Geospatial metadata

Geospatial metadata (also geographic metadata, or simply metadata when used in a geographic context) is a type of metadata that is applicable to objects that have an explicit or implicit geographic extent, i.e. are associated with some position on the surface of the globe. Such objects may be stored in a geographic information system (GIS) or may simply be documents, data-sets, images or other objects, services, or related items that exist in some other native environment but whose features may be appropriate to describe in a (geographic) metadata catalog (may also be known as a data directory or data inventory).

Definition

ISO 19115:2013 "Geographic Information — Metadata"[1] from ISO/TC 211, the industry standard for geospatial metadata, describes its scope as follows:

[This standard] provides information about the identification, the extent, the quality, the spatial and temporal aspects, the content, the spatial reference, the portrayal, distribution, and other properties of digital geographic data and services.[1]

ISO 19115:2013 also provides for non-digital mediums:

Though this part of ISO 19115 is applicable to digital data and services, its principles can be extended to many other types of resources such as maps, charts, and textual documents as well as non-geographic data.[1]

The U.S. Federal Geographic Data Committee (FGDC) describes geospatial metadata as follows:

A metadata record is a file of information, usually presented as an XML document, which captures the basic characteristics of a data or information resource. It represents the who, what, when, where, why and how of the resource. Geospatial metadata commonly document geographic digital data such as Geographic Information System (GIS) files, geospatial databases, and earth imagery but can also be used to document geospatial resources including data catalogs, mapping applications, data models and related websites. Metadata records include core library catalog elements such as Title, Abstract, and Publication Data; geographic elements such as Geographic Extent and Projection Information; and database elements such as Attribute Label Definitions and Attribute Domain Values.[2]

History

The growing appreciation of the value of geospatial metadata through the 1980s and 1990s led to the development of a number of initiatives to collect metadata according to a variety of formats either within agencies, communities of practice, or countries/groups of countries. For example, NASA's "DIF" metadata format was developed during an Earth Science and Applications Data Systems Workshop in 1987,[3] and formally approved for adoption in 1988. Similarly, the U.S. FGDC developed its geospatial metadata standard over the period 1992–1994.[4] The Spatial Information Council of Australia and New Zealand (ANZLIC),[5] a combined body representing spatial data interests in Australia and New Zealand, released version 1 of its "metadata guidelines" in 1996.[6] ISO/TC 211 undertook the task of harmonizing the range of formal and de facto standards over the approximate period 1999–2002, resulting in the release of ISO 19115 "Geographic Information — Metadata" in 2003 and a subsequent revision in 2013. As of 2011 individual countries, communities of practice, agencies, etc. have started re-casting their previously used metadata standards as "profiles" or recommended subsets of ISO 19115, occasionally with the inclusion of additional metadata elements as formal extensions to the ISO standard. The growth in popularity of Internet technologies and data formats, such as Extensible Markup Language (XML) during the 1990s led to the development of mechanisms for exchanging geographic metadata on the web. In 2004, the Open Geospatial Consortium released the current version (3.1) of Geography Markup Language (GML), an XML grammar for expressing geospatial features and corresponding metadata. With the growth of the Semantic Web in the 2000s, the geospatial community has begun to develop ontologies for representing semantic geospatial metadata. Some examples include the Hydrology and Administrative ontologies developed by the Ordnance Survey in the United Kingdom.

ISO 19115: Geographic information — Metadata

ISO 19115 is a standard of the International Organization for Standardization (ISO).[7] The standard is part of the ISO geographic information suite of standards (19100 series). ISO 19115 and its parts define how to describe geographical information and associated services, including contents, spatial-temporal purchases, data quality, access and rights to use.

The objective of this International Standard is to provide a clear procedure for the description of digital geographic data-sets so that users will be able to determine whether the data in a holding will be of use to them and how to access the data. By establishing a common set of metadata terminology, definitions and extension procedures, this standard promotes the proper use and effective retrieval of geographic data.[8]

ISO 19115 was revised in 2013 to accommodate growing use of the internet for metadata management, as well as add many new categories of metadata elements (referred to as codelists) and the ability to limit the extent of metadata use temporally or by user.[9]

ISO 19139 Geographic information Metadata XML schema implementation

ISO 19139:2012 [10] provides the XML implementation schema for ISO 19115 specifying the metadata record format and may be used to describe, validate, and exchange geospatial metadata prepared in XML.[11]

The standard is part of the ISO geographic information suite of standards (19100 series), and provides a spatial metadata XML (spatial metadata eXtensible Mark-up Language (smXML)) encoding, an XML schema implementation derived from ISO 19115, Geographic information — Metadata. The metadata includes information about the identification, constraint, extent, quality, spatial and temporal reference, distribution, lineage, and maintenance of the digital geographic data-set.

