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Grid Operations (T25)

1. 4 Back gt Reasons for rotating a grid When you are using INTREPID there are two situations where you may wish to rotate a grid 1 The INTREPID Bicubic Spline algorithm creates a rotated grid if the survey lines were not acquired in a North South or East West direction In this case you would use the Gridop tool to unrotate the grid back to a rotation angle of zero If you want to use the INTREPID Decorrugation tool this tool requires that the input grid have rows and columns with North South or East West orientation However the INTREPID Minimum Curvature gridding algorithm creates grid columns which run parallel to the survey lines For survey lines which were not acquired in a North South or East West direction the grid rows and columns will not have North South or East West orientation In this case you will need to use Gridop to rotate the grid such that the input grid for Decorrugation has the correct orientation Extract grid from Multiband This option enables you extract a new single band grid from an existing multiband grid To extract a single band grid 1 Choose File gt Specify Input Grid and select and open your existing multiband grid From the Select Band dialog box select select the band name and choose OK Choose File gt Specify Output specify the single band grid file name and choose OK Choose Operation gt Extract grid from Multiband Choose Apply The Enter band number dialog box appears
2. e e e ex xex xex xe ox xex xex xe Input and output grid cell First pass along rows INTREPID Second pass down columns centroids interpolates values in line with INTREPID interpolates values for output grid cell centroids output grid using interpolated Input grid cell centroid values from first pass Output grid cell centroid x Interpolated value in line with output grid cell centroids INTREPID uses a spline curve to calculate the value for each new cell centroid in each column as illustrated in the following diagram Bi Cubic Spline Grid Resampling Output grid Input grid cell centroids Z cell centroid _ resampled so that rows and columns align with output R j grid Cell A value A boy Spline curve through input grid cell centroids Grid row or column X or Y 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 8 Library Help Top 4 Back gt Resampling Minimum Curvature INTREPID calculates the value of the new cell centroid using a weighted combination of surrounding original cell values in one pass The Minimum Curvature resampling process uses values from the current original grid row and from the two grid rows either side of the current grid row This method is an inverse of the Honour Original Data method See Minimum Curvature in Old Gridding T22 The following diagrams illustrate the process Minimum Curvature Grid Resampling Minim
3. Grid Operations T25 14 lt 4 Back gt lt 4 Back gt INTREPID User Manual Grid Operations T25 15 Library Help Top lt 4 Back gt Extracting components from a tensor grid You can extract grids of the following components and derived values from a tensor grid Component Description Auv Ane Buv Bne Guv G Falcon components ne XX XY ZX YY YZ ZZ Normal Component gradients Max Mid Min eigenvalue Principal components Trace SQRT 1st 1st 2nd 3rd scaled invariants CubeRT 2nd Ratio 12 11 Ratio of second to first scaled invariant This may help to tell if causative body has 2 dimensional characteristics See Pedersen L B Rasmussen T M The Gradient Tensor of Potential Field Anomalies Some Implications on Data Collection and Data Processing of Maps Geophysics 55 No 12 1558 1566 Phase Independent rotational component of tensor curvature We use this for enhancing subtle features and supressing strong features Scalar Magnitude David Clarke s suggestion measure of invariant amplitude Curvature Gradient Falcon Hilbert pair magnitude sqrt Guv2 Gne WormsTotalHorizontal For scalar and tensor grids sqrt Tzx Tyz Gradient gt gt To extract a grid of a component or calculated value from a tensor grid 1 Specify the input tensor grid Choose File gt Specify Input Grid Note Always specify the input grid before selecting
4. Input grid cell centroids Output grid cell centroid to be estimated _4 Resampled so that rows and columns align _ with output grid e e e e A A Ay A First differences between resampled input grid cells A A A Second differences between resampled input grid cells A A Third differences between resampled input grid cells Ay Fourth difference between resampled input grid cells INTREPID calculates the value for new cell by linear interpolation from the adjacent cells then modifies it using the 4th difference A This allows for the influence of the gradient near the new cell Library Help Top 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Grid Operations T25 7 Library Help Top 4 Back gt Resampling Cubic Spline Library Help Top This method involves two passes In the first pass INTREPID uses spline curves along the rows to calculate values that will correspond to the columns in the resampled grid In the second pass INTREPID uses the column values obtained in the first pass and original data values wherever the column coincides with a column from the original dataset to calculate a spline curve along each resampled column The following diagram illustrates the process Bi cubic spline resampling of a grid to change origin and cell size e e e ex x ex xex xe ex x ex xex xe 3 e e ex xex xex Xe e Xx xex xex xe bd bd e e ox xe x xe x xe ex xex xex xe
