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iMOD User Manual version 4.4 (html)


6.7IDF Options

iMOD supports several basic functionalities that manipulate IDF-files:


6.7.1IDF Value

WHY?
IDF-files are raster files with (non)-equidistant rastersizes. Interactive inspection of the raster with the IDF Value option is a quick and easy way to check the raster values.

WHAT?
IDF Value allows you to view particular rastercell values for a single IDF-file, or multiple IDF-files. iMOD will read the IDF values underneath the current mouse position.

HOW?
In the Map tab of the iMOD Manager window, click the Map Value ( pictures/h4/image271.png ) button to open the Map Value window. Otherwise, use the shortcut F3 or right-click anywhere on the canvas to open the popup menu. Select the option IDF Options and then choose IDF Analyse. Or alternatively, select the menu option Map, choose the option IDF Options and then IDF Analyse.

Map Value Window:

pictures/h6-h71/mapvalue_window.png

Current Location

This field shows the current location of the mouse on the canvas. Press the LEFT mouse button to freeze the current location. Restart inspection over the canvas by pressing the LEFT mouse button again.

IDF

This column in the table shows the IDF selected in the iMOD Manager and part of the inspection with MapValue.

Values

This column shows the value of the IDF (column 1) for the current location. Values that are greater than zero will be coloured red, less than zero become blue.

Transf.

This column shows the transformation that could take place, see for more information about this the syntax of the IDF-file and how to apply a transformation.

Cell
Indices

This column shows the column and row number of the selected IDF-files, e.g. Cell Indices=C32;R12 to represent column 32 and row 12 respectively. There is no need that the inspected IDF-files have identical dimension and/or raster discretization. Whenever the mouse is positioned outside the limits of the IDF, Cell Indices=Outside. In case the inspector works with a rectangle/polygon, the Cell Indices will show the minimum and maximum values for the column and row numbers that are within the rectangle/polygon, e.g. Cell Indices=C40-32;R32-54.

Value Format:

Choose the preferred value format from the dropdown menu. You can choose from: Real (e.g. 2.345), Integer (e.g. 002) and Scientific notation (0.2345E+01).

Decimal places:

Change this value to set the total amount of decimal values (values behind the point), the possible range is 0-15.

Help …

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the MapValue window. Alternatively the MapValue window can be closed by clicking the RIGHT mouse button anywhere on the canvas.

Note: All selected files in the iMOD Manager will be listed in the Map Value window, however, IPFs, IFFs, GENs and ISGs will be left out automatically. There is no need to deselect them before clicking the Map Value button. Whenever a MDF-file is selected, all IDF-files within the MDF-file will be displayed and also the MDF-filename.

Map Value window filled with items from a MDF-file:

pictures/h6-h71/mapvalue_window_mdf.png

Note: The menu options Move, Zoom In, Zoom Out, Zoom Full and Zoom Rectangle are available during the Map Value exercise.

Note: Click the left mouse button to stop hovering over the graphical display. It will freeze the values in the Map Value window. Start hovering again by clicking the left mouse button again, terminate the entire functionality by clicking the right mouse button.

On default, the Map Value window will operate as a point inspector, in other words, the value will be read for the current position of the mouse. Click the menu option Map, the option IDF Options and then the option IDF Analyse to display the following options to alter this:


6.7.2IDF Export

WHY?
IDF-files have a specific format. The export to a format readable in other software applications makes it possible to use the IDF-files outside iMOD.

WHAT?
The IDF-files can be exported in several formats.

HOW?
Choose the option Map from the main menu, choose IDF Options and then IDF Export to display the following menu options:

For both export formats the following options are available:


6.7.3IDF Calculator

WHY?
Arithmetic operations enable the creation of new IDF-files.

WHAT?
The IDF Calculator works with IDF-files as input and enables to:

HOW?
The IDF Calculator can be displayed at any time from the iMOD Manager, click the Calculator button and/or use the Map option from the main menu (or the popup menu that displays whenever you click your right mouse button on the graphical window), choose IDF Options and then the option IDF Calculate. The following Map Operations window will be displayed.

