introduction to geospatial metadata – iso 191** metadata national centers for environmental...

Introduction to Geospatial Metadata – ISO 191** Metadata

National Centers for Environmental Information

(NCEI)

Why ISO Metadata?

Executive Order 12906

• Established the National Spatial Data Infrastructure (NSDI) to support public and private sector applications of geospatial data

• Established an electronic National Geospatial Data Clearinghouse for the NSDI to address data standardization, make geospatial data publicly available, and address redundancy and incompatibility of geospatial information

OMB Circular A-16

• Provides guidance for federal agencies that create, maintain or use spatial data directly or indirectly through the establishment of the National Spatial Data Infrastructure (NSDI) and the Federal Geographic Data Committee (FGDC)

• Establishes guidelines for the management of digital spatial data and the use of those assets. It also appoints the FGDC to the interagency coordinating body for NSDI-related activities

FGDC Endorsed Standards

ISO Geospatial Metadata• ISO – International Organization for Standardization

• Use the 191** series– ISO 19115:2003/Cor 1:2006 Geographic information – – Metadata (!)– ISO 19115-2:2009 Geographic information -- Metadata -- Part 2: Extensions

for imagery and gridded data– ISO/TS 19139:2007 Geographic information -- Metadata -- XML schema

implementation – ISO 19110:2005/Amd 1:2011 Geographic information -- Methodology for

feature cataloguing– ISO 19119:2005/Amd 1:2008 Geographic information -- Services Extensions

of the service metadata model

(!) update now available:ISO 19115-1:2014 Geographic information -- Metadata -- Part 1: Fundamentals

ISO 19115 → Core InformationISO 19115-2 → Extensions for Instrumentation and Gridded Data

ISO 19110 → Entities and AttributesISO 19119 → Services

ISO 19157 → Data Quality

19139XML schema implementation

19115-2 Part 2: gridded data and

imagery

19115Geographic information –

Metadata

19110

MI_

MD_

FC_

19119Services

SV_19157

Understanding ISO Standards

DQ_

19111

ISO Metadata

• Is flexible• Depicts relationships between datasets

and collection level (parent/child relationships)

• Standardizes descriptors through the use of codelists

• Accommodates new technologies (such as documenting services)

• Accommodates International scope• Undergoes revision/review in 5 year cycles

ISO 19115:2003(E)

Whocollected the data?processed the data?wrote the metadata?to contact for questions?to contact to order?owns the data?

Whocollected the data?processed the data?wrote the metadata?to contact for questions?to contact to order?owns the data?

Wherewere the data collected?were the data processed?are the data located?

Wherewere the data collected?were the data processed?are the data located?

Whatare the data about?project were they collected under?are the constraints on their use?is the quality?are appropriate uses?parameters were measured?format are the data in?

Whatare the data about?project were they collected under?are the constraints on their use?is the quality?are appropriate uses?parameters were measured?format are the data in?

Whenwere the data collected?were the data processed?

Whenwere the data collected?were the data processed?

Howwere the data collected?were the data processed?do I access the data?do I order the data?much do the data cost?was the quality assessed?

Howwere the data collected?were the data processed?do I access the data?do I order the data?much do the data cost?was the quality assessed?

Whywere the data collected?

Whywere the data collected?

Metadata written using ISO still answers these important

questions:

Metadata written using ISO still answers these important

questions:

ISO ContentISO Content

Organization and Content of ISO

• organized in “Sections” and “Packages”• Section:

• Groupings of similar information

• Package:• Logical groupings of elements

found in multiple locations within Sections

Main Sections of ISO 19115 and 19115-2 MetadataMetadata Information (MD_Metadata) > (MI_Metadata)

Root element that contains information about the metadata itself. Root contains main sections.

Spatial Representation Information (gmd:spatailRepresentationInfo)

geospatial representation of a resource

Reference System Information (gmd:referenceSystemInfo)

spatial and temporal reference systems used in the resource

Metadata Extension Information (gmd:metadataExtensionInfo)

user specified extensions to the metadata standard used to describe the resource

Identification Information (gmd:identificationInfo)

uniquely identify a resource or resources

Content Information (gmd:contentInfo)

physical parameters and other attributes contained in a resource

Distribution Information (gmd:distributionInfo)

who makes a resource available and how to get it

Data Quality Information (gmd:dataQualityInfo)

quality and lineage (including processing steps and sources) of a resource

Portrayal Catalogue Information (gmd:portrayalCatalogueInfo)

portrayal catalogues used for the resource

Metadata Constraint Information (gmd:metadataConstraints)

constraints on the use of the metadata and the resource it describes

Application Schema Information (gmd:applicationSchemaInfo)

application schema used to build a dataset

Metadata Maintenance Information (gmd:metadataMaintenance)

maintenance of the metadata and the resource it describes

Acquisition Information (gmi:acquisitionInformation)

instruments, platforms, operations and other info of data acquisition (only MI_Metadata)

Package Abbreviations

CI Citation

DQ Data Quality

DS Dataset

EX Extent

FC Feature Catalogue

GM Geometry

LE Lineage Extended (added in ISO 19115-2)

LI Lineage

MD Metadata

MI Metadata for Imagery (added in ISO 19115-2 and replace the root MD)

RS Reference System

QE Data Quality Extended

Unified Modeling Language (UML) Basics

Production Rules of ISO 19115

Unified Modeling Language (UML) is used to represent the relationships among classes

and objects in object oriented programming.