5. Leave the entry as the default of 1 1 Note you cannot create a multiband grid using this prompt Choose OK A message box appears Finished OK Choose OK Implant grid into Multiband Library Help Top This option enables you to combine existing single band grids into a new multiband grid To create a multiband grid in this way 1 a Ff W N O ON OD Choose File gt Specify Input Grid and select your first single band grid Choose File gt Specify Output and specify the multiband grid to be created Choose Operation gt Implant grid into Multiband Choose Apply In the Enter band number dialog box enter the number of bands to be in your multiband grid and the band number of the grid you specified in step 1 For example for a 3 band K U Th radiometric grid if you have just specified band 1 enter 3 1 in the pop up box Choose OK and dismiss the message box that tells you the operation is complete Choose File gt Specify Input Grid Select your next single band grid Choose Apply Enter the band number for this grid Repeat steps 7 8 until you have populated each band of your multiband grid 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 12 Library Help Top 4 Back gt Preparing grids to avoid Grid Merge or Stitch tool resampling In some situations you may wish to combine a pair of grids with minimal Grid Stitch tool resampling Using Grid Operations you can
6. Library Help Top 4 Back gt The Grid Operations tool gt gt To use the Grid Operations tool 1 8 Choose Grid Operations from the Grid menu of the Project Manager or use the command gridop exe INTREPID will open the Grid Operations window S Intrepid Gale 101 xi Fie Operation TensorGrids Parameters Precision Help Apply If you have previously prepared file specifications and parameter settings for Grid Operations 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 6 If you wish to modify any settings carry out the following steps as required Specify the input reference and output datasets for the operation Specify the reference dataset for resampling or smoothing if required See Specifying input and output files for detailed instructions If you are resampling specify the cell size required for your resampled grid and select the resampling process you wish to use See Resampling a grid for details If you are smoothing your grid specify the number of iterations required and the maximum residual difference for the minimum curvature smoothing process See Smoothing a grid for details Choose Apply INTREPID will process the input grid and create an output grid If you wish to save the parameters for this process in a task specifi
7. grid When finished for a small grid or As it proceeds for a large grid where it is using the tiling process See Optimising processing performance for large grids for details about small and large grids and tiling Exit from Grid Operations To exit from Grid Operations choose Quit from the File menu Help You can use the help menu to display help text on the topics shown in the menu illustration below sion GridOperations PDF INTREPID Contents PDF INTREPID Search PDF Apply Website Library GridOperations File Resampling Smoothing Parameters Apply Show GRF Library Help Top 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Grid Operations T25 18 Library Help Top 4 Back gt Using task specification files Library Help Top You can store sets of file specifications and parameter settings for Grid Operations in task specification job files As at V5 0 Intrepid all of this functionailty is moved to the GOOGLE protobuf syntax and the complete datamodel is published in the API section This gives the advantage of less code for Intrepid to maintaing and better parsers and a new way to do interprocess communication across disparate servers operating systems etc gt gt To create a task specification file with the Grid Operations tool 1 Specify all files and parameters 2 If possible execute the task choose Apply to e
8. otherwise the program will assume an output grid is required Detrend grid This operation creates an output grid that is detrended using the same 2D polynomial technology used in the Spectral domain grid filters tool GridFFT The required degree of the detrending can be set in the Parameters gt Detrend Polynomial Degree menu option Constructing and deconstructing tensor grids You can Construct a tensor grid from a number of component grids Extract components of a tensor grid as independent grids Constructing a tensor grid gt gt To construct a tensor grid from its components 1 Ensure that you have a set of six component grids With matching size location and cell size In ERMapper ers or semi format 2 Specify the output tensor grid Choose File gt Specify Output Grid 3 Choose TensorGrids gt Create from parts 4 Choose Apply INTREPID displays Open dialog boxes for the component grids XX XY ZX YY YZ ZZ 5 Specify the component grids INTREPID creates the tensor grid Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Library Help Top Library Help Top Parameters Precision Create from parts RNZN SR Max eigenvalue Mid eigenvalue Min eigenvalue Trace SQRT 1st CubeRT 2nd Ratio 12 11 Phase EigenAxis AUV ANE BUV BNE GUV average GNE average Scalar Magnitude Curvature Grad Worms THGrad 2012 Intrepid Geophysics
