a gt cookbooks E g examples 8 guided _tours n d geosoft_datasets 2 Open the input dataset and field Library Help Top From the File menu choose Load Line Dataset The Sample Mode dialog box appears Under Select Resampling Mode select Geo Located Choose OK This is the vital decision regarding what context you are wanting to operate in The Select Line Dataset dialog box appears Select the dataset albury DIR and choose Open The Select Signal Field dialog box appears Select magfinal from the list of dataset
3. fields If you do not have magfinal in your dataset you may select any other magnetic data field for example rawmag Choose OK The Select Sensor Altitude m amp Select Optional Drape Altitude m dialog boxes appear Choose SKIP These are when you wnat to do an altitude adjustment of your signal This can also be a vector tensor or quaternion field 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Library Help Top Library Help Top E Intrepid Line Fitter Help Load Line Dataset Save Filtered Z Trace As Load Filter Save Filter Load Options Save Options Select Resampling Mode Geo Located Requires X Y Fields C Time Based Requires a Fiducial Field Factor to convert your fiducial to second s 10 00 sec Data Points Edit Database Aliases OK Cancel C Fixed Resample interval of 2012 Intrepid Geophysics D Select Line Dataset Line filtering G15 5 ee D e guided tours intrepid datasets ow Fy tours gt intrepid datasets vit Organize ole Favorites BB Desktop 2 Recent Places Downloads T Libraries Documente d Music i Pictures E Videos A Homegroup 1 Computer Be Local Disk C We des_fast Dx New folder File name albury DIR s Unspecified 23 d albury aiburyl d ebagoolsA Lh ebegools 8 J tbagocla F db ebagocla_ d ebegoola_ ST a euio s euler_ss D
4. having to do it one by one A Yes this can be done easily as a batch operation There are example batch files in install_path sample_data Examples jobs Q The gravity inversion filter looks interesting What is it A This is an implementation of a paper by Murthy and Rao from Computers and Geosciences Vol 15 No 7 A profile of gravity data is inverted to yield either 1 depths to the top of the basement surface below each point of gravity anomalies or 2 anomaly of structure Q Can I chain two filters together and apply them in the same operation A Yes there is a composite option that allows you to do this Q Does the filter use FIR and IIR nethods A Yes most standard digital operations are supported together with several quite specialist geophysical ones Q Is there a limit to the number of samples in a profile A Over 8 million observations of a full tensor gradient signal have successfully been filtered using this tool for one profile This is close to a current limit 2012 Intrepid Geophysics 4 Back gt
5. in the dataset Choose Process The Lines to Filter dialog box appears The following options are available for selecting the lines that you want to process Select lines from a list e Select a range of lines e Select a single line e Select all lines In this exercise we use the default option Select All Lines which processes all the lines Choose OK The Save Filtered Signal Field dialog box appears In the Enter New Field Name text box delete newZ Enter the new output field name magivd Choose OK A progress bar appears and INTREPID begins processing the lines in the dataset When the progress box disappears the processing 1s complete Leave the Line Filter tool window open and move to the next exercise Save the filter description file and the power spectrum Library Help Top INTREPID allows you to save and load your filter parameters using special files called filter description files fdf If you want to run the same filter at a later date it is useful to be able to save the current filter description In fact this 1s a necessary step if you want to run the filtering as a batch process The following section describes how you can save and load filters as filter description files and also how to get access to power spectra 1 Save the current filter description From the Spectral menu choose Save Filter The Vertical Derivative Filter Properties dialog box appears In the Filter Name text box change VerticalDeri
6. w r x EE Intrepid Line Fitter a m on 2 8 Ey Intrepid Line Filter e _ baha File Spatial Spectral Special Help File Spatial Spectral Special Help New FIR Fourier gt Band Pass Line 140201 Signal Field magfinal Bearing 270 Composite Band Reject 120 Edit Current a High Pass Current Properties Kaiser Band Pass Vertical Derivative Filter Properties Vertical Derivative Horizontal Derivative Vertical Derivative Filter Properties Upward Continuation Filter Name erticalDerivative Untitl Downward Continuation Filter Space FOURIER Variable Continuation Filter Properties Reduction To Pole Order of differentiation Vertical Component No of Weight Control Points 12 Horizontal Component Extend Data Using Fourier Hilbert C Zero Pad Mirror Pad Data C Flipped Mirror Pad Data Roll Off Using Bartlett Window Hanning Window C Parzen Window Roll Off Window Size 18 points OK Cancel Under Filter Properties you can specify order of the vertical derivative The default is 1 Select OK to dismiss the dialog box The panel under Filtered Line Display displays the filtered output signal At this point you are simply previewing the effect of the filter No output has been saved in the dataset yet Use the control buttons to navigate Use Previous and Next to preview the effect of the filter on differe
