providing methods for the capture and analysis of dynamic phenomena through a postgresql extension

Providing methods for the capture and analysis ofdynamic phenomena through a PostgreSQL extension

Peter Broßeit

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Is the time still an issue in geoinformatics?

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Capabilities for spatio-temporal analyses in today‘s GIS are at best vestigialData storage through existing data types –> No unified modelling in the time dimension

Where and when did the most tornados happen during the

last 10 years in Europe?

Which land use features are the predecessors of a particular nature reserve?

Are there temporal overlappings between

various data sets or features?

Is the time still an issue in geoinformatics?

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Concept

• Modelling the valid time dimension withone user defined data type

• Instants, periods of time and temporal complexes• Based on ISO19108

Actual Purpose:

Unified modelling -> homogeneous queriesExplicit modelling of periods of time and temporal complexes

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Temporal Schema - ISO19108

Schema to describe the temporal characteristics of geographic information

Feature attributes, feature operations & feature associations

• Temporal objects• Various reference systems• Combination with features

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The Temporal Objects

TM_Primitive

ISO19108

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The Temporal Objects

MultiPrimitive

TM_Primitive

ISO19108

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The Temporal Objects

TemporalPositionISO19108

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The Temporal Objects

TemporalPositionISO19108

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The Temporal Objects

Only one internal system

TemporalPositionISO19108

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Textual Representation

• Necessary for the information exchange-> The user’s view on the database level

• Some terms are set by the Temporal Schema (ISO19108)

The concerning standardisation does not go far enough-> Requires arbitrary specifications-> Only restrictedly suitable for a general information exchange

Actually needed: WKT for time

?

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Operations

Basic functionsOperating only in the time dimensione.g. Simple queries, Boolean operations, ISO19108-Functions

Spatio-temporal analysisIntegrated processing in the spatial and temporal dimensione.g. ISO19108-Feature Successions

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Relative Position

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ISO19108 – Feature Successions

Feature SubstitutionFeature DivisionFeature Fusion

May be derived trough a combined use of temporal and spatial operations

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Why PostgreSQL?

Standard compliance and far-reaching possibilities in configurationSpatial functionality provided by PostGIS -> OGC compliant

Implementation with PostgreSQL

User defined base type in PostgreSQL

Current capabilities:The six object typesExemplary the three types of reference frameVarious basic functionsExamples for spatio-temporal analysis

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What are the predecessor and successor associations between several countries?

Shapefile: WEIDEMANN, N. B.; DOREEN, K.; GLEDITSCH, K. S. (2010): The Geography of the International System: The CShapes Dataset, http://nils.weidmann.ws/projects/cshapes/shapefile (2013-03-07).

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For each time step: In which state did the most tornados take place?

Shapefile: NATIONALATLAS.GOV (2011): nationalatlas.gov – Map Layers, http://nationalatlas.gov/maplayers.html (2013-03-07).

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Perspective

Purpose: From the proof-of-concept to the first release

• Extend the range of functions• Decent documentation• Extensive testing• Validation of the concept

Particular:

Managing the various reference framesSyntax for the information exchangeUser defined reference frames

Documentation with Doxygen

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Peter BroßeitPeter.Brosseit@mailbox.tu-dresden.de

Masters programme ‚Geoinformation Technologies‘