Map Operation window, Algebra tab:

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Map A

Displays the first IDF. On default it will display the first selected IDF from the iMOD Manager, click the button Open IDF to open a different one.

Map B

Displays the second IDF. On default it will display the second selected IDF from the iMOD Manager, click the button Open IDF to open a different one.

Map C

Enter the name of the resulting IDF. On default it will use the name DIFF.IDF that will be saved in the TMP-folder of the USER-folder.


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Open IDF
Click this button to select an IDF-file from a folder

Formulae

Enter the formulae to be used. The syntax of the formulae is that the IDF-names entered as Map A, Map B and Map C are represented by the characters A, B and C, respectively. The example C=A-B means that the values of Map A will be subtracted by the values in Map B.
The following operators are available in the formulae:
+
Adds a values
-
Subtracts a value
/
Divides a value
*
Multiplies a value
?
Takes the first NoDataValue found in Map A then Map B
\(<\)
Takes the smallest from both values between Map A and Map B
\(>\)
Takes the largest from both values between Map A and Map B.

The following functions are available in the formulae:
ABS()
Takes the absolute value of the expression between brackets.
LOG()
Takes the log-10 value of the expression between brackets.
EXP()
Takes the exponent of the expression between brackets.
GTP()
Computes the groundwaterclass (“grondwatertrap”). Enter a mean highest groundwaterlevel for Map A and the mean lowest groundwater level for Map B.
SGN()
Assigns a individual value for each combination of computation, it results the following values.
both values are negative
A \(>\) B = 1
A \(<\) B = 2
both values are positive
A \(<\) B = 3
A \(>\) B = 4
value A is positive and value B is negative
5
value A is negative and value B is positive
6
LN()
computes the natural log-value.

Expression

The Formulae entered is translated into an Expression which will be used, eventually. The expression can be used to check whether the formulae has been filled in correctly.

Note: It is possible to include constant values in the Formulae, e.g. [C=1.5*A] which means that all values in Map A will be multiplied with a factor of 1.5. Be aware that the number should come before Map A as in the formulae [C=A*1.5] the constant value is ignored. This can be extended to another factor to be used for Map B, e.g. [C=1.5*A-0.5/B].
It should be noticed that these constant value are rounded to a single precision real (8 digit number), so the entered value 0.1234567890 becomes 0.12345678 in the Expression.

Example of the Formulae:

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Ignore
NoData_ Value

Check this option to ignore the NoDataValues in the IDF-files.
On default cells equal to the NoDataValue of the IDF will be excluded in the computation.

Use
NoData_ Value as value

Check this option to use the NoDataValues in the computation.
Specify the value to replace the NoDataValue of the IDFs.
On default the value 0.0 is used.

Apply function for …

After the calculation, this option gives values smaller than given/entered absolute value a nodata value, e.g. C=A-B if C<0.1 C=nodata.

Transform into …

Check this option to force that the resulting IDF (Map C) will have equidistant cellsizes. Whenever any of the selected IDF-files (Map A and/or Map B) is an IDF-file with non-equidistant cellsizes, the smallest cellsize in one of these will be used to determine the cellsize of Map C.

Use *.gen

Check this option to force that the results of Map C will be computed inside the polygons that are defined in the entered *.GEN-file (*.gen).

*.gen

Enter the *.GEN-file with polygons


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Open File
Click this button to select a *.GEN file

Select the extent
for which the
computation apllies:

Click one of the following options:

  • Window, to force that the results of Map C will be computed for the current ZoomLevel only;

  • Map A, to force that the results of Map C will be computed for the extent of Map A.

  • • x1,y1,x2,y2, to enter the coordinates of a specific window

Compute...

Click this button to start the computation, it closes the Map Operations window afterwards.

Help ...

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the Map Operations window.

Map Operation window, Scale/Size tab:

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Map A

Displays the IDF to be scaled. On default it will display the selected IDF in the iMOD Manager, click the Open IDF button to open a different one.


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Open IDF
Click this button to select an IDF-file from a folder.

