Fuzzy Logic
Arc-SDM uses a fuzzy logic "calculator" to combine evidential themes using the fuzzy operators described in the section discussing the fuzzy logic method (fl1.pdf). Each of the "calculations" or operations is recorded in a dBase file that then can be viewed, rerun and/or plotted at any point in time.
To combine two or more themes using a fuzzy operator:
Select 'Fuzzy Logic...' from the SDM menu.
You are first prompted to select
an existing fuzzy logic model file (.dbf).
To... |
|
...append a record of the operations to be done in this session to an existintg file (created during a previous session): | select the file and click 'OK'. |
...create a new file: |
|
Then the "fuzzy logic calculator" dialog is displayed:
The listbox contains all of the theme-field pairs from the active view for which the values in the field or grid cells falls in the range [0,1]. In the case of a floating point grid theme, the "field" is identified as 'Value'.
Select a
theme-field pair by clicking it in the listbox display.
Select one or more additional theme-field pairs by
holding down the shift-key and clicking them. NOTE:
Two fields from the same theme attribute table
cannot be selected at the same time.
When two or more theme-field pairs are selected, the
'Calculate' button becomes active.
The default filename for the output grid from a fuzzy ... |
... operation is ... |
AND | And<#> |
OR | Or<#> |
SUM | Sum<#> |
PRODUCT | Prd<#> |
GAMMA | Gamma<#> |
The new theme will be added to the active view and to the top of the theme-field list in the dialog box for input to a subsequent operation.
To view the contents of the fuzzy logic model
This displays the contents of the file as in the following example:
NOTE: The functions run from the 'Plot' and 'Run' buttons are described in the next section, 'Process Existing Model'.
To Select another model file
At any point you can click the button labelled 'Select Model File...' to select another file. Subsequent operations will be appended to the newly selected file until the dialog is closed or another file is selected.
Next | Section Contents | Home |