Location and space: location model for fine-grained geocast

methods to realize global world model

geocast: sending messages to users in certain geographic areas
based on location model
- ex: fire warning
- need
-- target area def
-- client position def
-- comparison of client and target defs

REQUIREMENTS
hybrid location model
- geometric locations (2D and 3D geometric figs)
- symbolic locs (building, rooms, floor nos)
- combination
-- ex: GPS (geo), ActiveBadge(symbolic), ActiveBat
- mobile target areas (trains and ships)
support Q : is client w/in target A?
-supt heterogeneous addressing (symbolic, geo, or both)

APPROACH
hierarchical symbolic location model
- they tree model: what contains what
- they are using lattice-based model, so they can model overlapping models
-- path in lattice det symbolic address:


loc: /de/berlin/main street/e


...so we can have multiple paths to one location, and multiple addresses for one symbolic location

SYMBOLIC ADDRESSING
looking at intersection of target area t and client position c:
result = client inside || client outside || client nowhere
calculate probability of being in any one place
you can define threshold of probability dynamically

GEOMETRIC ADDRESSING
geometric figures desc locs

HETEROGENEOUS ADDRESSING (this is the problem!)
how do you compare symbolic to geo?
need to reduce modelling effort
- by inheritance: each floor inherits the geometry of the floor above it
[problem: he's defining for cube farms! what about non-modernist structures: blobs, inflatables, huts, tents etc]
[how does this relate to collaborative mapping spaces online: RDF? Geo-wanking?]

LOCAL COORDINATE SYSTEMS
- use nested reference systems by labelling coordinates within defs of coordinate/definitional space
- so that they can be translated

related work:
lattice-based: kainz
topological: egenhofer
hybrid locs: jiang, steenkiste