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Process Help |
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Process Name |
Menu Path |
Link to Command Table |
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VARFIT |
Command line only |
Introduction
The process allows you to display experimental variograms, as produced by the VGRAM process, and fit a model to them using interactive graphics.
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If you are going to use a Variogram Chart to either load existing VARFIT variogram models or create new variogram models from VGRAM generated experimental variograms, please see this page for more information on Rotation Parameters. |
How to use
VARFIT will also accept input from VARDIR (now obsolete) and VARHOL (now obsolete), although some of the commands will not then be applicable. You may select one or more experimental variograms from the input file to be displayed simultaneously. The variograms are displayed with different colors, line types and symbols, which you can change if you wish.
Either an isotropic or an anisotropic model can be defined, comprising a nugget variance and up to 9 individual structures. Each structure may be either spherical, power, exponential, gaussian or De Wijsian. Parameters for models comprising one, two or three structures can be moved on the screen with the mouse. Models with four or more structures are edited by entering the parameters directly.
The model parameters can be saved in the output file. They can then retrieved and edited in subsequent use of VARFIT, and can be used as input to the grade estimation process ESTIMA.
As well as displaying the variograms on the graphics screen the process also allows the variograms to be listed. Therefore all details pertaining to each variogram can be accessed interactively. This includes the lag distance, number of sample pairs, covariance and the three different types of variogram. The mean and variance of the samples is also given.
The available commands are divided into three menus:
- Variogram Fitting - this is the main menu for selecting variograms and fitting a model.
- Display Control - use this menu for customizing the graphics area.
- Plotting - this menu just includes creating and superimposing plot files.
Details of the commands in each menu are given below.
Experimental Variograms
Use "Variogram - Summary" to get a complete list of all variograms in the input file. Then select the ones you want to display using "Variogram - Add/Remove". The variograms are then added to the display list, with a legend entry for each one. You can temporarily remove a variogram using the "Variogram - Show/Hide command". Select the variogram to be removed by clicking its legend entry. Click it again to restore it.
Fitting a Model
Use the "Define New Model" command to create an initial model. You can select up to three structures which will all be spherical (type=1). If you want different variogram types then edit the model via the keyboard ("Edit Model - Keyboard"). If you want more than 3 structures then you will have to use the keyboard method for defining the model parameters. If you have 3 or less structures then you can edit the model parameters using the mouse ("Edit Model - Mouse").
Model Rotation
If you select an isotropic model then it will have the same range in all three directions, and so you do not need to define the model rotation. If you select an anisotropic model, then by default the axes of the model will lie along the coordinate axes. If you want the model axes to be rotated with respect to the coordinate system then you must use either "Model Rotation - Mouse" or "Model Rotation - Keyboard". If you use the mouse method for model rotation then one of the experimental variograms being displayed must lie along the X axis of the model. A second experimental variogram must also be displayed which lies in the XY plane of the model. Usually this will be along the Y axis of the model, but it is not compulsory for it to be so. The process will calculate the model Y axis, as lying in the XY plane, perpendicular to the X axis. The model Z axis will then be calculated perpendicular to the XY plane. The process will also calculate the angles that are needed to rotate from the coordinate system to the model system. If you use the keyboard method for model rotation then you will be prompted to enter the angles that are needed to rotate from the coordinate system to the model system.
Editing The Model
You can edit the model parameters using the keyboard or the mouse, or a combination of both. If you use the mouse method then select the parameter to be moved by clicking it with the right mouse button, and move it with the left mouse button. If you want to set one of the parameters to an exact value, then use the "Edit Model - Keyboard" command. You can do this while you are editing the model with the mouse.
Range:Sill Link
A symbol is displayed to identify the three ranges and the sill for each structure. Initially, when you select a range symbol and move it with the mouse, then the sill remains constant. However if you select "Toggle - Range:Sill Link", then moving the range symbol will also move the sill. You can toggle between the two methods while editing the model with the mouse.
