Geography Reference
In-Depth Information
Fig. 3.7
A datum point in the real world (CC-BY-SA 3.0 by Cosmo1976 , modified)
reference frames. In a perfectly allocentric perspective, “between the two lakes”
inherits an orientation from the locations of the two (non-oriented) lakes. “Between
dry cleaner and bakery”, an example with the same structure but oriented objects,
also inherits the orientation from the locations of dry cleaner and bakery, but is
visualized probably more like “between two locations on the street, one in front of
the dry cleaner, one in front of the bakery”.
Configurations of landmarks as alternative manifestations of a frame of reference
appear quite attractive to explain mental spatial representations as well as spatial
communication. A configuration of stationary objects spans a vector space (object-
to-object vectors), and everything else can be located within this framework in
relation to elements of the defining configuration. The configuration needs to be
updated only when changes to the objects are experienced: additions, deletions, or
modifications. Additions and deletions in the world will require adding or deleting
nodes in the representation and updating the object-to-object vector space to remain
a consistent configuration, while modifications only concern the properties stored
with a node in the configuration. Furthermore, these updates are local. They concern
only the object and its relations (vectors) to neighbored objects.
Configurations of landmarks enable only to describe locations relative to the
landmarks in the configuration, i.e., locally. For many tasks such as locomotion,
object manipulation, speed estimation and spatial updating such local frames of
reference are sufficient since they involve proximal objects. Even for tasks extending
beyond proximal objects, such as wayfinding, a global frame of reference is not
essential. A person living in a city can find their way around without knowing where
North is, or where the coast is, just by knowing the vectors of relations between the
landmarks in the configuration.
However, a globally oriented configuration can simplify wayfinding strategies.
For example, an allocentric visualization “the library is North of here” refers
to an external, global frame of reference by using a cardinal direction. The
reference provides a wayfinder with global orientation and allows applying the
least angle heuristics to North, which relieves from considering more detailed
 
 
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