Map C

Enter the name of the resulting IDF. On default it will use the IDF-file from Map A and add the postfix SCALED to it, so the IDF-name will change from *.IDF into *_SCALED.IDF.

Scale

Enter the new cell size of the IDF. The resulting IDF will be an equidistant IDF with this cellsize.

Formulae

Upscale Formulae

Select a Formulae to be used in the

Upscaling (increased cell size):

  • Boundary : minus values above positive values above zero values;

  • Arithmetic Mean :sum cell values, excluding the NoDataValues, and divide them by the number of cells;

  • Geometric Mean : take log()-function for cell values, excluding the NoDataValues and zero values, sum cell log-values, divide them by the number of cells and take the exp()-function;

    Sum : sum cell values, excluding the NoDataValues;

    Sum Conductance : sum cell values, multiplied with the ratio of …., excluding the NoDataValues;

  • Inverse : take the inverse (1/x) of cellvalues, excluding the NoDataValues and zero values, and divide them by the number of cells;

  • Most.Freq.Occur. : take the cell value that occurs most frequently within a coarse cell, excluding the NoDataValues;

    Sum Inverse: take the sum of the inverse (x\({}^{-1}\)) of the cell values, excluding NoDataValues and zero values;

    Percentile : take the cell value that occurs for a given percentile (0-1) within a coarse cell, excluding the NoDataValues;

  • pictures/h4/image285.png

  • Block value : the value of the centre cell.

Downscale
Formulae

Downscaling (decreased cell size):

  • Arithm. Average: produces a good guess for all finer gridcells as a linear interpolation based on the coarse gridcells.

  • BlockValue: assign the value of the coarse gridcell to all finer gridcells.

Select the extent
for which the
computation apllies:

Click one of the following options:

  • Window, to force that the results of Map C will be computed for the current ZoomLevel only;

  • Map A, to force that the results of Map C will be computed for the extent of Map A.

  • • x1,y1,x2,y2, to enter the coordinates of a specific window

Compute...

Click this button to start the computation, it closes the Map Operations window afterwards.

Help …

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the Map Operations window.

Map Operation window, Special tab:

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Function

Select one of the following functions:

  • MERGE
    use this option to merge the selected IDF-files into a single one;

  • SUM
    use this option to sum all values for the selected IDF-files into a single one.

  • MEAN
    use this option to compute the mean for all values for the selected IDF-files;

  • MIN
    use this option to compute the minimum value for all values for the selected IDF-files;

  • MAX
    use this option to compute the maximum value for all values for the selected IDF-files.

IDF-files:

Select more than one IDF-file to be merged. iMOD will calculate values for the overlapping areas based on the inverse distance to the extent border of the IDF-files. The weigh-factor for an IDF-file, increases whenever the point considered, lies further away from the extent border of the IDF-file. Exact in the middle between two IDF-files, the weigh-factors for both will become 0.5.

Mask

Select this option to include a mask that determines the area to be merged, e.g. a boundary of catchment area. This option is only available whenever Function=MERGE.

Mask File:

Enter the IDF-file of the mask. All data in the IDF, not equal to the NoDataValue will be used to identify the size of the mask.


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Open IDF-file
Click this button to open an IDF-file as MaskFile.

Result:

Enter the name of the IDF-file to be created.

Compute...

Click this button to start the computation, it closes the Map Operations window afterwards.

Help ...

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the Map Operations window.

Note: It is allowed only to merge equidistant IDF-files (IEQ=0, see Section 9.5).


6.7.4IDF Edit

WHY?
IDF-files are raster files with (non)-equidistant rastersizes. Normal GIS systems can not manipulate raster files in an easy way, moreover, it is difficult to edit individual raster cells.

WHAT?
The values of individual rastercells can be easily altered by selecting the rastercells and assigning a new value using the Calculate option. Also cell sizes of existing IDFs can be altered easily by grid refinement using upscaling and downscaling techniques.