Angle Definition
If you calculated your variograms using VGRAM, and you used the rotated plane option, then the variogram file will contain the azimuth and dip of each variogram in both the world coordinate system (fields WAZI and WDIP) and in the local (rotated) coordinate system (fields AZI and DIP). When the variograms are initially displayed in VARFIT the legend will be in terms of the local coordinate system. You can toggle between the two systems using the "Toggle - Angle Definition" command.
Help
Help information is available for every command. First select the Help button from the menu, and then select the command for which you require help. Selecting help on help will cancel the command.
Macros
VARFIT can be run from a macro.
If you simply want to load VARFIT from the macro and then use VARFIT interactively
you should put the command !KBON immediately before !VARFIT and !KBOFF
immediately afterwards. If you want to include VARFIT commands in the
macro then the best way is to set macro recording and run VARFIT interactively
first. The resulting macro will show you the 2 character code for each
command. You can then edit the macro if required. In fact you must replace
any single ! by [ or ]. A single ! will always occur when you terminate
the selection of variograms for the initial display. If you insert **
as a command then control will pass from macro mode to interactive use.
When you exit VARFIT, control will return to the macro. The two character
codes are also given in the file varfit.aim in the helpfile directory.
Main Menu
Information
This command gives an introduction into using the VARFIT process.
Variogram Fitting Menu
Display Control Menu
Plot Files Menu
VARIOGRAM FITTING MENU
Help
When you select the "Help" command you are immediately prompted to select the command for which you require help. Select the "Help" command again to cancel.
Redraw
Redraw the Graphics window.
Variogram - Summary
Display a summary list of all variograms in the input file to the Output window.
Variogram - List
List an experimental variogram to the Output window.
Variogram - Add/Remove
Use this command to add or remove variograms from the display list. Specify the variogram number to add it, or specify it as a negative number to remove it. Specify + to add all variograms, or - to remove all. Terminate adding or removing variograms with a !
Variogram - Show/Hide
When you add a variogram to the display list, using Add/Remove Variograms, it will automatically be displayed. If you want to hide it temporarily, but you do not want to remove it from the display list, then use the Show/Hide Variograms command. The variogram to be hidden is selected by clicking on the legend at the required variogram entry. The display for that variogram will then be hidden. Click again to restore the display.
Variogram - Remove Hidden
Variograms which are in the display list, but which are currently hidden, are annotated in white. This command removes the hidden variograms from the display list. In order to display them again at a later stage you will have to use the "Variogram - Add/Remove" command.
Variogram - Perpendicular
This command selects all variograms which are perpendicular to the reference variogram. You choose the reference variogram by clicking the appropriate legend entry with the mouse. The reference variogram and all perpendicular variograms are then displayed on the graphics screen, and are summarized in the Output window. Any variograms which were previously displayed are now hidden. You can continue to choose different reference variograms with the mouse without having to reselect the command. Choose any other command to terminate the selection of perpendicular variograms.
Define New Model
This command will define ranges
and sills for a model variogram. You can define whether you want a 1,2
or 3 structure spherical model, and whether or not you want the model
to be isotropic (same range in all 3 directions). The maximum sill is
set equal to the variance of the samples, but the values of all other
parameters are based on the extent of the graphics display, and not on
any statistical fitting method. It is simply intended to give a starting
point for you to fit the model.
You can also use this command to delete a model, so that no model is currently
defined.
Model Rotation - Mouse
When a new model is defined using the Define New Model command, the axes of the model are set parallel to the axes of the coordinate system. If your model is not parallel to the coordinate system then you must define the orientation of the model using either:
Model Rotation - Mouse
or
Model Rotation - Keyboard
The Model Rotation - Mouse command allows you to define the axes of the
model variogram by selecting the experimental variograms which lie along
the axes of the model. Therefore at least two experimental variograms
must be displayed, which are in directions that are perpendicular to each
other. The third axis will then be calculated, as it must be perpendicular
to the other two.
You must first select the experimental variogram which corresponds to the
X axis of the model. Then select either the variogram corresponding to
the Y axis, or any variogram which lies in the XY plane of the model.
