
LUC : Reference Manual
Scenario editor, modifying rulesThe a priori transition probabilities from the basic transition matrix can be modified by a set of RULES one set for each possible transition, that can modify the a priori probabilities using a set of operators that use spatial and temporal aggregate and neighborhood properties to modify the transition probabilities.A special case of the spatial constraints or driving forces are of course global properties of the area considered. Other rules can be based on any attribute or property a given spatial unit has such as soil, geology and terrain features, climatic variables, infrastructure, and population, available in auxiliary matrices parallel to the initial lanuse matrix. RulesRULES are expressed as first order production rules:IF condition AND/OR condition THEN probability(n,m) CHANGEOPERATOR VALUEwhere
CHANGEOPERATORs are:
Please note: REL* functions modify the current probability in RELATIVE terms: Probability is the a priori transition probability from class n to class m;
VALUE: degree of change, e.g., 500o/oo, or 100o/oo
Operators and functionsthe following functions are used:
Rule examplesIF FRACTION(1.1,1) > 500 THEN P(1.1) REINCREASE 500IF more than half the immediate neighbours of a cell are city (1.1), then the probability of transition to city increases by 50%; please note that the same principle of contagion can be expressed differently as well: IF FRACTION(1.1,1) < 100 THEN P(1.1) RELDECREASE 950with somewhat different behaviour. IF FRACTION(1.1,2) > 950 THEN P(1.1) RELDECREASE 900IF more than 95% of the neighbours in a 5x5 area around a cell (all but 2 ?) are already city, decrease the probability of transition of the last cells into city.
 
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