9. specify an origin and cell size for the resampled grid so it fits neatly with the grid to which you intend to stitch it This will reduce or eliminate the need for resampling during the Grid Stitch process Note The more recent INTREPID GridMerge tool incorporates a much superior resampling scheme to the earlier GridStitch thus reducing the need to perform resampling in Grid Operations gt gt To prepare grids for low resample stitching If you wish to stitch grids A and B and you will be resampling grid A to fit with grid B 1 Specify grid A as the input grid and grid B as the reference grid Specify a new grid cell size for the resampled dataset A For minimal resampling of A by Grid Stitch specify the cell size of A as a whole number multiple or fraction of the reference grid B cell size For no resampling of A by Grid Stitch specify the cell size of A equal to that of B INTREPID produces a resampled dataset A whose origin is a whole number of reference grid cells away from the origin of the reference grid B 2 Smooth grid A if necessary You can then use Grid Stitch to stitch grids A and B with minimal or no resampling Specify grid B as the grid to Calculate Geographic Reference From Specify the output cell size Mesh Size the same as that of grid B Grid Stitch will still perform adjustment and feathering as specified by you See Grid Stitch combining two grids T23 for full instructions on the us
10. EPID may scan through the grid number of iterations during the Minimum Curvature smoothing process Intrepid gridop To File Operation TensorGrids Parameters Precision Help Cellsize Min Curvature _OK Cancel Detrend Polynomial Degree Grf parameters 3 Choose Max Residual from the Parameters menu INTREPID displays the Minimum Curvature Maximum Residual dialog box File Operation TensorGrids Parameters Precision Help Intrepid gridop Tool 3 2 Min Curvature Max Residual 9 0500 0K _ Cancel 4 Each time INTREPID scans in its attempt to smooth the grid it may cause a change in the value of each interpolated cell As it completes each scan the change in each cell becomes smaller the interpolated values are becoming settled If all cell changes in a minimum curvature pass are less than the Maximum Residual the process will terminate Specify the Maximum Residual in the cell data units In this way you can specify the stage at which you consider that the cell values are sufficiently settled Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 10 Library Help Top Rotating a grid 4 Back gt The Grid Operations tool can rotate a grid dataset When a grid is rotated the result is a change in the orientation of the grid rows and columns Grid rotation is performed around the grid origin Positive angles are ant
11. INTREPID User Manual Grid Operations T25 1 Library Help Top 4 Back gt Grid Operations T25 Top The Grid Operations tool enables you to perform the following operations on gridded datasets Resample a grid to change its cell size and or origin The user can choose between four resampling methods Smooth a grid using the method of Minimum Curvature to improve its appearance Rotate a grid about the grid origin Decimate a grid by half and create an output grid with double the cell size Extract single band grids from a multi band grid Insert single band grids into a multi band grid Detrend a grid using the 2D least squares technology from grid filter Convert the internal grid values from Integer Real to Double Precision Export all non null values from a grid to an INTREPID point dataset Create GRF grids for your selected input grid You must supply date of survey acquisition and survey flying height Capture the grid outline into a shape or polygon file Save the difference of a grid from the reference grid without the requirement that the grids have the same origin and cell size Tensor Grid Operations Library Help Top Both standard Full tensor grids and the Falcon variant are supported in this tool Create a tensor grid from its component grids Deconstruct a tensor grid into its component grids 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Grid Operations T25 2