Metadata directories

Also known as metadata catalogues or data directories.

(need discussion of, and subsections on GCMD, FGDC metadata gateway, ASDD, European and Canadian initiatives, etc. etc.)

  • GIS Inventory — National GIS Inventory System which is maintained by the US-based National States Geographic Information Council (NSGIC) as a tool for the entire US GIS Community. Its primary purpose is to track data availability and the status of geographic information system (GIS) implementation in state and local governments to aid the planning and building of statewide spatial data infrastructures (SSDI). The Random Access Metadata for Online Nationwide Assessment (RAMONA) database is a critical component of the GIS Inventory. RAMONA moves its FGDC-compliant metadata (CSDGM Standard) for each data layer to a web folder and a Catalog Service for the Web (CSW) that can be harvested by Federal programs and others. This provides far greater opportunities for discovery of user information. The GIS Inventory website was originally created in 2006 by NSGIC under award NA04NOS4730011 from the Coastal Services Center, National Oceanic and Atmospheric Administration, U.S. Department of Commerce. The Department of Homeland Security has been the principal funding source since 2008 and they supported the development of the Version 5 during 2011/2012 under Order Number HSHQDC-11-P-00177. The Federal Emergency Management Agency and National Oceanic and Atmospheric Administration have provided additional resources to maintain and improve the GIS Inventory. Some US Federal programs require submission of CSDGM-Compliant Metadata for data created under grants and contracts that they issue. The GIS Inventory provides a very simple interface to create the required Metadata.
  • GCMD - Global Change Master Directory's goal is to enable users to locate and obtain access to Earth science data sets and services relevant to global change and Earth science research. The GCMD database holds more than 20,000 descriptions of Earth science data sets and services covering all aspects of Earth and environmental sciences.
  • ECHO - The EOS Clearing House (ECHO) is a spatial and temporal metadata registry, service registry, and order broker. It allows users to more efficiently search and access data and services through the Reverb Client or Application Programmer Interfaces (APIs). ECHO stores metadata from a variety of science disciplines and domains, totalling over 3400 Earth science data sets and over 118 million granule records.
  • GoGeo - GoGeo is a service run by EDINA (University of Edinburgh) and is supported by Jisc. GoGeo allows users to conduct geographically targeted searches to discover geospatial datasets. GoGeo searches many data portals from the HE and FE community and beyond. GoGeo also allows users to create standards compliant metadata through its Geodoc metadata editor.

Geospatial metadata tools

There are many proprietary GIS or geospatial products that support metadata viewing and editing on GIS resources. For example, ESRI's ArcGIS Desktop, SOCET GXP, Autodesk's AutoCAD Map 3D 2008, Arcitecta's Mediaflux and Intergraph's GeoMedia support geospatial metadata extensively.

GIS Inventory is a free web-based tool that provides a very simple interface to create geospatial metadata. Participants create a profile and document their data layers through a survey-style interface. The GIS Inventory produces metadata that is compliant with the Federal Content Standard for Digital Geospatial Metadata (CSDGM). The GIS Inventory is also capably of ingesting already completed metadata through document upload and web server connectivity. Through the GIS Inventory web services, metadata are automatically shared with US Federal agencies.

GeoNetwork opensource is a comprehensive Free and Open Source Software solution to manage and publish geospatial metadata and services based on international metadata and catalog standards. The software is part of the Open Source Geospatial Foundation's software stack.

GeoCat Bridge allows users to edit, validate and directly publish metadata from ArcGIS Desktop to GeoNetwork (and generic CSW catalogs) and publishes data as map services on GeoServer. Several metadata profiles are supported.

pycsw is an OGC CSW server implementation written in Python. pycsw fully implements the OpenGIS Catalogue Service Implementation Specification (Catalogue Service for the Web). The project is certified OGC Compliant, and is an OGC Reference Implementation.