IDF Edit allows you to select particular rastercells inside an IDF-file based on a maximum of two logical expressions that optionally operate inside a polygon. Logical expressions can be carried out sequentially. Once a selection has been made, different values can be assigned to them directly, or an interpolation and/or smoothing algorithm can be applied. A selection is carried out for mid points of rastercells for a particular IDF (Selection IDF). Those midpoints will be used also to perturb corresponding raster cells for IDF-files with different rastersizes and/or position. For these cases, it should be known that not all of the rastercells are affected by the alteration due to intermediate cells that are in-between midpoints of the Selection IDF.

Methodology of selecting and calculating with IDF Edit:

pictures/h4/image28.png

HOW?
To start IDF Edit select Map from the main menu, choose IDF Options and then IDF Edit. Alternatively, you can select the menu item from the popup menu that appears when you right-click your mouse in the graphical window. In both cases, you should select at least one IDF from the iMOD Manager, the IDF Edit window will appear.

IDF Edit window, Selection tab, (left) initial window, (right) after selection:

pictures/h4/image290.png pictures/h4/image291.png

Shapes

This groupbox contains several functionalities that are needed to draw and open polygons. The functionalities are explained in detail at section Section 4.2.

Use selected IDF
to store selected
cells

Select one of the IDF-files listed in the dropdown menu. The content of the list is based on the list of IDF-files in the iMOD Manager. The dimensions of the file that you select will be used to display the selection. This file will be the Selection IDF. If you select a Selection IDF with cell sizes of 25 x 25 meter, the selection will be displayed on that dimension. It is only possible to change the Selection IDF if the current selection is cleared and/or is empty, click the Clear button to reset the selection and activate this dropdown menu again.

Select …

Click this button to start the IDF Edit Select window. In this window it is possible to select specific cells onto the selected IDF.

Example of the IDF Select window

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IDF-file:

Select one of the IDF-files listed in the dropdown menu.

Skip NoDataValue (…)

Select this checkbox to “skip” the NoDataValues in the selection. On default this will be turned on, so cells with NoDataValues will not be selected, discarding their values. For the selected IDF-file, the current NoDataValue will be displayed between brackets.

Logic

Select one of the logic variables out of the dropdown menu:
=
Equal to Value
\(<\)\(>\)
Not equal to Value
\(<\)
Less than Value
\(<\)=
Less than or equal to Value
\(>\)
Greater than Value
\(>\)=
Greater than or equal to Value
BND
Selects the cells at the boundary of an area with cells equal to Value
SPIKE(4)
selects spikes with difference byValue relative to surrounding cells in four directions
SPIKE(3)
Selects spikes with difference byValue relative to surrounding cells in at least three directions
SPIKE(2)
Selects spikes with difference byValue relative to surrounding cells in at least two directions
ALL
Selects all cells
NaN
Select values equal to a so-called NaN-value in the IDF, these numbers contains value that are beyond the range of a single precision real
Inf
Select values equal to an infinite value. E.g. infinity is caused by dividing by zero
NodataValue
Select values equal to the NodataValue of an IDF-file

Note: The selection of SPIKE(\(i\)) may be used to smooth outliers in the IDF-file using the smooth option in the IDF Edit Calculation window.

Value

Enter the value to be evaluated, e.g. 11.230 or -5.400

Include extra
statement

Select this checkbox to add an extra IDF to be evaluated for the selection. You can choose the keywords:
AND, click this option to make the selection set fulfil both the settings in Evaluate IDF A and Evaluate IDF B;
OR, click this to make the selection set fulfil at least one of the settings in Evaluate IDF A or Evaluate IDF B.

New

Select this option to start a new selection.

Add to

Select this option to add the results of the evaluation to the current selection set.

Delete from

Select this option to delete the results of the evaluation from the current selection set.

Subset

Select this option to take the result of the evaluation from the selection that is already in the selection set.

Select for Polygon

Select this checkbox to apply the evaluation inside the current polygon(s) only. This option is active whenever a shape is selected in the IDF Edit window.

553 cells selected
out of 19456

This shows the current number of selected cells 553 in the Selection IDF that consists of 19456 cells.

Clear …

Click this button to clear the entire selection for the Selection IDF. This button is only available whenever cells are selected. You will be asked whether you are sure to continue.