12. Poly In each case INTREPID displays an Open 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 Specify Input Grid Select the name of the grid dataset to be processed Specify Reference Grid The reference grid serves a distinctly different role depending on whether you are resampling or smoothing your dataset If you are resampling a grid and wish to change the origin use this to specify the name of the existing grid you want to align with See Preparing grids to avoid Grid Merge or Stitch tool resampling for an example of a situation where you would wish to change the origin If you are smoothing a grid use this to specify the name of the input dataset which contains the original values for honouring by the minimum curvature smoothing process If you do not specify a reference grid INTREPID uses the input grid as the reference grid Specify Output Grid Specify the name of the new grid dataset you are creating with this grid operation Load Options Select a Grdop task specification file to preload the interactive session with all the required file and parameter settings See Using task specification files for information about task specification files Save Options Save the current Grid Operations file specifications and parameter settings as a task specification file See Section U
13. cation 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 To exit from Grid Operations choose Quit from the File menu You can view Help information by choosing options from the Help menu See Help You can execute Grid Operations as a batch task using a task specification file job file that you have previously prepared See Using task specification files for details Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 3 Library Help Top lt 4 Back gt Specifying input and output files For resampling specify the original grid as the input grid The origin of the new grid can be set to that of an existing grid by selecting the existing grid as the reference grid at the file selection stage See Preparing grids to avoid Grid Merge or Stitch tool resampling for an example of a situation where you would wish to change the origin Specify a name for the output grid the resampled grid For other operations specify input and output grids Choose the corresponding options from the File menu to specify the datasets as described above File Operation TensorGrids Parameters Precision Help Specify Input Grid Specify Reference Grid Specify Output Grid Specify Output Dataset Load Options Save Options Save Outline
14. e of the Grid Stitch tool Create GRF grids The Create GRF grids option creates three grids that cover the extents of the currently selected input grid The grids created are the amplitude inclination and declination of the Earth s magnetic field They are calculated using the IGRF theoretical model The calculation requires you to specify a survey flying height above the spheroid GPS height and the survey acquisition date This is done in the Parameters gt GRF parameters menu This feature can be useful for comparing trends in your supplied dataset with predicted theory You may also wish to restore a regional trend back into your dataset You can use the Spreadsheet editor tool to add this trend back into your input grid 2012 Intrepid Geophysics 4 Back gt Library Help Top INTREPID User Manual Grid Operations T25 13 Library Help Top lt 4 Back gt Dump Non Null grid values to dataset This operation uses the non null values in your input grid to create a standard INTREPID point dataset containing X Y Z fields This is a reverse gridding process that enables you to regain some of the original observations from a grid This can be useful for Geomodeller as you sometimes need just a few points to indicate the observation of a contact See also the Dataset Sampler tool for similar functionality Dataset Sampler T25a Note when you Specify Output you must include a database extension eg DIR
15. example of an Grid Operations smoothing task specification file Process Begin Name gridop Input disk1 data mlevres_grid Reference disk1 data mlevel_grid Output disk1 data mlevsm_grid Parameters Begin Method Smoothing MaxResidual 0 04 Iterations 80 Parameters End Process End Here is an example of an Grid Operations smoothing task specification file which shows the syntax for most of the current options Process Begin Name gridop Input disk1 data mlevres_grid Output disk1 data grdop_grid Parameters Begin Method options are as follows Cubic_Spline Newton_4th_Order Minimum_curvature Cubic Smoothing Rotate SubSample GetBand PutBand Method Minimum_curvature Cellsize 15 MaxResidual 0 5 Iterations 100 OutputPrecision IEEE4ByteReal OutputRotation 0 0 only used for getband method GetBand Begin Band 1 GetBand End only used for putband method PutBand Begin Band 1 NBands PutBand End 1 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 20 Library Help Top 4 Back gt only used for subsample method SubSample Begin SS 0 SL 0 NL 100 NS 100 SINC 2 sub sample increment LINC 2 line increment SubSample End Parameters End Process End Library Help Top 2012 Intrepid Geophysics lt 4 Back gt
