FUZZEKS [to Index]
Quick start: Fuzzy kriging

The typical procedure for working with FUZZEKS

This page describes (with help of a very simple example) how to
1. prepare a data file,
2. load the data file,
3. prepare the fuzzy kriging process (and perform fuzzy kriging) and
4. view and export the fuzzy kriging result.

If you are additionally interested in aggregating parameters, you should go through this page first and then read about

1. Preparing a data file

The ASCII input data file consists of a sequence of the following sections:

More detailed information at "FDF inputfile format".

2. Loading the data file

After saving this textual information as ASCII data file (e.g. "TEST.FDF"), press F3 (or select "Load input file" from the "Project" menu) and then select this file.

As only visible result of loading an input data file (as e.g. the file that consists of the example sections above), the following contents in the management window will appear.

3. Preparing the fuzzy kriging process (and perform fuzzy kriging)

Click at the small window icon () of the left box (see the management window's contents above) in order to open a "Kriging window":

The left part of the window contains the display of the experimental variogram and the theoretical variogram. The theoretical variogram's parameters can be seen in the input fields and listboxes.
The right part of the window shows the kriging result, the corresponding listbox of display methods and some buttons to control the visible area.

The meaning of the variogram is explained in Kriging Basics / Theoretical concepts. A description of the variogram graphics is found in Handling Variograms.
The facilities to diplay the kriging result are described in Result Display Options.

The preparation of the fuzzy kriging process must be done in two steps:

The window will look a bit different to the above picture at first. You must prepare the experimental variogram (by the dialog window "Options"/"Experimental_Variogram") and enter the correct values in the input-fields at the left ("variogram") side of the window.
(For the example presented above the calculation option "Number of groups" in the dialog window "Options"/"Experimental_Variogram" has been set to 9.)
Of course, the settings depend on the actual input data.

To find a proper theoretical variogram (a variogram function - described by the parameters in the edit and listbox fields - that fits the experimental variogram) should be done with care, because its quality determines the quality of the kriging results.
A detailed description for fitting the theoretical variogram can be found on the page Theoretical variogram fitting (Function types and parameters).

If you do not use the above example data you must fix a different theoretical variogram, of course.
For simple testing purposes, where the quality of the kriging result is not important, a 100% linear theoretical variogram should do (instead of this 50% gaussian and 50% spherical theoretical variogram in the above example). This variogram type has the advantage that the kriging result is independant of range, sill and nugget effect, so the values of these parameters are always sufficient. As warning there must be said that it is not a common variogram type, it is only easy to handle!

You need not to start the kriging process; it is started automatically everytime when a recalculation is needed, which guarantees that all displayed information in the kriging window fits together anytime (the status of the calculations can be seen at the top of the screen).

4. Viewing and exporting the fuzzy kriging result

In order to get a meaningful display as shown above, some options must be changed in the dialog window "Options"/"Isolines/Dither" (in this example a difference of values between isolines of 50 and a dither factor of 10 has been chosen).

The size of the result graphics (at the right side) can be changed by the buttons at the bottom right of the window (the "all"-button usually should change it to a good size).

The lettering of the isolines can be achieved by dragging an arrow in the display with the mouse and then pressing "L" (at the intersections of isolines with the arrow an inscription is placed). The dialog window "Options"/"Lettering" can change the format and size of the numbers.

After following the above instructions the display shows isolines for the most possible values (in this case, with respect to these isolines, there is no difference between the usual crisp and fuzzy kriging results). The data points are small squares for crisp input values and small triangles for the fuzzy values (and small "u"s indicate undefined values (positions where other parameters have a value or where an "undef" has been assigned in the input data file)). The fuzziness of the result (possible deviations of the results) is displayed as density of the small dots. More detailed information at Result basics / Overview and Result Display Options / Overview, where other types of result-display are also described.

The graphical result can be exported to the clipboard by selecting "Edit"/"Copy result to clipboard", an ASCII representation can be obtained by "File"/"Krige values for raster and save to ascii-file", which needs an additional inputfile, described at Export of results .