CATMDEdit terraCatalog ArcCatalog ArcGIS Server Portal GeoNetwork opensource IME M3CAT MetaD MetaGenie Parcs Canada Metadata Editor Mapit/CADit NOKIS Editor

References

  1. ^ a b c International Organization for Standardization (2014-04-01). "ISO 19115-1:2014(en)". ISO. Retrieved 2016-04-01.
  2. ^ "Geospatial Metadata — Federal Geographic Data Committee". www.fgdc.gov. Retrieved 2016-04-01.
  3. ^ Gene Major and Lola Olsen: "A short history of the DIF". On GCMD website, visited 16 October 2006 Archived 17 October 2006 at the Wayback Machine
  4. ^ MIT Libraries Guide: "Federal Geographic Data Committee (FGDC) Metadata". On MIT Libraries website, visited 16 October 2006 Archived 18 October 2006 at the Wayback Machine
  5. ^ "ANZLIC Metadata Profile Guidelines version 1.2 July 2011" (PDF). ANZLIC. 2011. Retrieved 2011-04-11. ANZLIC[:] The Spatial Information Council of Australia and New Zealand (formerly known as the Australia New Zealand Land Information Council)
  6. ^ ANZLIC Metadata Guidelines: Core metadata elements for geographic data in Australia and New Zealand, Version 2 (February 2001)
  7. ^ ISO 19115 Geographic Information — Metadata. International Organization for Standardization (ISO), Geneva, 2003
  8. ^ "ISO 19115 Metadata Factsheet" (PDF). AG Outreach. Retrieved 2012-11-22.
  9. ^ "NASA Metadata and the New ISO 19115-1 Capabilities - NASA ISO for EOSDIS - Earthdata Wiki". wiki.earthdata.nasa.gov. Retrieved 2016-04-01.
  10. ^ International Organization for Standardization (2012-12-15). "ISO/TS 19139-2:2012(en)". ISO. Retrieved 2016-04-01.
  11. ^ "ISO 19139 Geographic information Metadata XML schema implementation" Archived 9 August 2010 at the Wayback Machine, Marine Metadata Interoperability Project

ANZLIC Metadata Profile Version 1.2 (viewed July 2011)

External links

2d3

2d3 Sensing is an American motion imagery software company based in Irvine, California. It is a wholly owned subsidiary of UK-based OMG plc. Using structure from motion, the company’s suite of products can extract information from images or videos by recreating, manipulating, and enhancing imagery to visualize two-dimensional data into three dimensions. 2d3 follows a COTS business model and conforms to and influences emerging standards such as MISB (Motion Imagery Standards Board) and STANAG.

Bounding volume

In computer graphics and computational geometry, a bounding volume for a set of objects is a closed volume that completely contains the union of the objects in the set. Bounding volumes are used to improve the efficiency of geometrical operations by using simple volumes to contain more complex objects. Normally, simpler volumes have simpler ways to test for overlap.

A bounding volume for a set of objects is also a bounding volume for the single object consisting of their union, and the other way around. Therefore, it is possible to confine the description to the case of a single object, which is assumed to be non-empty and bounded (finite).

C-squares

C-squares (acronym for the concise spatial query and representation system) is a system of geocodes (actually a type of global grid) that provides a basis for simple spatial indexing of geographic features or data. It was devised by Tony Rees of CSIRO Marine and Atmospheric Research (then "CSIRO Marine Research") in 2001-2, and described in the literature in 2003. The notation system of c-squares incorporates a compact encoding of latitude and longitude coordinates into a machine- and human-readable c-squares code, which can then be used either for spatial search or display via a suitable mapping application. The c-squares codes also provide an application- and vendor-independent, interoperable notation system for any gridded data whose units of organization correspond with steps of the c-squares hierarchy (e.g. 5-, 1-, 0.5 degree cells, etc.).

GeoTIFF

GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for the file. The GeoTIFF format is fully compliant with TIFF 6.0, so software incapable of reading and interpreting the specialized metadata will still be able to open a GeoTIFF format file.An alternative to the "inlined" TIFF geospatial metadata is the *.tfw World File sidecar file format which may sit in the same folder as the regular TIFF file to provide a subset of the functionality of the standard GeoTIFF described here.

Geoportal

A geoportal is a type of web portal used to find and access geographic information (geospatial information) and associated geographic services (display, editing, analysis, etc.) via the Internet. Geoportals are important for effective use of geographic information systems (GIS) and a key element of Spatial Data Infrastructure (SDI).

Geographic information providers, including government agencies and commercial sources, use geoportals to publish descriptions (geospatial metadata) of their geographic information. Geographic information consumers, professional or casual, use geoportals to search and access the information they need. Thus geoportals serve an increasingly important role in the sharing of geographic information and can avoid duplicated efforts, inconsistencies, delays, confusion, and wasted resources.

