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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
issued by query interfaces are executed by QPM based on a
moving objects model.
Buffer Management Module (BMM): Because of high cost of
insert transaction, it is difficult for the LSM to process every
requests of location insertion from QPM directly. This is the
reason why BMM exists We designed every requests
transferred from QPM into LSM through BMM. BMM do not
issue insert request to LSM immediately. Instead, it maintains a
memory buffer to gather insertion requests for a specific period,
and issue one insertion request to LSM.
put mn en — MÀ
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Location fndexing | Location Storoga
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MODE (Moving Objects Database)...
Figure 1. Overall Architecture of Moving Objects Database
Location Indexing Module (LIM): To efficiently search
moving objects with some spatio-temporal predicates, MODB
should have dedicated indexes for moving objects. LIM could
manage several indexes by the Time Segmented Indexing
method, which is newly devised in this paper.
Location Storage Module (LSM): Location information that is
reported from IAM is permanently stored into location storage
managed by LSM through the memory buffer (temporary
Storage).
Attribute Storage Module (ASM): The traditional database
systems, such as MS SQL Server or Oracle, are used to store
the attributes of moving objects without any additional efforts.
We, therefore, have no comment about ASM especially.
We will give detail explanation about cach module except IAM
and ASM in the following sections.
3. QUERY PROCESSING MODULE (QPM)
The Query Processing Module should define location data
model and location query language for the moving objects. The
location data model means data structure and operations for the
moving objects. In this paper, we revised the previous works,
and newly defined a data model, which is composed of a lot of
113
classes such as MPoint, MLineString, and MPolygon. In this
paper, we focus on MPoint.
3.1 Moving Objects Data Model
In this section, we describe class model for moving objects
components using UML. This supports time-series operations as
well as continuous moving objects operations.
(1) Data Model
Class package for moving objects components (see Figure?)
consists of four major components. ETRITime, ETRIGeometry,
and ETRIMGeometry component is a set of classes supporting
temporal operations, spatial operations, and moving objects
operations, respectively. OGISGeometry component which is
very similar to ETRIGeometry component is just included in
our package design, because we had already implemented it for
another project.
Figure 2. Class Package for Moving Objects Components
As shown in figure 3, ETRITime component has four types of
temporal classes. These classes have interfaces such as
ITemporal, ITemporalRelation, and ITmporalOperator. Each
interface consists of several operations such as figure 4.
CTRL Ea . tTemporat
Instant - PHemgoralRolsiion
"o[femgoratOperalor
a" €! — Emm n iTemporal
Terr Bon Clie > -
Period | 5 Tempera Ran
LU Femposaioceralor
"6n int 4 É ITemporat
iie Ti ip Tert a Ce -
Temporaicedéction 5 Tiemgoraiielation
Uo PCÜemeesiopirater
EC pie >
Interval VU (Üemeand
Figure 3. Temporal Classes
ITerpoeal i | ITémpsrol Duratios( Y
jl Temperal Chanel):
ITempeecikelafion | | beat recedes ( ITemporel other %
| beat Overlaps ( I Temporal other Y
| best Contains ( ITempeeat ether Y
| Bool Mowts {I Tempers! other X
4 Boe! Equakt ( ITemporal ether ):
ITemporalOperator | | beo! Interwection ( 1 Temperes ether, ret object à ptersection .
| Bool Unies. ( ITermporal other, ref object unien
| Bool Difference (ITemperal sther, ref object difference x
Figure 4. Temporal Operations
ETRIGeometry component has several geometry classes such
as Point, LineString, Polygon, GeometryCollection, Surface,
and et al. UML modeling for these classes is borrowed from
that of International Standard of Open GIS Consortium for