310 likes | 537 Vues
METADATA. “DATA ABOUT DATA” Cody Schank EVSC 468, Spring 2003. Overview. Metadata Basics: Definition, Roles, and Uses FGDC and metadata standards ArcCatalog XML and Stylesheets Editing Metadata in ArcCatalog Importing and Exporting Metadata Creating Metadata.
E N D
METADATA “DATA ABOUT DATA” Cody Schank EVSC 468, Spring 2003
Overview • Metadata Basics: Definition, Roles, and Uses • FGDC and metadata standards • ArcCatalog • XML and Stylesheets • Editing Metadata in ArcCatalog • Importing and Exporting Metadata • Creating Metadata
Formal Definition of Metadata • Metadata provide a description of these data features: • Content • Quality • Condition • Other Characteristics
Four Roles of Metadata • 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 need to acquire an identified set of data • Transfer – data needed to process and use a set of data
Major Uses of Metadata • To maintain an organization’s internal investment in geospatial data • To provide information about an organization’s data holdings to data catalogues, clearinghouses, and brokerages • To provide information need to process and interpret data to be received through a transfer from an external source
Content Standard for Digital Geospatial Metadata • A 90-page document put out by the FGDC in 1998 • Can be accessed at: http://www.fgdc.gov/standards/documents/standards/metadata/v2_0698.pdf
What is the FGDC? • Federal Geographic Data Committee • Established by the Office of Management and Budget (OMB) • Composed of representatives from numerous government departments • FGDC subcommittees establish and implement standards for data content, quality, and transfer; encourage the exchange of info and the transfer of data; and organize the collection of geographic data to reduce duplication
What is the Clearinghouse? • Sponsored by the FGDC • A decentralized system of servers located on the internet which contain field level descriptions of available digital spatial data • The fundamental goal is to provide access to digital spatial data through metadata • Links can be accessed at: http://www.fgdc.gov/clearinghouse/clearinghouse.html
Metadata in ArcCatalog • Properties – i.e. extent of a shapefile's features • Documentation – descriptive information supplied by a person • One of the many purposes of ArcCatalog is to view and create metadata
Default Creation • If an item doesn’t have existing metadata, ArcCatalog will create it by default • Once created, the metadata becomes part of the item itself • It is automatically moved, copied, and deleted along with the item
Automatic Updates • Every time you view metadata, ArcCatalog automatically updates the properties recorded in it with current values. • This ensures that the metadata is kept up to date with changes to the data source
How Metadata is Stored • Metadata created with ArcCatalog is stored as XML • XML = Extensible Markup Language • XML is similar to HTML (Hypertext Markup Language)
XML Lets you define data using tags that add meaning Example: <> 24</price> declares the value “24” to be a price Has become an industry standard for storing data and transferring it across the internet HTML Defines both the data and how it is presented Example: <> 24</B> displays the text “24” in bold font XML vs. HTML
Stylesheets • Stylesheets define how XML data is presented • They are created using XSL • XSL = Extended Stylesheet Language
More on XSL • You can change the metadata’s appearance using different stylesheets • Applies functions and formatting to the data and then specifies how to present the data
Changing the Current Stylesheet • Click the Stylesheet dropdown arrow on the Metadata Toolbar, and click a different stylesheet. • The metadata’s appearance changes according to the rules defined in the new stylesheet
Setting the Default Stylesheet • Click the Tools Menu and Click Options • Click the Metadata Tab • Click the Default stylesheet dropdown arrow and click the stylesheet you want to use • Click OK
Editing Metadata in ArcCatalog • Two different editors: FGDC and ISO Wizard • ISO = International Organization for Standardization • The two editors are different in that they follow two different standards for creating metadata.
Choosing a Metadata Editor • Click the Tools Menu and click options • Click the Metadata tab • Click the Metadata Editor Dropdown arrow and choose either FGDC or ISO • Click OK
Adding Documentation • Click the item whose metadata you want to edit in the Catalog Tree • Click the Metadata Tab • Click the Edit Metadata button on the Metadata toolbar • Document your data using the metadata editor
Importing Metadata • In the Catalog tree, click the item for which you want to import metadata • Click the metadata tab • Click the Import Metadata button on the Metadata toolbar • Click the Format dropdown arrow and click the format of the metadata to be imported • Click the Browse Button • Navigate and click the metadata file whose contents are being imported • If you don’t want ArcCatalog to automatically update the metadata with current properties, uncheck Enable automatic update of metadata • Click OK
Exporting Metadata • In the Catalog tree, click the item for which you want to export metadata • Click the Metadata tab • Click the Export Metadata button on the Metadata toolbar • Click the Browse button • Navigate to the folder in which the exported metadata is to be stored, type a name for the file, then click save • Click the format dropdown arrow, and click the format in which you want to export the data • Click OK
Creating Metadata • If you choose not to have ArcCatalog update metadata automatically… • You can manually update an item’s metadata by clicking the Create/ Update button on the Metadata toolbar
Choosing How metadata is created and updated • Click the Tools menu and click Options • Click the metadata tab • Check the appropriate boxes to have the Catalog automatically create or update metadata • Uncheck the appropriate boxes if you prefer to manually create or update metadata • Click OK
Creating and Updating metadata manually • In the Catalog tree, click the item whose metadata you want to create or update • Click the Metadata tab • Click the Create/ Update Metadata button on the Metadata toolbar
Manual More accurate and detailed metadata Automatic Helps reduce maintenance costs Manual vs. Automatic Update
Demonstrations • Demonstrations in ArcCatalog
The End • Any Questions?