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Metadata and Geographical Information Systems Adrian Moss KINDS project, Manchester Metropolitan University, UK

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Presentation on theme: "Metadata and Geographical Information Systems Adrian Moss KINDS project, Manchester Metropolitan University, UK"— Presentation transcript:

1 Metadata and Geographical Information Systems Adrian Moss KINDS project, Manchester Metropolitan University, UK a.moss@mmu.ac.uk

2 The need for metadata As computing power becomes comparatively cheaper and mass storage space increases data increases in value. A method of cataloguing and managing data is needed.

3 Uses of metadata n to maintain an organisation's internal investment in geospatial data, n to provide information about an organization's data holdings to data catalogues, clearinghouses, and brokerages n to provide information needed to process and interpret data to be received through a transfer from an external source

4 Visions n The Digital Earth: Understanding our planet in the 21st Century by Al Gore The Digital Earth: Understanding our planet in the 21st Century n Microsoft "Digital Nervous System" by Bill Gates Microsoft "Digital Nervous System" n Although often such ‘visions’ do not explicitly mention metadata, yet it will be key to their development

5 Defining geospatial metadata A metadata record is a "surrogate" record which describes another information resource. It can also be called "data about data". The US Federal Geographic Data Committee, (FGDC), define metadata as describing: availability -- data needed to determine the sets of data that exist for a geographic location. fitness for use -- data needed to determine if a set of data meets a specific need. access -- data needed to acquire an identified set of data. transfer -- data needed to process and use a set of data. (Source: FGDC Content Standard for Digital Geospatial Metadata, CSDGM).

6 Applications for geo-spatial metadata Finding spatial data Transferring data from one system to another Requesting a service from another computer

7 Types of metadata (1) n Collection level metadata –Content Overview of the contents of a data collection –Purpose Identifying potential data sources

8 Types of metadata (2) n Data set level –Content Description of the content of a data set –Purpose Evaluating the usefulness of data

9 Types of metadata (3) n Feature level –Content Detailed description of data and features –Purpose Interoperating Open Systems

10 Metadata formats: Example 1 The Dublin Core n Widely used to describe ‘document like objects’ n Consists of 12 elements all of which are optional and may be duplicated –Title, Author, Publisher, OtherAgent, Date, ObjectType, Form, Identifier, Relation, Source, Language, Coverage n Highly flexible, but consequent lack of semantic and syntactic precision

11 Metadata formats: Example 2 The Content Standard for Geospatial Metadata n Data set level metadata. Developed by US Federal Geographic Data Committee n Detailed, extensive record system including: Overview Organization of the Standard 0 Metadata 1 Identification Information 2 Data Quality Information 3 Spatial Data Organization Information 4 Spatial Reference Information 5 Entity and Attribute Information 6 Distribution Information 7 Metadata Reference Information 8 Citation Information 9 Time Period Information 10 Contact Information OverviewOrganization of the Standard0 Metadata1 Identification Information2 Data Quality Information 3 Spatial Data Organization Information4 Spatial Reference Information5 Entity and Attribute Information6 Distribution Information7 Metadata Reference Information8 Citation Information9 Time Period Information10 Contact Information

12 Review question 1

13 Components of a metadata system n Metadata format –The metadata implementation chosen as the basis for the system n Creation tools –Any automated methods of generating data n Transports –Methods for querying and transporting metadata in a networked environment

14 Metadata in resource discovery systems n Used to increase the accuracy of resource discovery queries –Controlled vocabularies –Thesauri –Gazetteers

15 Controlled vocabularies n Defines words a terms that maybe used when cataloguing records –e.g.. Use river not stream n Often requires data to be catalogued by an expert librarian

16 Thesauri and dictionaries n Define relationships between terms

17 Gazetteers n Links place names to spatial locations n KINDS Gazetteer (http://midas.ac.uk/kinds) extends thesaurus relationships to describe relationships between spatial units

18 KINDS Gazetteer relationships

19 Metadata creation tools n Creation tools are used to automate the creation of metadata n The requirement for creation tools increases as the level of detail in a metadata format increases

20 Finding data across data sets n In a distributed environment data and metadata will be held on different servers. –Z39.50 protocol allows searching of data resources held on different servers n Also metadata can be embedded in data objects. –Embedding metadata in web pages –XML, eXtensible Markup Language

21 Z39.50 - a protocol for querying multiple index servers A Z39.50 compliant client accepts a request and distributes it to multiple metadata index servers. The results are collated by the client and returned to the user as a single output Client Servers

22 Embedding metadata within web pages/data Metadata description of page Hyper-text lay out of page Catalogued by search index

23 XML - Extend the internet XML eXtensible Markup Language permits definition of custom ‘tags’ for specific purposes. E.g. to describe the extent of a geographic data set. Enables direct communication of metadata between networked applications

24 The future of metadata in resource discovery systems n Multiple metadata formats –The Warwick Framework n From static to dynamic surrogates –Automatic generation of metadata based upon the users requirement

25 The Warwick Framework n A proposal to develop ‘packages’ of data which include: the data it self and one or more metadata descriptions of the data. n Response to the problem that no single metadata format is suitable for many requirements

26 Metadata and GIS support n Using GIS is a knowledge intensive activity. Users must learn the concepts associated with GIS and mapping, as well as how to work the GIS package itself. Often these tasks are complex and time consuming. GIS can be made much simpler to use if certain low level tasks could be devolved to the GIS package or if the GIS could provide advice to the user on best practice. n Plewe and Johnson (1997) report a system which reads metadata files and advises the user of quality issues associated with the data set being used.

27 Review exercise 2

28 Metadata and Open GIS (1) n Aims: –Transferring data from one system to another (support with appropriate reformatting, or on-the-fly access to open systems based data bases) –Requesting services from networked servers n Led by Open GIS Consortium (http://www.opengis.org)

29 Metadata and Open GIS (2) n Open GIS data structures created n BUT, more serious intellectual problems standardising geographical world views. Characterised by a lack of “global schemas”.

30 Conclusions n Metadata being rapidly developed by information scientists for resource discovery. –Dublin Core is becoming standard for “document like objects”. DC support spatial and temporal fields. n Little formal support for metadata in commercial GIS software. n Open GIS has achieved technical success but standardisation of world views will be harder.

31 Control questions


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