Growth rules
SLEUTH begins with a set of initial conditions which is the input data configuration of the landscape. A set of decision, or growth, rules is then applied to the data to simulate urban driven land cover change.

Definition of Urban Growth Dynamics
In this section we first discuss the different growth steps and the functional form of their dynamics, and then depict an example of the growth step followed by the pseudo code that defines this step. Two measures of suitability affect the likelihood of urbanization throughout the growth process. The suitability is defined by an exclusion layer (for example, water, swamps, etc.) and by slope. Slope above 21% cannot be urbanized. Given that the local slope (slope (i,j)) is below 22%, the slope_coefficient determines the weight of the probability that the location (i,j) may be built upon.

The urban growth dynamic implemented in the Urban Growth Model (UGM) component of SLEUTH is defined through four steps:
(i) Spontaneous Growth
(ii) New Spreading Centers
(iii) Edge Growth
(iv) Road-Influenced Growth

A growth cycle consists of these four steps and, if modeling land cover, the deltatron change dynamics.