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Topographic Data Model
The LPI Topographic Data Model has been designed, recognising national standards, to support the Department's topographic data maintenance requirements. It has been developed using UML methodologies based on a target E.S.R.I. Geodatabase implementation. Thus, certain aspects of the design reflect the requirements of that technology.
The published design is a physical model and contains components required to support ongoing data maintenance activity. Topographic data delivery/distribution systems will be based on this model, essentially containing all the entities and relationships described here with minor modifications to eliminate maintenance specific data elements and to optimise the structures for query, analysis and extraction.
A full description of the data model features can be found in the Topographic Data Dictionary (PDF 620 kb).
Technical notes
- The model is made up of two components - a set of UML diagrams and an accompanying data dictionary. Both are published as HTML documents. The source model in Visio 2002 format is available on request, subject to Departmental approval.
- From the maintenance perspective, temporal (historical) requirements are managed using E.S.R.I. Geodatabase versioning technology. Geodatabase versioning is used to support optimistic locking strategies, manage transactions (including long transactions) and provide detached editing capability. As a result, complete data change histories are maintained. Thus, although not specifically referenced in the model, this functionality in itself affords compliance with the incremental update requirements defined by the ICSM Topographic Working Group.
- The model contains the following component types: abstract classes, feature classes (spatial), object classes (aspatial), relationship classes, class subtypes and attributes (mostly) controlled by fixed value domains.
- All features have a unique, persistent identifier called TopoId. This value is guaranteed unique across all Geodatabase feature classes and is assigned at instantiation, remaining unchanged throughout the life of the feature.
- All instantiated classes have unique identifier called ObjectId. This value is unique within any one class and can be considered as a primary key from the standard database declarative referential integrity perspective.
- Some feature attributes have been included in anticipation of a future requirement and availability. However it may be some time before these attributes are populated.
Further information
For further information on the model and any requests for a softcopy, please contact Alan Garside T: 02 6332 8349
Note: Softcopy is available in Visio2002 format or as a full set of HTML and associated files.
