1 Spatial Modelling of the Terrestrial Environment - Georeferencial

214 Spatial Modelling of the Terrestrial Environment
Road
Built
Open
Space Tree Water Road Built
Open
Space Tree Water
Level 1
6 71 165 14 14
3 0 28 2 0
2 83 1363 44 87 9
2 83 1363 44 87 9
Level 2
0 1365 83 44 96
0 1 24 2 2
Level 3
1181 1 1 2 2 13 1
0 1181 4 2 14
1181 1 1 2 2 13 1
0 2 0 0 0
2
2
Level 4
0 0 2 0 0
0 0 0 0 0
Figure 10.7 Two graph visualizations of the containment hierarchy for the land-cover nodes
(regions) in Figure 10.5. The left-hand panel expresses the containment hierarchy in terms of
N ∈ XRAG and the right-hand panel in terms of N ∈ r containment . See text for details
It may be possible, therefore, to exploit this containment hierarchy to perform an analysis
of built form as a function of land use.
A depth-first graph-searching algorithm (Sedgewick, 1990), implemented in SAMS, is
used to examine the containment hierarchy for the graph (study area) as a whole. Figure 10.7
presents a visualization of this hierarchy in terms of both N ∈ XRAG (left-hand panel) and
N ∈ r containment (right-hand panel). Level 1 in the hierarchy indicates those nodes (parcels)
of each land-cover type that are not contained within any other node (parcel) in the study
area. Level 2 nodes are wholly contained within a Level 1 node, Level 3 nodes are wholly
contained within a Level 2 node, and so on. The values in the circles indicate the number
of nodes of each land-cover type at the given level. Thus, for example, there is a total
of 165 OPEN SPACE nodes at Level 1 (left-hand panel; N ∈ XRAG), of which 28 contain
nodes from Level 2 in the hierarchy (right-hand panel; N ∈ r containment ). Figure 10.7 also
shows that these 28 nodes contain 1363 of the total 1365 Level 2 BUILT nodes (i.e., OPEN
SPACE 1363
→ BUILT).
Figure 10.7 indicates that the Orpington scene is only partly characterized by the
hypothesized ROAD→OPEN SPACE→BUILT containment hierarchy (i.e., ROAD→OPEN
83
SPACE 1181
→ BUILT at Levels 1 to 3). There is also a strong containment hierarchy in terms
of OPEN SPACE and BUILT at Levels 1 and 2 (i.e., OPEN SPACE 1363
→ BUILT), accounting for