7. 7 30 859957 0 Nyquist Frequency 141 791 cycles km C Use Fixed Spacing 0 00352632418 km Use Average Spacing 0 00352632418 km Minimum Sample Spacing 0 00180201334 km Maximum Sample Spacing 0 00810915198 km Interpolation Method Number of points to take into account at line ends for line end detrending 10 Average Line Direction North to top Nulls Linear C Cubic Spline C Nearest Neighbour C DC shift Use line ends C Least square fit l Detrend Raw and Filtered Line T Overlay Filtered line Zoom Both Lines OK Cancel Under Display Options observe that the Detrend Displayed Line box is checked This means that the default behavior is to remove the trend from the input data before the signal is displayed Clear the Detrend Displayed Line check box and then choose OK The input signal will appear as it really 1s with no detrending applied Open the properties dialog box again and check the Detrend Displayed Line box Observe how the shape of the input signal changes depending on whether the detrending function is turned on or off 2012 Intrepid Geophysics Line filtering G15 INTREPID User Manual Line filtering G15 7 Library Help Top Library Help Top lt 4 Back gt 4 Apply a filter to the input signal From the Spectral menu choose New FIR Fourier gt Vertical Derivative The Vertical Derivative Filter Properties dialog box appears
8. Gridmerge Ji potya d poe 5 albury DIR T aboa me Any Table DIR gdt shp lt 4 Back gt Select Signal Fiel line linetype magd magdigrt maqdloop Ok Cancel 4 Back gt INTREPID User Manual Library Help Top Library Help Top The main filtering user interface appears in the Line Filter window The top panel displays the input unfiltered signal and the bottom panel displays the output filtered signal Since there is currently no filter chosen the input and output signal are the same m FE Intrepid Line Filter a moe File Spatial Spectral Special Help Line 140201 Signal Field magfinal Bearing 270 lt lt Previous J Process J Goto Power Spectrum Filtered Line Displa Right mouse click the input signal area top panel A properties dialog box appears It contains useful statistical information about the current line including the number of samples statistics sample spacing line direction and Examine the display options some display options Line Statistics Sample Spacing Detrend Method Dis play Options Line 140201 Signal Field magfinal Bearing 270 a I Original No of Samples 2543 No of leading Nulls 0 No of Trailing Nulls 0 Trimmed No of Samples 2543 No of Interpolated Samples 2543 Field Minimum Maximum Mean StdDev 9 866870880127 120 829229179291 15 18610068723
9. INTREPID User Manual Line filtering G15 1 Library Help Top lt 4 Back gt Line filtering G15 Top Line filtering is the process of applying a filtering operation to the geophysical line or profile data as opposed to filtering the gridded data Some experience with line filtering and a familiarity with the more common filters is essential for understanding how geophysical data is manipulated The INTREPID Line Filter tool can be used to apply either spectral Fourier or convolution Spatial filters Context of this guided tour Library Help Top In the context of your data processing cycle Line filtering may be carried out at any stage of the processing sequence Your signal maybe be as simple as a set of samples a time series or fully geolocated samples that are more or less in a straight line Signal is defined in the genric INTREPID sense and can mean scalar measures of magnetics gravity elevations or gradients vectors and tensors that have purpose built algebra behind them For magnetic data it is often applied to the final processed data for the purposes of producing an enhanced product for interpretation This Guided Tour can be followed at any stage of the processing sequence If you have a final levelled and fully processed magnetic data field in your dataset use that Otherwise you can use any magnetic data field created at any stage of the processing Location of sample data for Guided Tours We pro
10. nt lines Choose Goto to select and preview any line in the dataset Right click the input signal area In the properties dialog box under Display Options check the box next Overlay Filtered line Select OK The Line Filter tool displays the input and output signal together using the same scale in the input panel Since the dynamic ranges are very different the vertical derivative signal will appear mainly as a straight line Turn the Overlay Filtered line option off Use the zoom feature Now try zooming in on either the input or output signal To do this using the left mouse button drag to define the rectangular area you want to zoom to Zoom in to the filtered signal and observe how the vertical derivative filter enhances noise in the data To zoom back out and view the whole line using the left mouse button double click the zoomed section of signal Intrepid Line Filter v4 1 MSI for Windows 2003 by KRAMER Build 317 intrepid Line Filter v4 1 MSI for Windows 2003 by KRAMER Build 317 File Spatel Spectral Special Help Fie Spatial Spectral Special Help i Line 140201 Signal Field meafinn APE ESB ywRisel Dearing 270 Filtered Line Displa Seeds T T T 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 8 Library Help Top 4 Back gt 7 Apply the filter to the dataset Now we are ready to process the lines using the vertical derivative filter and create a new output field