Geotagging

Geotagging or GeoTagging, is the process of adding geographical identification metadata to various media such as a geotagged photograph or video, websites, SMS messages, QR Codes or RSS feeds and is a form of geospatial metadata. This data usually consists of latitude and longitude coordinates, though they can also include altitude, bearing, distance, accuracy data, and place names, and perhaps a time stamp.

Geotagging can help users find a wide variety of location-specific information from a device. For instance, someone can find images taken near a given location by entering latitude and longitude coordinates into a suitable image search engine. Geotagging-enabled information services can also potentially be used to find location-based news, websites, or other resources. Geotagging can tell users the location of the content of a given picture or other media or the point of view, and conversely on some media platforms show media relevant to a given location.

The related term geocoding refers to the process of taking non-coordinate based geographical identifiers, such as a street address, and finding associated geographic coordinates (or vice versa for reverse geocoding). Such techniques can be used together with geotagging to provide alternative search techniques.

Global Change Master Directory

The directory holds more than 28,000 data set descriptions, known as DIFs (Directory Interchange Format). This format is compatible with the Federal Geographic Data Committee's (FGDC) standard and the international ISO 19115 standard. More than 2,500 descriptions of tools and services, known as SERFs (Services Entry Resource Format), are also available to users. The purpose of the directory is to provide users with information on the availability of data and services that will meet their needs, along with efficient access to those data and services. Links are provided, when available, to connect directly to the data or services of interest.

The directory is part of NASA's Earth Observing System Data and Information System (EOSDIS) and also serves as NASA's contribution to the Committee on Earth Observation Satellites (CEOS), through which it is also known as the International Directory Network (IDN). The international participants contribute descriptions of data and services that are held around the world and have provided valuable guidance in the development and direction of the project over the years.

The directory also offers an online metadata authoring tools for those wishing to share knowledge of available data. One of the cornerstones to effective searches within the directory is twelve sets of controlled keywords that assist in normalizing the search. The development of these keywords was initiated over a decade ago. Currently, over 7,000 keywords are controlled, with new sets created for better search refinements, as time permits. The keyword sets are widely used throughout the world and are being translated into many languages. Within the GCMD and the IDN, these controlled keywords can be used in combination with a full-text search engine and also for search refinements.

In addition, virtual subsets of the directory can be created as "portals" for groups wishing to identify their contributions or for those wishing to select a subset for their special interest group. The directory currently receives approximately 8 million hits per month.

Metadata

Metadata is "data [information] that provides information about other data". Many distinct types of metadata exist, among these descriptive metadata, structural metadata, administrative metadata, reference metadata and statistical metadata.

Descriptive metadata describes a resource for purposes such as discovery and identification. It can include elements such as title, abstract, author, and keywords.

Structural metadata is metadata about containers of data and indicates how compound objects are put together, for example, how pages are ordered to form chapters. It describes the types, versions, relationships and other characteristics of digital materials.

Administrative metadata provides information to help manage a resource, such as when and how it was created, file type and other technical information, and who can access it.

Reference metadata describes the contents and quality of statistical data

Statistical metadata may also describe processes that collect, process, or produce statistical data; such metadata are also called process data.

Metadata standard

A metadata standard is a requirement which is intended to establish a common understanding of the meaning or semantics of the data, to ensure correct and proper use and interpretation of the data by its owners and users. To achieve this common understanding, a number of characteristics, or attributes of the data have to be defined, also known as metadata.

Minimum bounding rectangle

The minimum bounding rectangle (MBR), also known as bounding box (BBOX) or envelope, is an expression of the maximum extents of a 2-dimensional object (e.g. point, line, polygon) or set of objects within its (or their) 2-D (x, y) coordinate system, in other words min(x), max(x), min(y), max(y). The MBR is a 2-dimensional case of the minimum bounding box.

MBRs are frequently used as an indication of the general position of a geographic feature or dataset, for either display, first-approximation spatial query, or spatial indexing purposes.

The degree to which an "overlapping rectangles" query based on MBRs will be satisfactory (in other words, produce a low number of "false positive" hits) will depend on the extent to which individual spatial objects occupy (fill) their associated MBR. If the MBR is full or nearly so (for example, a mapsheet aligned with axes of latitude and longitude will normally entirely fill its associated MBR in the same coordinate space), then the "overlapping rectangles" test will be entirely reliable for that and similar spatial objects. On the other hand, if the MBR describes a dataset consisting of a diagonal line, or a small number of disjunct points (patchy data), then most of the MBR will be empty and an "overlapping rectangles" test will produce a high number of false positives. One system that attempts to deal with this problem, particularly for patchy data, is c-squares.

