CREATING AND PUBLISHING METADATA
VeronikaWeignerová – Antal Guszlev
NYME GEO Térinformatika Tanszék ESRI research fellow
ÖSSZEFOGLALÁS ABSTRACT A metaadat egyszerűen adat az adatokról. A
metaadat segít az adatok kezelésében, és lehetőséget ad az információkhoz szükséges adatok gyors megszerzésére. A Geoinformatikai karon nagy mennyiségű
földrajzi adat áll rendelkezésre, amelyet oktatási és kutatási munkák során használunk. A rendszert úgy alakítottuk ki, hogy az adatok egyszerűen hozzáférhetőek legyenek, és a kar honlapján is publikáljuk. A http://www.geo.info.hu/~ga/metaadat/ internet címen bárki elérheti a folyamatosan frissített adatbázist.
About metadata we can easy say that it is data about data. Metadata helps us to maintain our data and enables to get right data in right time for our information services. The College of Geoinformatics uses large amount of spatial data for educational and research purposes. Such data must be stored, and should be accessible and searchable in easy, friendly way. For that reason we have established the database of GIS data. Furthermore we continuously create metadata information that is accessible on department website
http://www.geo.info.hu/~ga/metaadat/. Step by step we plan to declassify all list of data and its metadata on the mentioned website.
1.
DATABASE
During years large amount of geographical data has been cumulated at the College of Geoinformatics. Data is used for educational and research purposes. Students as well as their tutors need to have easy access to available data and to information about that data. The well-ordered and structured GIS database enriched by metadata can solve the problem. Furthermore, publishing list of data and its metadata on Internet assures about accessibility for everyone.
The first question, related to database, is the data structure. There are several logical possibilities of data structuring in case of geographical data, as the main purpose is to find queried information very fast and without any obstacles. In our case, the first suitable structure is geographical one. We can organize data according to its
cartographical point of view. Some data contains different geographical information and it is better to distinguish them in that way. For example, digital topographical maps were sorted by scale. Further, the topographic maps on same scale were subdivided regarding the number of individual mapsheet. Other potential structures consider location of data, publisher or source of data. Considering large number of data and its enormous variability we were not able to use only one specific type of structure, on contrary, we needed to use different possibilities in our database agreeably to given applicability. Another given example presents data located in area of Velence Lake that is the area of research interest at the College of Geoinformatics. Such data were gleaned together and structured regarding its geographic specialization.
Before entering data into the database, we always consider it very important to verify data correctness and spatial accuracy. Then we try to obtain as much information about data as possible. That information we glean in metadata file. Metadata issues will be described hereinafter.
As the majority of our data is available and handled in ArcGIS environment, for database creation we have decided to use the ArcCatalog application that belongs to ArcGIS Desktop. With ArcCatalog we can easily browse several types of spatial data, see its preview in table as well as geographic form of view, and manage metadata.
2.
METADATA
The most important part of our work relates to creating data about data, which is how we can call metadata informally. Nowadays metadata is inseparable part of any data. It provides us lot of useful information as will be presented in following lines.
The first questions, which we should answer, what metadata exactly is, and why it is so useful for us. Referring to (ESRI, 2002), metadata is a summary document providing content, quality, type, creation, and spatial information about a data set. A big advantage of metadata is its small size that enables easy handling with its file. Metadata can be stored in any format such as a text file, Extensible Markup Language (XML), or database record. We use metadata, because it facilitates work with spatial data. It enables us to get all needful information about required data as its correctness, accuracy, location, author, accessibility and constraints. Moreover it also helps to avoid duplication of data. With metadata that fulfils given standards we can be perfectly assured about suitability of related data for our purposes.
Copyright and licensing issues are of great concern to the Hungarian GIS community. By publishing metadata we can supply the information need of the users, without actually publishing the dataset. In the description everybody can check if he/she has the right to access a file and see if there are any restrictions regarding its usage. Most of our current data sources are marked “educational purposes only”.
Information gathered by metadata can be divided into several types. The identification section contains main information about data including citation, source of data, and date of creating, keywords, or access constraints. Next section relates to spatial reference with information about geographical coordinates and projection. The distribution part informs about possibility how to get data, whether it is downloadable, or if it must be ordered from publisher, and also information about format and price. The attribute section specifies entity type and its characteristics. Information about metadata itself, as who created them, when and where, belongs to metadata reference part. Finally there is also information about spatial data organisation and data quality. Some of the information are mandatory for metadata service including a title, publisher, spatial extent, theme and type of resource, and have to be filled in the file before publishing. In ArcCatalog that we use for metadata creation, some data, as for example spatial extent and coordinate system, are supplied automatically.
