Communication Aspects: How Landmarks Enrich the Communication Between Human and Machine - Landmarks: GIScience for Intelligent Services - page 174

('Have a nice day') [ 1 , 15 , 18 , 49 ] . In each phase, each communication partner has
different tasks, and both need to produce and understand references to landmarks.
In human-computer interaction there is, of course, no need for social
conventions—the computer will always behave the same way. In the following
we will assume that the human user requests some spatial information (location of
a geographic object, or route directions) from the computer. We also assume that
the context is defined, i.e., we do not assume a general purpose query machine, but
some service dedicated to spatial communication, for example, a navigation service.
The requirements for a computer to produce landmark references have been
discussed throughout Chaps. 4 and 5 . They can be summarized as follows:
1. A data set (or the combination of several data sets) about a geographic environ-
ment that contains data which makes geographic objects discriminable from each
other and allows to access (some of) their properties (such as location, size, or
type).
2. A data structure that allows for capturing the landmarkness of geographic objects
and for integrating this information into other required data (e.g., a path network
for routing purposes).
3. A mechanism to establish an object's principle suitability as a landmark—its
salience .
4. A mechanism to establish an object's suitability in a specific given situation—its
relevance .
To make landmark production work it needs the actual communication mecha-
nism(s), i.e., some way to communicate the chosen landmark reference(s) to the
human user in verbal or graphical form in the right context.
In short, the production of landmark references by a computational system
seems to be a reasonable expectation. However, people may have differing previous
knowledge about an environment and, thus, require different detail in the spatial
descriptions. Or they may have some clarification questions (in a securing phase)
and the system would need to understand and come up with alternative or more
detailed descriptions.
Understanding landmark references is the greater challenge compared to produc-
ing them. Accordingly, the requirements for successfully understanding landmarks
may be greater as well. At least they appear to be less well defined. The minimal
requirements are:
5. A mechanism to parse human queries (verbal or graphical) into a form that the
computer can process.
6. A data repository that allows for a matching of landmark references to geographic
objects—something like georeferencing [ 36 ] , only that the references can be
expected to be less well specified than in an authoritative gazetteer.
7. Some (spatial) reasoning mechanisms to correctly relate all references in the
query, which then allows to come up with a reasonable answer—bringing us
back to producing landmark references.