MBRs are also an essential prerequisite for the R-tree method of spatial indexing.

Shapefile

The shapefile format is a popular geospatial vector data format for geographic information system (GIS) software. It is developed and regulated by Esri as a (mostly) open specification for data interoperability among Esri and other GIS software products. The shapefile format can spatially describe vector features: points, lines, and polygons, representing, for example, water wells, rivers, and lakes. Each item usually has attributes that describe it, such as name or temperature.

Standard Interchange Format

Standard Interchange Format, called SIF, is a geospatial data exchange format. A standard or neutral format used to move graphics files between DOD Project 2851 and is currently codified in Content Standard for Digital Geospatial Metadata maintained by the Federal Geographic Data Committee.Unit 69 of the NCGIA Core Corriculum in GIS states that SIF is a "popular data exchange format for many GIS packages" and was "developed to support exchange of data between Intergraph and other systems."Navteq uses Standard Interchange Format (SIF)Another example of data available in SIF format can be found online from the NASA's BOREAS project that also claims that the SIF format is "not well documented."

Additional criticism of SIF, along with recognition of SIF's ubiquity and utility for exchanging data, is acknowledged in the online journal article "Is a Standard Terrain Data Format Necessary?"

Wetlands of the United States

Wetlands of the United States are defined by the United States Army Corps of Engineers and the United States Environmental Protection Agency as "those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetations typically adapted for life in saturated soils. Wetlands generally include swamps, marshes, bogs, and similar areas."

Wetlands can be valued in terms of their contributions to ecological, economic and social systems. Wetlands service these systems through multiple processes including water filtration, water storage and biological productivity. They also contribute the functions of flood control, providing a nutrient sink, groundwater recharge and habitat.The United States is a signatory to the Ramsar Convention, an international treaty for the conservation and sustainable utilization of wetlands. Under the Swampbuster provisions of the Food Securities Act of 1985, farmers who modify existing wetlands may lose their benefits under the USDA farm program. Additionally, every Presidential administration since George H.W. Bush has operated under a "no net loss" of wetlands federal policy goal.

In the United States, some wetlands are regulated by the federal government under the Clean Water Act. Determining the boundary between regulated wetlands and non-regulated lands therefore can be contentious. In reality, there is no natural boundary between the classes that humans define on these gradients (wetland/upland), and this issue is highlighted by the U.S. Fish and Wildlife Service's definition from Classification of Wetlands and Deepwater Habitats of the United States, which defines wetlands as "lands transitional between terrestrial and aquatic systems." Regulations to protect water quality and highway safety require that we create arbitrary boundaries within those gradients, but these boundaries are scientifically definable, and consist of areas where three criterion of the presence of hydric soils, the presence of wetland vegetation, and the presence of appropriate hydrology.

Such regulations must be predictable, reproducible, and enforced otherwise there will be a sacrifice of clean water for development in the case of wetlands regulation (or vice versa), or sacrifice safe travel for quick travel (or vice versa) in the case of speed limits. Determining which wetlands are regulated under section 404 of the Clean Water Act or Section 10 of the Rivers and Harbors Act is termed "jurisdictional determination". Determining the boundary of wetland, whether jurisdictional under sections 404 or 10, or not jurisdictional but still meeting the technical definition of a wetland, that is having the soils, vegetation and hydrology criterion met is called a "wetland delineation", and generally is performed by college graduates with natural science or biology degrees working for engineering firms or environmental consulting firms who are familiar with the 1987 U.S. Army Corps of Engineers Wetland delineation manual.

Defining a boundary depends upon the ground and vegetation characteristics; it is easier to do where the slope of the land is steeper. Deciding if a wetland is a regulated wetland depends on classifying the water in it as "water of the United States" or not. Classifying water as "of the U.S." or "not of the U.S." for purposes of enforcing the Clean Water Act suggests a natural boundary that probably does not exist in nature, and one that was not created regarding air for purposes of enforcing the Clean Air Act.

Indiana Wetlands are the focus of the U.S. National Wetlands Coalition, which in turn has become the focus of some controversy over "false fronts," a form of political camouflage.

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