Indices of structure at the level of the objects
Among the five indices of Table 3.1, those
of surface and perimeter are already known. Thus let us describe
the three remainders.
|
| Index of shape (SHAPE): |
|
|
pJ: perimeter (m) of the object j
aJ : surface (m2) of the object j
|
|
|
| Fractal index (FRACT): |
|
|
ln: natural log
pJ: perimeter (m) of the object j
aJ : surface (m2) of the object j
|
Interpretation: Index value varies between 1 and 2.
The more the shape of the object is complex,
the more its value approaches 2.
|
|
|
| Index of
distance to nearest neighbor of the same category / class (NEAR): |
|
|
hij: shortest distance (m)
between the limit of the object i and
that of the nearest object j of the same category
|
|
|
| Value
of the five indices of structure for the 12 objects
of the study area illustrated in Figure 3.1 |
|
|
|
Exercises on Figure 3.1 and Table 3.2
- On Figure 3.1 identify the objects:
- whose surface is respectively smallest, largest
- whose perimeter is respectively smallest, largest
- whose shape is respectively simplest, most complex
- the nearest of the same category
- Compare your visual interpretation with the value of the
indices in Table 3.2:
- which are the simplest geometrical properties,
and the most difficult to interpret?
- which is the relation between the shape index
value and that of the fractal index?
- What can one observe in connection with the index
of distance?