We use ArcCatalog application for metadata creation and editing. We save metadata in XML format according to ESRI proprietary standards, and than also export it to HTML format. HTML files are used for publication on metadata website. Our purpose to publish metadata requires following given content standards. Metadata standards are defined by official standards organizations. An important standard in USA is the FGDC Content standard for digital geospatial metadata, first published in 1998. The International Organization for Standardization has also created a spatial metadata standard. ArcCatalog provides a metadata editor for both standards. ESRI software uses the XML standard for metadata processing, (ESRI, 2002).
3.
METADATA WEBSITE
The list of available geographical data and also created metadata should be easily accessible for students, tutors or even public interested in such information. For that reason we have created the Metadata website, where students can find data that suits their needs. The website gives an overview on geographical data available at the College of Geoinformatics. The URL address is http://www.geo.info.hu/~ga/metaadat/.
At this moment a pilot version is available. The website provides information that contains definition of metadata, the list of up to now processed data and its metadata, information about main data providers and links to their own websites.
There are several ways of publishing geographical data on the Internet, and we have considered many of them. We have chosen a sophisticated client side technology, based on SVG (Scalable Vector Graphics), which is an XML-based structured language for describing two-dimensional graphics and graphical applications. The MapViewSVG application enables us to publish data directly form ArcMap. The resulting site can then be customized to better suit the users’ needs. In order to view the page, the users are required to have an SVG viewer plug-in, which is already installed on most of the computers. For those who don’t have it, there is a possibility to download the latest viewer application.
4.
FUTURE PLANS
The created website should mainly serve the students and their tutors. We plan to complete the list of geographical data available at the College of Geoinformatics that is nowadays substituted by pilot list of data. All data has to contain attached metadata that corresponds to given standards. The website will be regularly updated and enlarged. As the database will grow, advanced search functions will have to be facilitated.
References:
1. Metadata and GIS. An ESRI White Paper. ESRI, October 2002. 2. M.-J. Kraak – A. Brown: Web Cartography, Taylor & Francis 2001
3. Federal Geographic Data Committee: Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998), http://www.fgdc.gov/metadata/metadata.html 4. Scalable Vector Graphics, http://www.w3.org/Graphics/SVG/
CÍM
Veronika Weignerová
Nyugat-Magyarországi Egyetem Geoinformatikai Főiskolai Kar Székesfehérvár. Pirosalma u. 1-3. Tel. 06 22 516 557 Fax 06 22 516 521 Email: [email protected] Honlap: CONTACTS Veronika Weignerová College of Geoinformatics, University of West Hungary Pirosalma u. 1-3. Szekesfehervar HUNGARY Tel. +36 22 516 557 Fax +36 22 516 521 Email: [email protected] Web site:
SZAKMAI ÉLETRAJZ BIOGRAPHICAL NOTES Veronika Weignerová természetföldrajzi
diplomáját a csehországi Plzenben (Nyugat-Bohémiai Egyetem, Földrajzi Tanszék) illetve Prágában (Károly Egyetem,
Természetföldrajzi és Geoökológiai Tanszék) szerezte 2000-ben. Azóta PhD fokozat megszerzésén dolgozik. Fő kutatási területe a városi levegőszennyezés és klíma. 2003-ig a Cseh Tudományos Akadémia Légköri Fizikai Kutatóintézetének Meteorológiai Osztályán dolgozott. 2003 óta a
székesfehérvári Geoinformatikai Főiskolán ESRI ösztöndíjasként tevékenykedik.
Veronika Weignerova is a physical
geographer. She received her BSc in 1997, at Department of Geography, University of West Bohemia in Pilsen and her MSc in 2000, at the Department of Physical Geography and Geoecology, Faculty of Science, Charles University in Prague. Since then she continues in PhD degree. Her research is focused on climate and air pollution in cities. Till 2003 she worked at the Department of Meteorology, the Institute of Atmospheric Physics, under the Academy of Science of the Czech Republic. From 2003 she is ESRI scholar at the College of
