Database Reference
In-Depth Information
because all the end user needs to do is execute a query for watercourse further con-
strained by some physical measure of length or width. Merea Maps does one further
thing to help end users; the term
watercourse
is itself less used than either river or
stream, so Merea Maps provides an alternate label for watercourse—“Rivers and
Streams”—that makes it clear what is meant and enables queries to be entered that
use this term as well as watercourse.
10.4.6.2 Uncertain Boundaries: Places and Postcodes
There are many features that either have well-defined boundaries that are not gener-
ally known or do not have well-defined boundaries at all. Features such as hospitals
and universities will have very well-defined legal boundaries, but these boundaries
may not be well known and in many cases will not be clearly delimited by boundary
fencing. Conversely, areas such as localities within cities and postcodes in Merea
do not have defined boundaries. Historically, the GI community has always been
uncomfortable with these features and often attempts to impose hard boundaries on
them. First, let us consider the case of a large Hospital, Medina and North Merea
General Hospital, shown in Figure 10.7. It exists on one site but extends across a
main road and has no physical boundary. The Hospital does have a well-defined legal
boundary, but this includes a row of houses and shops that were bequeathed to the
Hospital and are used by the Hospital to generate additional income. Even though
these premises are therefore technically part of the Hospital, operationally they
are not really related at all, and indeed most Mereans, including Hospital staff, are
unaware that they are associated with the Hospital. So while the legal boundary is
well defined, its definition covers more than we would think of as being the Hospital.
Merea Maps could attempt to generate an “operational boundary” that would
only enclose the land associated with the health care aspects of the Hospital estate.
Main Hospital
Car park
Shops
Housing
Legal Boundary
Medical buildings
FIGURE 10.7
Hospital with no well-defined physical boundary.