If you do not select the Y axis, then it will be calculated automatically
as being 90 degrees from the X axis in the XY plane you have defined.
You select the two variograms by clicking the mouse on the legend entry
of the required variogram.
Model Rotation - Keyboard
When you use the
Define New Model command, the initial model you specify is parallel to
the axes of the coordinate system. If you want the model to be rotated
with respect to the coordinate system then you must specify the rotations.
This can be done either through the keyboard, using the "Model Rotation
- Keyboard" command, or with the mouse, using the "Model Rotation
- Mouse" command.
When using the "Model Rotation - Mouse" command you are prompted
to enter the rotation angles and the axes about which the rotations take
place.
Edit Model - Mouse
This command allows you to
change the model variogram parameters with the mouse. Select the parameter
to be changed by clicking close to the required parameter with the right
mouse button, and then select the new position with the left mouse button.
You can continue repositioning the parameter by further clicks of the
left mouse button.
If no model is defined when you select this command, then the Define New
Model command will be activated automatically. You must then reselect
the Edit Model - Mouse command to start editing the model.
You can select certain commands without leaving the "Edit Model -
Mouse" command. These include:
Redraw
Toggle - Previous Model
Toggle - (An)isotropy
Toggle - Range:Sill Link
Variogram - Show/Hide
Edit Model - Keyboard
Use the "Edit Model - Keyboard" command to round parameters to suitable values, if required.
Edit Model - Keyboard
Define a new model or edit an existing model by entering the parameters through the keyboard.
Cancel
Use this command if you wish to terminate a command which uses mouse selection from the Graphics window. For example "Edit Model - Mouse", or "Model Rotation - Mouse".
Model - Get From File
Get a model which has previously been saved in the variogram model file.
Model - Write To File
Write the current variogram model to the output model file.
Model - List Parameters
List the parameters of the current variogram model to the Output window.
Toggle - Previous Model
If the toggle is ON then when a model parameter is changed then both the new and the previous models will be displayed. All previous models will be displayed until the Redraw command is selected.
Toggle - Parameter Symbols
When you define a model, symbols will be displayed corresponding to the ranges and sills of the model. Use this command to switch the display of the symbols off and on.
Toggle - Number Of Pairs
The number of pairs of samples used for calculating the variogram value can be annotated on the graphics screen. This command switches the annotation on and off. Note that the number of sample pairs can also be found by using the Variogram - List command. Also the Minimum Number Of Pairs command can be used to remove from the display any variogram point which has less than the minimum number of sample.
Toggle - (An)isotropy
When you created the model, you created it as either isotropic (same range in all 3 directions), or anisotropic different ranges in different directions. This command allows you to switch between isotropic and anisotropic. If the model was originally isotropic, then this command will create individual ranges, although they will initially be the same. If the model was originally anisotropic then an isotropic range will be created as the average of the 3 individual ranges for each structure.
Toggle - Range;Sill Link
This toggle applies when you are editing the variogram model parameters using the mouse. Initially if you select a range as the parameter to move, then only the range moves and the sill remains fixed. The sill can be moved by selecting it and then moving it. If you toggle the range:sill link, then when you move the range, the sill will also move. Select the toggle again if you want to disconnect them.
Toggle - Angle Definition
If the variograms have been calculated using VGRAM and if a rotated plane was specified when VGRAM was run, then the input variogram file will contain the azimuth and dip of the variograms in both the world and local (rotated) coordinate systems. The "Toggle - Angle Definition" command allows you to switch between the two definitions. The azimuth and dip shown in the legend will change accordingly.
DISPLAY CONTROL MENU
Help
When you select the "Help" command you are immediately prompted to select the command for which you require help. Select the "Help" command again to cancel.
Redraw
Redraw the Graphics window.
Edit - X/Y Minimum Values
This command allows you to define the minimum values on the X and Y axes.
Edit - X/Y Maximum Values
This command allows you to define the maximum values on the X and Y axes.