Get Selection

Select this button to get the selection. Each selection will be saved in the file: {USER}\TMP\{USERNAME}_TMPSELECTED{i}.DAT.


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Undo
Click this button to restore the previous selection. There will be a window to confirm this operation.

Question window:

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Zoom to Selection
Click this button to adjust the zoomlevel to the selected cells.


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Show Selection
Click this checkbox to display the selection.

Example showing (top) and deshowing (bottom) the selected cells

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Help ...

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the IDF Edit window.

Trace …

Click this button to start the IDF Edit Pipet window. The trace selection will select cells in the IDF on the basis of their value and their connection to the identified cell. In this way it is possible to select cells which are connected to each other in a particular manner.

IDF Edit Pipet window:

pictures/h6-h71/IDFEdit_pipet.png

Values should be

Choose the selection condition from the pull down list.

Search
criterium

Check one of the following options to specify how iMOD searches in 2D spatially.

pictures/h4/image293.png 5 Point
iMOD will search directly connecting cells on a five-point pattern
pictures/h4/image294.png 9 Point
iMOD will search connecting cells on a nine-point pattern.

Select
Location
on Map …
:

Click this button to start the selection. The cursor will change in a pipette. Left click your mouse to select the cell from where you want to find the connecting cells which fulfil the selection condition. The IDF Edit Pipet window will close and the number of selected cells is indicated in the IDF Edit window. Click this button again if you like to start a new selection with new criteria and cell value (shown in the message bar at the bottom of your window IDF-value:{value}).

New

Select this option to start a new selection. After a selection is made a new (clean) selection can only be started by clicking on the Select Location on Map … button. The selected cells will only than be deselected and a new selection can be made.

Add to

Select this option to add the results of the evaluation to the current selection set.

Delete From

Select this option to delete the results of the evaluation from the current selection set.

Subset

Select this option to take the result of the evaluation from the selection that is already in the selection set.

Draw …

Click this button to start the IDF Edit Draw window. Cells from the selected IDF can be selected or deselected interactively in the graphical window.

IDF Edit Draw window

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Add Cells

Click this button to add cells to the selection. Use the left mouse button and drag the cells you want to select on the graphical window. Release the left mouse button to stop drawing and click the left mouse again to add more cells to the selection.

Draw a selection in the Selection IDF:

pictures/h4/image314.png

Remove Cells

Click this button to remove current cells from the selection. Use the left mouse button to deselect cells from the current selection. Release the left mouse button to stop deselecting cells and click the right mouse button again to deselect more.

Deselect cells for the Selection IDF

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Clear …

Click this button to clear the entire selection for the Selection IDF. You will be asked whether you are sure to continue.

16147 cells
selected out of
22400

This shows the current number of selected cells (16147) in the SelectionIDF that consists of 22400 cells.

Help …

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the IDF Edit Draw window.

Clear

Click this button to clear the entire selection for the Selection IDF. This button is only available whenever cells are selected. You will be asked whether you are sure to continue.

Question window:

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Calculate …

Click this button to start the IDF Edit Calculation window. This option is not active whenever nothing is selected. First the calculation method is defined in the upper part of the window, thereafter, the IDF on which the calculation is applied is selected in the lower part of the window. Note Whenever you click the Calculation button, the IDF-file will be adjusted and the new results will be saved directly in the IDF-file. You can use the Map Value option, to inspect the adjusted results, without leaving the IDF Edit Calculation window.

IDF Edit Calculation window

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NoDataValue

Select this option to apply NoDataValues

New Value

Select this option to enter a new value. Choose one of the following options from the dropdown menu:
=
Equal
+
Add a value
-
Subtract a value
*
Multiply with a value
/
Divide by given value

Copy Values
From:

Select this option to copy the values from the selected IDF-file in the dropdown menu. The IDF-files are those that are available in the menu on theiMOD Manager.

Smooth

Select this option to smooth the values within the selection only.

Smooth options:

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Buffersize around (row/column):
Enter the number of rows/columns that need to be taken into account in the smoothing. The value 1 means that around a cell that needs to be smoothed, one row/column will be used.