11. omponent or gradient filtering support Sampling modes The Line Filter tool operates in one of three different sampling modes 1 Spatial mode Every data point has an associated X and Y value 2 Time based mode Every data point has an associated time value or fiducial 3 Fixed sample mode The data is just regularly sampled data with no time or spatial associations Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 4 Library Help Top Steps to follow lt 4 Back gt Filter input and create output field 1 Launch the Line Filter tool Start the Project Manager Navigate to the directory install_path sample_data guided_tours intrepid datasets From the Filtering menu launch Line Filter The INTREPID Line Filter tool window appears r O ine Fier File Dataset Editing Display Levelling Gridding filtering Mapping Gravity Radiometrics Interpretation Utilities Betas Help File Help urrent Folder C Intrepid V4 5 sample_data guided_tol Line Filter t J batch logs 3 Grid FFT Last Modified Size File type i Dev EY Grid Commotion 15 02 2008 10 52 42 AM 0B Intrepid dataset aoe ji 08 12 2012 4 28 37 PM OB Intrepid dataset J GeoModeler fe Po cedente 10 12 2012 2 17 16 PM OB Intrepid Grd Fie len eons 17 epid Gr Jb aig Ti albury_rawmag ers 10 12 2012 2 47 49 PM 0B Intrepid Grid File J J T aburydata dat 12 02 2008 4 01 32
12. r box appears This displays a list of pre defined filters that are provided with INTREPID Choose any one of the filters and choose OK INTREPID will load the filter and preview it for the current line To check which filter is currently loaded choose Current Properties from either the Spatial Spectral or Special menus The filter properties box will appear Another way to do this is to right click the output signal area Compute and save the power spectrum The INTREPID Line Filter tool provides access to the power spectrum for any line Choose Power Spectrum The Power Spectrum box appears The box displays graphs of power spectra computed for the current line Spectra are displayed for the input data in black and the output data in white From the File menu choose Save Power Spectrum The Save Power Spectrum dialog box appears Enter power for the filename and choose Save INTREPID will create a file called Your_Name spec in your working directory This file contains the power spectrum calculated for the output data only Load the file into an editor for example Excel and you can do depth estimates etc we have made this something that can be automated as well when you have large profile databases and wish to create your own proceedures for estimating either depths or properties of rocks using a moving window along each profile The numbers in the file have the units of wavenumber X and log of power Y Power spectrum iin
13. reoPlot of EigenVectors N to top Dis play Options Detrend Raw and Filtered Line Overlay Filtered line Zoom Both Lines OK Cancel Tensor Low Pass Filter A few standard convolution filters have been implimented for tensors Choose the Low Pass from the Pull right menu Then left click in top choose superimpose Pe ee a Po LL tie File Spatial Spectral Help _ Mew FIR Fourier Eand Pass Composite Band Reject earing 135 100 Edit Current Low Pass High Pass Current Properties AAT TAL it a ao lt TT ool baa li rit Py Je ry RAR SLOCUM AO cn Hp l A File Spatial Spectral Help Line 11 Signal Field T_fa_tensor Bearing 135 100 50 ti f PADNE A EE T i Z 100 By 2000 4000 6000 8000 10000 12000 Dy lt lt Previous Line filtered using LowPass Untitled Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 13 Library Help Top q Back gt Key points for this guided tour In this guided tour you have e Used the Line Filter tool to filter some data and save the filtered data as a new field in the dataset Learned how INTREPID manages filter description files e Used the tool to save power spectra to a file Hada glimpse of the Full Tensor support offered in this tool Frequently Asked Questions Library Help Top Q Can I write out power spectra for all the lines without
14. s A ae corr_Gradients ee r Name Date modified Flight E Desktop a Unspecified 2 aoe aaa enemas Ji Aurizonia_tensor_FormedTensor 30 11 2012 2 39 PN Line F Downloads Aurizonia_tensor_FormedTensor DIR 25 11 2012 7 48 PD ao Librari SRTM_Terrain SEIE TC_T_100_tensor Documents T_BG_200_tensor d i Music _fa_tensor Pictures L Videos Ok Cancel Homegroup Computer fy Local Disk C Ja des_fast D le m Filename Aurizonia_tensor_FormedTensor DIR Y This is the initial tensor profiule screen without any filters being applied The characteristic for a profile of tensor data is the lack of any long wavelength trends with all the components around zero The before and after colours are changed slightly in the superimpose view so you can make out which is which Library Help Top 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Line filtering G15 11 Library Help Top 4 Back gt File Spatial Spectral Help Line 11 Signal Field T_ta_tensor Bearing 135 m rl y 1 s i M L i a ie L SE A Ay EE zA SAS 100 2000 4000 6000 8000 10000 12000 lt lt Previous 100 50 PRAS Vole 100 000 4000 6000 a00 10000 12000 Tensor Statistical Report As with scalar data a right mouse button 1n the top window brings yup a dialog that summarises the current lines statistical properties These have been e