Edit - X Grid Interval
This command allows you to define the spacing between grid lines on the X axis. It also lets you define the number of decimal places to be used for the annotation of the grid lines.
Edit - Y Grid Interval
This command allows you to define the spacing between grid lines on the Y axis. It also lets you define the number of decimal places to be used for the annotation of the grid lines.
Annotate - Axes
Change the annotation on the X and Y axes.
Annotate - Plot
Define a line of text and display it at any location in the data area. You may define up to 20 independent lines of text each with a maximum of 72 characters. For each line you will be prompted to define the starting point of the text using the mouse. To remove a line of text select the required line number and just press Enter at the ANNOTATION prompt.
Change Character Size
Change the character size and aspect ratio for all text displayed on the graphics screen.
Edit Variogram Attributes
Each variogram which is displayed is assigned a color, a linetype and a symbol. This option allows you to change these settings.
Select Normal/Log/Relative
The input variogram file includes the normal variogram, the lognormal variogram, the pairwise relative variogram, and the covariance. You can select the variogram to display from a menu in the Output window.
Minimum Number Of Pairs
You can select the minimum number of sample pairs to be displayed. If any variogram point has less than the minimum number, then it will not be displayed.
Default Settings
The default settings you can change are:
1 - Lines Between
Prompts
Some of the commands which write text to the Output window divide the text
into sections, with a prompt between each section. This option allows
you to define the number of lines between prompts. Enter 0 for no prompting.
2 - Pairs Annotation
Angle
The "Toggle - Number of Pairs" command annotates the number of
pairs of samples at each variogram point. You can change the angle of
the annotation; 0 is horizontal, 90 is vertically downwards, etc.
3 - Dividing Factor
You can scale the variogram values plotted on the Y axis by specifying
a dividing factor. All variogram values will be divided by this factor
prior to being displayed. If the factor is greater than 1, then the values
will be decreased; if less than 1 then the values will be increased. A
model will be fitted to the adjusted values. However if it is saved to
the output file then the true values will be written. If a model is read
from file then it will be adjusted by the factor, before being displayed.
Toggle - Autoscaling
Autoscaling is initially set ON. This means that the initial minimum values on the X & Y axes will be set to zero and the initial maximum values will be set automatically depending on the maximum X & Y values of the first variogram selected. The interval between grid lines is also set automatically.
If autoscaling is ON and you add or remove variograms, then the maximum Y value and the Y grid interval will be adjusted automatically to fit the variograms. The maximum X value and the X grid interval will not be changed. If autoscaling is ON then the minimum X and Y values will always be set to zero.
If you toggle autoscaling OFF then the current X & Y minimum and maximum values and grid intervals will be maintained irrespective of variograms which may be added to or removed from the display. To change the values you must either reset them using the individual Edit commands or toggle autoscaling back ON.
Note that the maximum value on the X axis is set according to the maximum value of the first variogram displayed. Toggling autoscaling ON or OFF will not affect the maximum X value or the X grid interval. The only way to change these two values is to use the individual Edit commands to reset them.
Toggle - Background Colour
The initial display has a black data area, with a grey background. You can toggle between a grey and a black background using the Toggle - Background Colour command.
Toggle - Bell
Some commands include a bell to draw your attention to information displayed on the Output screen. The "Toggle - Bell" command allows you switch the bell on or off.
Toggle - Grid Type
A full grid is displayed on the initial screen. You can toggle between the full grid and tick marks using the Toggle - Grid Type command.
Toggle - Legend Display
Switch the legend display on or off.
Toggle - Legend Header
The legend header is a single line of text located immediately above the legend. This commands allows you to switch the display of the legend header on and off.
Toggle - Normalise
The Normalize toggle allows you to normalize the displayed variogram(s). This means that all variogram values are divided by the variance, so that the sill is set to 1. This is particularly useful when comparing variograms from different rock types or different cutoffs for indicator variograms.
Toggle - Symbol Display
A symbol is plotted at each point on the experimental variogram. This command allows you to switch the display of symbols on or off.