16. grid INTREPID uses the cell values in the input dataset you have specified INTREPID uses a minimum curvature smoothing process INTREPID will perform several iterations through the grid progressively examining and adjusting each cell in the input grid according to the values of the cells in the corresponding region of the reference grid INTREPID will repeat the process until it has either completed the number of specified iterations or the maximum residual change for all interpolated cells is less than the specified value 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 9 Library Help Top lt 4 Back gt gt gt To specify the smoothing process 1 Choose Minimum Curvature from the Operation menu File Operation TensorGrids Parameters Precision Help Resampling by Newton 4th Order opt smooth Resampling by Cubic Spline opt smooth Resampling by Minimum Curvature opt smooth Resampling by Cubic Polynomial opt smooth v Smoothing by Minimum Curvature Rotation Decimate grid half Extract grid from Multiband Implant grid into Multiband Promote grid to Double Precision Dump NonNull grid values to dataset Detrend grid Create GRF grids Save Outline of Grid Save Difference of Grid from Reference 2 Choose Iterations from the Parameters menu INTREPID displays the Minimum Curvature Iterations dialog box Use this box to specify the number of times that INTR
17. i clockwise You may declare the rotation angle parameter in either of two ways either by specifying the output grid rotation angle or as a rotation through the specified angle How to rotate a grid Library Help Top gt gt To specify rotation for a grid dataset 1 2 Ensure that you have correctly specified an input and output dataset Choose Rotation from the Operation menu INTREPID displays the Grid Rotation dialog box which reports the current rotation of the grid GRID ROTATION About The Origin Positive Angles anti clockwise Current Rotation Angle 45 0 Qutput Rotation Angle C Rotate Through Angle OK Cancel Specify the angle to or by which you wish to rotate the grid Do this by either a Selecting the target angle Output Rotation Angle OR b the amount of rotation Rotate Through Angle Then specify the angle in degrees positive angles are anticlockwise in the text box corresponding to the selected option Choose OK INTREPID displays the Rotation Check dialog box which reports the existing and proposed rotation settings for the grid Please Choose ROTATION CHECK Do You Want To D egre es Rotate From 2 45 0 Through 45 0 To 0 0 Yes No Choose Yes if the settings correspond to your requirements Choose Apply in the main window 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 11 Library Help Top
18. nsure 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 the 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 R06 files gt gt To use a task specification file in an interactive Grid Operations 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 Grid Operations task 1 Type the command gridop exe with the switch batch followed by the name and path if necessary of the task specification file For example if you had a task specification file called surv_conv job in the current directory you would use the commands gridop exe batch surv_conv job 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Grid Operations T25 19 Library Help Top lt 4 Back gt Task specification file examples Library Help Top Here is an example of an Grid Operations resampling task specification file Process Begin Name gridop Input disk1 data mlevel_grid Reference disk1 data mlnext_grid Output disk1 data mlevres_grid Parameters Begin Method Newton_4th_Order Cellsize 50 0 Parameters End Process End Here is an
19. om Multiband Implant grid into Multiband Promote grid to Double Precision Dump NonNull grid values to dataset Detrend grid Create GRF grids Save Outline of Grid Save Difference of Grid from Reference 3 Specify the grid cell size required for the resampling process Choose Cellsize from the Parameters menu File Operation TensorGrids Parameters Precision Help Iterations Max Residual Detrend Polynomial Degree INTREPID displays the Resampled Output Grid Cell Size dialog box Intrepid gridop Tool Resampled Output Grid Cell size 50 0000 OK Cancel You must specify the cell size before resampling the dataset The Cell Size text box may not contain the cell size of the input dataset Specify the required cell size for the output dataset in the distance units of the dataset and choose OK 1 If your dataset is geodetic latitude and longitude you need to specify the Grid Cell Size in degrees Library Help Top 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Grid Operations T25 6 Library Help Top lt 4 Back gt Resampling Newton 4th Difference This method calculates the value for the new cell from the values of the 5 nearest non Null cell values INTREPID adjusts the new value using the 4th difference to allow for the gradient in that neighbourhood The following diagram illustrates the process Newton 4th Difference Grid Resampling
