Defining and Representing Temporal Objects for
Describing the Spatio-Temporal Process of Land Subdivision
Jun CHEN
Yanfen LE
National Key Lab. for Information Engineering in Surveying, Mapping and
Remote Sensing , Wuhan Technical University of Surveying and Mapping
Wuhan, China, Fax: +86-027-7884185, Tel: +86-027-7881292
Commission II, Working Group 2
KEY WORDS:
ABSTRACT
GIS, History, Model, Land Subdivision Process, Space-Time Composite
In order to model and represent the spatio-temporal process of land subdivision, the space-time composite
model proposed by Langran is extended in this paper. By defining and distinguishing temporal objects and
active objects, the geometric and thematic states of land parcels during their lifespan can be represented in
the extended space-time composite model and maintained in the land-related spatio-temporal database. The
spatio-temporal information concerning the land subdivision could therefore be referenced even after the land
parcels completed their function. In addition, time is added at attribute-level in the extended model with non-
1NF approach. Time in attribute-level can be considered at two levels; at the attribute value level and at the
tuple level.
1. INTRODUCTION
During a process of land subdivision, the geometric
components and thematic states of land parcels
evolve (or change) over time. Change of parcels in
land subdivision has two kinds: spatial and aspatial.
During spatial evolution, the geometric components
and thematic states of land parcels change. In
aspatial evolution, only the attribute values of land
parcels differ from before, while the geometric
components remain unchanged. Furthermore,
geometric change in land subdivision can be divided
into two basic types: decomposition and
consolidation. For instance, P1001 was the original
land parcel at the starting time 1949 as shown in
Fig.1. Due to land acquisition or other land
development activities, P1001 was decomposed into
smaller fragments P1002 and P1003 from 1949 to
1977. P1002 and P1003 were further decomposed
into P1004, P1005, P1006 and P1007 during the time
period from 1978 to 1983. The geometric
components of the parcels P1005 and P1007 remain
unchanged during the time period from 1984 to Tnow,
but some of their attributes assumed different values
over this period, such as the change of landuse due
to land transfer or urban development. Moreover,
P1004 and P1006 were consolidated and aggregated
into a larger parcel P1008 according to permissible
land transfer or other land-use options.
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The current and historical data of land parcel
configuration as well as land subdivision path are
useful in planning, monitoring, regulating urban
development, such as processing building
applications and tracking issued permits [Vrana,
1989; Chen,1992]. In order to maintain the land-
related spatio-temporal data and make them
accessible to users, many efforts have been made by
the academic and user communities to develop
computerized LISs with GIS technology [Price, 1989;
Langran, 1992; Guo, et. al., 1994]. However, these:
land parcel data would be maintained by the
traditional GISs as a set of snapshots which provide
a time-series view of the studied area and obscure
the individual object history of land parcels and land
transfer events [Langran, 1993a]. In addition, some
problems with the expressiveness and consistency.
of spatio-temporal topology and attribute evolution
of the land parcels remain unsolved [Edwards, 1993;
Chen, 1994]. So the spatial data models appropriate
for describing the spatio-temporal process of the
land subdivision and designing the land-related
spatio-temporal databases need to be developed.
The method of space-time composite was originally
suggested by Chrisman (1983) and was described in
detail by Langran and Chrisman (1988). In the
compositing, each change causes the changed
portion of the coverage to break from its parent
object to become a discrete object with its own
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996