Toggle - Text Display
The initial Graphics window includes a text area in which the variogram model parameters are displayed, if defined. The position of the origin of the data area is controlled by the environment variable DATA_AREA which is usually defined in the aim file VARFIT.AIM. The aim file should also include an environment variable DATA_AREA_NOTEXT which defines an alternative layout which does not include the text area. You can swap between the two layouts using the Toggle - Text Display command.
Toggle - Variance
If you toggle the variance ON, then a horizontal line will be displayed showing the variance of the samples. The default is OFF, so the line will not be plotted.
Toggle - Symbol Display
Run Macro
This option allows
you to run a sequence of commands which had previously been saved in a
text file.
The best way of writing a macro is to switch macro recording on before
you enter VARFIT. Then use the commands which you want to store in the
macro, so that the command names and responses are saved to the file.
Exit from VARFIT, and switch macro recording off. Edit the text file in
your system editor. Remove the !START, the call to !VARFIT, the EX (exit)
command, !END, and any of the VARFIT commands which you do not want included.
Then reenter VARFIT and use the "Run Macro" command.
PLOT FILES MENU
Help
When you select the "Help" command you are immediately prompted to select the command for which you require help. Select the "Help" command again to cancel.
Redraw
Redraw the Graphics window.
Create Plot File
The current graphics display will be saved in a database file. A grey border, if displayed on the screen, will not be included in the plot file.
Superimpose Plot File
Superimpose an existing plot file on the graphics window.
Exit
Exit from the variogram fitting process.
Files, Fields and Parameters
Input Files
|
Name |
Description |
I/O Status |
Required |
Type |
|
IN |
File containing experimental variogram[s]. This will usually be created by VGRAM. The file can contain up to 500 variograms. |
Input |
Yes |
Variogram |
Output Files
|
Name |
I/O Status |
Required |
Type |
Description |
|
OUT |
Output |
Yes |
Undefined |
Input and output file for parameters of fitted models. The file contains one record per model. If the file already exists and contains all the required fields [53 fields in total] then any existing models will be maintained, otherwise the file will be deleted and a new one created. The new file will contain the following fields: VREFNUM - variogram reference number VANGLE1 - first rotation angle VAXIS1 - first rotation axis VANGLE2 - second rotation angle VAXIS2 - second rotation axis VANGLE3 - third rotation angle VAXIS3 - third rotation axis NUGGET - nugget variance ST1 - model type for structure 1 [1=spherical, 2=power, 3=exponential, 4=gaussian, 5= De Wijsian] ST1PAR1 - parameter 1 for structure 1 ST1PAR2 - parameter 2 for structure 1 ST1PAR3 - parameter 3 for structure 1 ST1PAR4 - parameter 4 for structure 1 ST9 - model type for structure 9 ST9PAR1 - parameter 1 for structure 9 ST9PAR2 - parameter 2 for structure 9 ST9PAR3 - parameter 3 for structure 9 ST9PAR4 - parameter 4 for structure 9 |
Fields
|
Name |
Description |
Source |
Required |
Type |
Default |
|
AVE.DIST |
The field to be plotted along the X axis. Usually either LAG or AVE.DIST. The default is AVE.DIST. |
IN |
No |
Numeric |
AVE.DIST |
|
VGRAM |
The field to be plotted along the Y axis. Processes VARDIR and VARHOL create fields V.GRAM, REL.VGRM and LOGVGRM. Process VGRAM creates fields VGRAM, PWRVGRAM and LOGVGRAM. The default is VGRAM. |
IN |
No |
Numeric |
VGRAM |
|
KEY |
If the IN file was created using VGRAM and a KEY field was used, then the name of the KEY field should be specified here. |
IN |
No |
Any |
Undefined |
|
AZI |
Field containing azimuth of experimental variogram. Processes VARDIR and VARHOL create field DIRECTN, and VGRAM creates field AZI. The default is AZI. |
IN |
No |
Undefined |
AZI |
|
DIP |
Field containing dip of experimental variogram. Usually DIP, the default. |
IN |
No |
Numeric |
DIP |