UML Notation

UML - Cardinality

ISO Metadata Implementation 22

Aggregated Class Name

Class Attributes

Attribute Name Cardinality(blank) = required, not repeatable[1..*] = required, repeatable[0..1] = optional, not repeatable[0..*] = optional, repeatable

Attribute TypeCharacter StringCodeset ValueClassDate

Note Field

Example UML

ISO Packages

XML Basics

XML BasicsTag

A markup construct that begins with "<" and ends with ">”. start-tags <section> end-tags </section>

Element A logical component of a document which either begins with a start-tag and ends with a matching end-tag, or consists only of an empty-element tag. Any characters between the start- and end-tags are the element's content, and may contain markup, including other elements, which are called child elements.

<Greeting> Hello, world.</Greeting>Attribute

A markup construct consisting of a name/value pair that exists within a start-tag or empty-element tag. In the example (below) the element step has one attribute, number with a value of “3”:

<step number="3">Connect A to B.</step>

<step number="3">Connect A to B</step><step number="3"/>

Open tag:Close tag:Element name:Attribute:Content:

XML Basics

<gmi:MI_Metadata><gmd:fileIdentifier>

<gco:CharacterString>insert text</gco:CharacterString></gmd:fileIdentifier><gmd:language>

<gco:CharacterString>insert text</gco:CharacterString></gmd:language>

xmlns:gmi=“http://www.isotc211.org/2005/gmi”xmlns:gmd=“http://www.isotc211.org/2005/gmd”xmlns:gco="http://www.isotc211.org/2005/gco"

Namespaces

These codes are called namespaces. The namespace is a container providing context and rules for items. A definition of a term may change, depending on what namespace is applied.

Namespace Abbreviations

gco Geographic Common extensible markup language

gfc Geographic Feature Catalogue extensible markup language

gmd Geographic Metadata extensible markup language

gmx Geographic Metadata XML schema

gss Geographic Spatial Schema extensible markup language

gsr Geographic Spatial Referencing extensible markup language

gts Geographic Temporal Schema extensible markup language

gml Geography Markup Language

xlink XML Linking Language

xs W3C XML base schemas

XML Basics<gmd:dateStamp gco:nilReason=“unknown"/><gmd:metadataStandardName>

<gco:CharacterString> Geographic information - Metadata</gco:CharacterString>

</gmd:metadataStandardName>

Open tag:Close tag:Element name:Attribute:Content:

ISO Attributes• id• idref• idrefs• uuid• uuidref• uom• frame• calendarEraName• indeterminatePosition

• Xlinks• type• href• role• arcrole• title• show• actuate

• nilReason

ISO Attributesid

An identifier for the element that, if specified, must be unique within the XML document. The value of the identifier must always start with a letter, a '_' or a ':'. An XML element can only have one attribute of type ID. The identifiers used in the id attribute are XML Names, which have significant restrictions. They must begin with a letter or an ‘_’ or ‘:’, and, after the first character, be composed only of letters, digits, ., _, and -. This attribute is often mandatory for such items as units and extents.

Ex:

<gml:BaseUnit gml:id="lengthUnitMeters"><gml:identifier codeSpace="meters"/><gml:unitsSystem

xlink:href="http://www.bipm.org/en/si/"/></gml:BaseUnit>

ISO Attributesuuid

The UUIDs are Universally Unique Identifiers, which also have special characteristics. A UUID is assigned to an object when it is created and is stable over the entire lifespan of the objects. A UUID of a deleted object cannot be used again. UUIDs are required for long-term distributed data management and for realizing update mechanisms. These identifiers are also called persistent identifiers. A UUID is a 16-byte number that consists of 32 hexadecimal (0-9 and a-f) values. The values are split into five groups, separated by hyphens in the form 8-4-4-4-12 or 8-4-4-16 for a total of 36 characters (32 values and 4 hyphens).

Ex: uuid=“594D435F-954C-1022-78E7-D62F30CD0592”

ISO Attributes

uuidrefA reference to an XML element in the XML document. The value must correspond to an attribute value of type ID in an existing XML element. The uuidref attribute allows an XML element to refer to another XML element within the same document that has a corresponding id attribute.

ISO AttributesEx:<gmd:contact uuidref="08D95C427FB128479945893256DADE37"/>

References:

<gmd:contact xlink:title="NOAA/OAR/OER - Ocean Exploration and Research"> <gmd:CI_ResponsibleParty uuid="08D95C427FB128479945893256DADE37"> <gmd:organisationName> <gco:CharacterString>NOAA/OAR/OER - Ocean Exploration and

Research</gco:CharacterString> </gmd:organisationName> <gmd:contactInfo xlink:type="simple"> <gmd:CI_Contact> <gmd:phone xlink:type="simple"> <gmd:CI_Telephone> <gmd:voice> <gco:CharacterString>301-713-9444</gco:CharacterString> </gmd:voice>….etc…

ISO Attributes

XLinksThe XML Linking Language (XLink) allows elements to be inserted into XML documents in order to create and describe links between resources, similar to HTML hyperlinks. Linking elements are recognized based on the use of a designated attribute named xml:link and a set of accompanying global attributes. The global attributes are type, href, role, arcrole, title, show, and actuate. If an XLink is used, the following ISO component is not used.