15. ser might 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 2 Library Help Top 4 Back gt also gain some trial and error insights into the capbilities of the software just by testing the Project Manger s ability to preview and describe the attributes of each of the cookbook datasets Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 3 Library Help Top 4 Back gt Overview Line filtering is a basic and fundamental data processing operation which is used in numerous data processing applications Line filtering is routinely used to remove noise from radar altimeter and cosmic data during the processing of radiometrics It is used implicitly in procedures such as tie line levelling decorrugation and microlevelling It is used to separate different frequencies for interpretation analysis Filters available The INTREPID Line Filter tool supports spectral Fourier and convolution Spatial filters as well as some special depth estimation filters The more commonly used filters include e Moving average and median e Non linear Naudy Huighpass lowpass and bandpass e Vertical derivative e Phillips depth estimation e Gravity section basement modelling Murty amp Rao e Full tensor gradient support for high pass low pass and band pass e Quaternian filtering for roll pitch and yaw rotation data e Full vector c
16. vative Untitled to VerticalDerivative 1 for the new field name Choose OK E Intrepid Line Filter ms File Spatial Spectral Special Help New FIR Fourier Vertical Derivative Filter Properties Vertical Derivative Filter Properties Filter Name YerticalDerivative Untitled Filter Space FOURIER No of Weight Control Points LJ 7 5 Filter Properties Extend Data Using I Order of differentiation C Zero Pad Mirror Pad Data C Flipped Mirror Pad Data Roll Off Using No of Weight Control Points 4 Extend Data Using Mi C Flipped Mirror Pad Data Roll Off Using Roll Off Window Size The filter specification has now been saved into a filter description file called VerticalDerivative 1 fdf All of the fdf files are stored in a directory called filters within your INTREPID installation As of this version of INTREPID it is possible to embed a fileter description into a line filter job file rather than call out to a seperate fdf file At V5 0 this also generalises to using GOOGLE protobuf syntax for all filter descriptions and tasks 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 9 Library Help Top Library Help Top lt 4 Back gt 2 Load a new filter description From the Spectral menu choose Load Filter The Available Filters paramete
17. vide two complete sets of sample datasets one in INTREPID format and one in Geosoft format INTREPID works equally well with both formats When you want to open a dataset navigate to the directory containing the required data format Where install_pathis the path of your INTREPID installation the project directories for the Guided Tours sample data are install_path sample_data guided_tours intrepid_ datasets and install_path sample_data guided_tours geosoft_datasets For example if INTREPID is installed in C Program Files Intrepid Intrepid4 5 nnn then you can find the INTREPID format sample data at C Program Files Intrepid Intrepid4 5 nnn sample_data guided_tours intrepid_ datasets This is the default location for the sample data If you have installed INTREPID normally the data resides there If you have installed INTREPID elsewhere the exercises will work just as well Just use the appropriate pathnames For more information about installing the sample data see Sample datasets installing locating naming in INTREPID Guided Tours Introduction G01 For a more detailed description of INTREPID datasets see Introduction to the INTREPID database G20 For even more detail see INTREPID database file and data structures R05 Location of sample data for CookBooks Right next to the Guided tours data is a rich set of more exotic geophysics datasets and grids already prepared for the cookbook training sessions A casual u
18. xtenbded beyond normal stats to include characteristics of the tensor such as the average eigenvector direction and angular spread for each eigenvector We then represent these in a stereonet style plot mimic The size of the Black Green and Red circle reflects the angular dirpserion of the eigenvector Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Line filtering G15 12 Library Help Top 4 Back gt Line Statistics Original No of Samples 215 No of leading Nulls 0 No of Trailing Nulls 0 Trimmed No of Samples 215 No of Interpolated Samples 215 Field Minimum Maximum Mean StdDev Nulls Declination Inclination Dispersion EV1 15 1411060843 108 599718359 42 1589849192 16 3906 0 6 129 9 322 59 283 EV2 39 3158803763 47 97522828677 4 03561773815 13 8906 93 751 5 168 55 091 EV3 147 167612915 12 4781 499526 46 194841 4585 18 6711 142 742 81 703 45 080 Mean Trace 0 000238801163206 EigenVector Volume 0 969 Nyquist Frequency 8 59607 cycles km Sample Spacing Use Fixed Spacing 0 0581660834 km Use Average Spacing 0 0581660834 km Minimum Sample Spacing 0 0478173609 km Maximum Sample Spacing 0 0616611709 km Interpolation Method Linear C Cubic Spline Nearest Neighbour Detrend Method C DC shift Use line ends C Least square fit Number of points to take into account at line ends for line end detrending Average Line Direction North to top Ste
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