Information Technology Reference
In-Depth Information
von Neumann neighborhood.
r
h
(
i, j
), the amount of resource
i
after this update
sub-step, is defined as:
r
h
(
i, j
)=
r
h
(
i, j
)+
r
h
(
i
+1
,j
)+
r
h
(
i−
1
,j
)+
r
h
(
i,j
+1)+
r
h
(
i,j−
1)
4
2
In other words, we can see each cell as divided in four parts, each one containing
the amount
r
h
(
i, j
)
/
4 of resource
h
, and corresponding to one of the neighbors.
The amount of resource
h
contained in each part is balanced with the corre-
sponding part of the neighbors.In case we adopt the Moore neighborhood, we
can imagine the cells as split into eight portions.The effect is that, if cell
C
(
i, j
)
is richer on resource
h
than its neighbors, part of its content will spill into them.
As mentioned before,
r
h
(
i, j
) cannot exceed the corresponding maximum value
defined for the cell (
m
h
(
i, j
)).In this case, we set
r
h
(
i, j
)=
m
h
(
i, j
).The same
rule is applied to each of the components of the seeds vector
S
(
i, j
).
2.3
The Initial Configuration
The initial configuration of the CA can be defined by the user, by setting ap-
propriate resource parameters for each cell.Also, some trees might be already
present on the territory, with all the variables defining them set.Or, the territory
might be empty, with some seeds scattered here and there (clearly, if no tree and
no seeds are present, nothing happens when the automaton is started).
3 The User Interface
The model has been implemented in C++ under Windows NT.The user interface
permits to define explicitly:
1.Different types of cell, according to the maximum amount of resources the
cell can contain and the amount of resources it produces, in order to resem-
ble the features of different types of terrain.Moreover, it also possible to
reproduce rivers (by setting high values for water content and production,
and zero maximum content values for other resources), rocky terrain (with
very low values for all the resources), roads (zero values for all the resources),
and so on;
2.Different tree species according to the amount of resources needed at each
update step, to the growth rate of the different parts, that is, how resources
are distributed among the different parts, the quantity of seeds produced;
3.The initial configuration of the automaton.
The interface shows step-by-step the evolution of the system, giving a straight-
forward image of the growth of the trees.Moreover, it is possible to show the
distribution of the resources on the territory at each step, and the overall results
of the simulation (total number of trees, trees for each species, total biomass,
biomass of each single species and single tree, and so on), as shown in Fig.1, 2,
and 3.
