Database Reference
In-Depth Information
Woody Ve getation
Trees
Scrub
Ve getation
Grass
Herbaceous
Ve getation
Crop
Salt Water
Water
Fresh Water
Metalling
Made Cover
Building
Sealed Cover
Rock
Compacted
Sand
Porous Cover
Soil
FIGURE 10.9
Landcover classes.
the production of traditional cartographic maps, enabling areas such as woodland
and marsh to be clearly shown and differentiated on mapping. Most existing hierar-
chies can be a bit confused in places, often mixing land cover with land use—terms
that, although related, are clearly different; the former deals with what is on the
surface and the second how the land is used. But, there is also confusion between
what something is—the type or class of a Feature—and what is
on
it or part of it.
For example, a typical land cover class is Woodland, but is this not really a type of
Feature? Strictly, from a land cover perspective, the cover is trees, not woodland,
but in common parlance people have conflated the two such that it would not seem
odd to many people that woodland was considered to be a land cover class. What is
certainly true is that what makes something a woodland are the trees that cover the
land—trees can be seen as a part of woodland just as buildings can be seen as being
part of a hospital or school. These observations enable Merea Maps to do two things;
first, it is able develop a land cover ontology that is more truly about land cover, and
it is then able to use this land cover ontology to help define its topographical ontology
(Figure 10.9).
If Merea Maps were focused exclusively on topographic definitions, then it could
get away with just incorporating land cover aspects into its Topographic Ontology.
Merea Maps, though, decides that if it produces a separate Land Cover Ontology
that is then reused by the Topographic Ontology, this will provide its end users
with greater flexibility. This decision also reflects the difference between the upper
levels and purposes of the two ontologies. The Topographic Ontology is more con-
cerned with differentiating classes on broad topographic groups such as settlements,