Apply smoothing for following times:
Enter the number of smooth operations. The more times smoothing is done the more smoother the result will be.

Interpolate

Select one of the following options to interpolate:

BIVARIATE
Apply a bivariate interpolation. The key idea is to perform a spline interpolation first in one direction, and then again in the other direction. The interpolation is smooth.

Example of a Bivariate interpolation

pictures/h5/idfedit_calc1.png

PCG
Apply a Preconditioned Conjugate Gradient (PCG) method (linear interpolation).

Example of a PCG interpolation

pictures/h5/idfedit_calc2.png

KRIGING
Apply an Ordinary/Simple Kriging interpolation.

Example of a Ordinary Kriging interpolation

pictures/h5/idfedit_calc3.png


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Properties
Click this button to display a properties window for the selected interpolation option. Whenever the PCG is selected the PCG Settings window will be displayed (section Section 4.1), in case a Kriging method is selected, the Kriging Settings window is displayed (Section 4.1.

Table from:

Select this option to open a table (Table Display) that shows the cell values in the selected cells for the IDF-file selected in the dropdown menu (right).


pictures/h4/image326.png

Display Table
Click this button to display an overview of the cell values in a table. The IDF Edit Table window opens. The values shown in the table can be edited and will be copied to the selected output IDF file (Assign Value TO).

Example of IDF Edit Table

pictures/h4/image327.png

Colour columns …
Select this checkbox to colour the table cells by their corresponding values. Deselect this checkbox to display the table uniformly white. Each time a table value is changed, the colouring will be adjusted accordingly.

Column Width
Click this button to uniformly change the table column width by the entered column width.

Apply …
Click this button to confirm to copy the values. Be aware that you need to click the Calculate button to actually copy those values into the IDF-file selected in Assign Value TO.

Close …
Select this button to discard any entered values and to close the IDF Edit Table window.

Available
IDF-file:

Select the IDF-file that need to be adjusted from the dropdown list.

Create a New
IDF-file

Select this option to enter a different IDF file (not yet loaded in the iMOD Manager and/or to be created.


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Save As
Click on the button and enter a name for the new IDF. The name of the new IDF is displayed.

Calculate

Select this button to execute the calculation and to adjust the values in the selected IDF-file.


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UndoClick this button to undo the last calculation. Each calculation will be saved in the file: {USER}\TMP\{USERNAME}TMPCOMPUTED{i}.DAT.


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Show Selection
Click this checkbox to display the selection of the graphical window.

Help …

Click this button to start the iMOD Help Functionality.

Close …

Click this button to close the IDF Edit Calculation window. If you have adjusted one/more files, you will be asked whether you are sure to leave the IDF Edit Calculation window. Changes can not be restored once you have agreed upon closing the IDF Edit Calculation window.

Question window to leave the IDF Edit Calculation window:

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Show Selection
Click this checkbox to display the selection.


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Zoom Selection
Click this button to adjust the zoomlevel to the selected cells.

Help …

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the IDF Edit window.

IDF Edit window, GridRefinement tab:

pictures/h4/image29.png


pictures/h4/image30.png

Click this button to assign a new grid size. The Enter Value window will open.

Example of the Enter value window

pictures/h4/image31.png

Enter the new gridsize. This gridsize will be used within the selected polygon. It will be used for the entire extent of the IDF in case no polygon is selected. The new values of the gridcells are calculated by applying the up- or downscaling methodology selected in the dropdown menus.

Reshape selected IDF file

Select the IDF file from the dropdown menu.

Upscale algorithm

Select the upscaling methodology from the dropdown menu; more detail about the available methodologies is given in Section 6.7.3

Downscale
algorithm

Select the downscaling methodology from the dropdown menu; more detail about the available methodologies is given in Section 6.7.3

Resize …

Click this button to resize and save the IDF-file.

Example of a grid refinement

pictures/h4/image33.png

Note After refinement the original cell sizes of a grid might get shifted too.

Help …

Click this button to start the iMOD Help Functionality.

Close

Click this button to close the IDF Edit window.