ISO Attributesxlink:href

The value of the href attribute in linking elements contains a locator that identifies a resource, e.g., by a URI-reference or by an XPointer specification.

The xlink href attribute is used to reference a component, and the xlink title attribute is used to apply a human understandable name to the component. Components are snippets of XML describing a specific piece of metadata content, such as information about people, websites, documents, archives, instruments, etc.

XLinks can be used to reference a component from an unresolved metadata record (unresolved meaning that the metadata record contains xlinks).

ISO AttributesUnresolved:<gmd:contact

xlink:href="http://www.ngdc.noaa.gov/docucomp/08D95C427FB128479945893256DADE37" xlink:title="NOAA/OAR/OER - Ocean Exploration and Research"/>

Resolved: <gmd:contact xlink:title="NOAA/OAR/OER - Ocean Exploration and Research"> <gmd:CI_ResponsibleParty uuid="08D95C427FB128479945893256DADE37"> <gmd:organisationName> <gco:CharacterString>NOAA/OAR/OER - Ocean Exploration and

Research</gco:CharacterString> </gmd:organisationName> <gmd:contactInfo xlink:type="simple"> <gmd:CI_Contact> <gmd:phone xlink:type="simple"> <gmd:CI_Telephone> <gmd:voice> <gco:CharacterString>301-713-9444</gco:CharacterString>

etc…

ISO AttributesnilReason

The nilReason attribute is used to explain why an element is not included in the XML. This attribute allows a reason (explaining why the actual value cannot be provided) to exist in place on an actual value. It can have the values “inapplicable”, “missing”, “template”, “unknown”, and “withheld”.

<gmd:date gco:nilReason="unknown"/>

ISO CodeLists

CodeLists are used to refer to a specific codelist value in a register. Codelists contain the attributes “codeList”, “codeListValue”, and “codeSpace”.

• The codeList attribute is mandatory and contains a URL that references a codeList definition within a registry or a codeList catalogue.

• The codeListValue attribute is also mandatory and contains the name of the selected value.

• The codeSpace attribute is optional and refers to the alternative expression of the codeListValue.

ISO CodeLists

<gmd:MD_KeywordTypeCode codeList=“http://www.isotc211.org/2005/resources/Codelist/gmxCodelists.xml#MD_KeywordTypeCode” codeListValue=“theme“ codeSpace="005">theme</gmd:MD_KeywordTypeCode>

ISO 19115 DETAILED VIEW

MD_Metadata

MI_Metadata

Answers questions about instruments or

platforms

spatialRepresentationInfo

Answers questions about how the data

is represented

referenceSystemInfo

Answers questions about projections or datums used

metadataExtensionInfo

identificationInfo

Answers basic questions the data….

contentInfo

Answers more detailed questionsabout the data content

distributionInfo

How do I get the data?

dataQualityInfo

Any data quality reports?

Any processing steps?

portrayalCatalogueInfo

metadataConstraints

Any constraints on the data or the metadata?

applicationSchemaInfo

metadataMaintenance

Any updates to the metadata or the data?

acquisitionInformation

Details on platforms or instruments

Guide to Implementing ISO Metadatahttp://www.ncddc.noaa.gov/

metadata-standards/

• parallels the standard

• provides FAQs

• implementation guide

Workbook of ISO 19115-2

• is a resource for applying the ISO

metadata standard

• provides names and definitions

• describes domain values (valid values that can be assigned to the data element)

• uses a Graphical Representation of the Production Rules

• is a resource for applying the ISO

metadata standard

• provides names and definitions

• describes domain values (valid values that can be assigned to the data element)

• uses a Graphical Representation of the Production Rules

Using the Workbook

Tag: XML tagDefinition: definition of the tagType: type or packageDomain: format of the contentMultiplicity: if something is repeatable and if it is requiredAttributes: XML attributesBest Practices: recommended implementation

Tag: XML tagDefinition: definition of the tagType: type or packageDomain: format of the contentMultiplicity: if something is repeatable and if it is requiredAttributes: XML attributesBest Practices: recommended implementation

fileIdentifier – A unique phrase or string that uniquely identifies the metadata file.

Type: gco:characterStringDomain: free textMultiplicity: optional *this is NAP requirement*Attributes: nilReasonBest Practices: Each metadata record shall have a universal unique identifier (UUID) to distinguish it from others.

Using the Workbook

Using the Graphics

ISO Resources Intro to ISO Training Materials:

http://www.ncddc.noaa.gov/metadata-standards/metadata-training/

NOAA EDM Wiki: https://geo-ide.noaa.gov/wiki/index.php?title=Main _Page

Online ISO Training: ftp://ftp.ncddc.noaa.gov/pub/Metadata/Online_ISO_Training/