20. s slower to compute than Newton 4th order Minimum Curvature is especially suited to potential field data It is our recommended method for magnetic or gravity datasets It also computes quickly on large grids and honours original values well Cubic Polynomial is especially suited to potential field data This method ensures the highest quality local estimates of a field that is Laplacian It provides genuinely 2 dimensional interpolation rather than one dimensional interpolation applied in orthogonal directions The default behavior of the Gridop tool is to resample the grid and then apply Minimum Curvature smoothing to the output grid The smoothing stage is optional and can be turned off by setting the number of smoothing iterations to zero 2012 Intrepid Geophysics lt 4 Back gt INTREPID User Manual Grid Operations T25 5 Library Help Top lt 4 Back gt gt gt To specify the resampling process 1 Specify input reference and output grids See Specifying input and output files for detailed instructions 2 Choose the method required from the Resampling menu See below for process descriptions File Operation TensorGrids Parameters Precision Help v Resampling by Newton 4th Order opt smooth Resampling by Cubic Spline opt smooth Resampling by Minimum Curvature opt smooth Resampling by Cubic Polynomial opt smooth Smoothing by Minimum Curvature Rotation Decimate grid half Extract grid fr
21. sing task specification files for more information Save Outline Poly Save the outline of the current Grid to a shape file of polygon dataset Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 4 Library Help Top 4 Back gt Resampling a grid Library Help Top The Resampling option creates a new grid with a specified cell size and an origin based on a specified reference grid If you do not specify a reference grid INTREPID uses the origin of the input grid It uses an interpolation process to calculate the value for each output cell The output cell size may be larger or smaller than the input grid cell size The output cell size does not need to be an exact multiple of the input grid cell size Each cell value in the output grid is derived from a single input grid cell or a group of neighbouring input grid cells There are four resampling methods available to interpolate values for the output cells They are Newton 4th Order Cubic Spline Minimum Curvature or Cubic Polynomial Newton 4th Order is our recommended general purpose method It works well for a wide range of datasets It is the best method to use for radiometric or electromagnetic data It computes quickly on large grids and honours the original values faithfully Cubic Spline is best suited to datasets with small amplitude changes between cells ie not radiometric or electromagnetic data It i
22. the operation that you want to perform 2 Choose the component or derived values that you want to estract Choose the required option from the TensorGrid menu Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 16 Library Help Top lt 4 Back gt Operation Parameters Precision Create from parts RNS SR Max eigenvalue Mid eigenvalue Min eigenvalue Trace SQRT 1st vV CubeRT 2nd Ratio 12 11 Phase EigenAxis M 3 Choose Apply INTREPID displays a Save As dialog box for the component or derived values 4 Specify the output dataset name INTREPID extracts and saves the component grid Library Help Top 2012 Intrepid Geophysics 4 Back gt INTREPID User Manual Grid Operations T25 17 Library Help Top lt 4 Back gt Optimising processing performance for large grids For large grids INTREPID uses a tiling system This involves processing the grid a section at a time You can optimise the performance of your computer by adjusting the value of the INTREPID_MEMORY system parameter Apart from this optimising adjustment the tiling process and the decision to use it is automatic See INTREPID Memory limits and tiling in Configuring and using INTREPID R04 for information about INTREPID_MEMORY Apply When you choose Apply INTREPID performs the resampling or smoothing grid operation as specified by you saving the
23. um Curvature Grid Resampling ideal case of aligned cell centroids Input grid cell centroids e Input grid cell centroids amp e e e e re y e e e e e e e Y N e a e e e e e e e A e e e e e e e Output grid cell centroid to be estimated INTREPID bases the value on a weighted combination of surrounding input cell values Output grid cell centroid to be estimated honouring the exact location of the output cell Resampling Cubic Polynomial The Cubic Polynomial method is applicable to resampling within a grid cell where the values of the field at the corners and also the gradients are known quantities An analytic function is used locally to calculate the field value at the required point This method is often used in contouring as well to ensure high quality local estimates of a field that is Laplacian Smoothing a grid Library Help Top After resampling is completed the resampled grid may appear pixelated or coarse grained Intrepid will automatically apply Minimum Curvature smoothing to the resampled grid You can control the amount of smoothing by changing the number of smoothing iterations or turn it off completely by setting the number of iterations to Zero Smoothing can also be run as a separate operation on its own You may have a grid which for some reason or other appears pixelated You can improve its appearance by smoothing it Specify your grid as the input grid If you do not specify a reference

Grid Operations (T25)

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