OpenGIS By: Rumana Reaz Arifin Amna Alsarabi

What is Open GIS  Transparent access to mixed geodata and geoprocessing resources in a networked environment.  GIS users can freely exchange data over a range of GIS software systems and networks without having to worry about format conversion or proprietary data types. Source:

Why is Open GIS  The interoperability established by OpenGIS standards enables web users to combine data from many locations by eliminating obstacles created by platform differences. Source:

A sample application A student who is interested in the proximity of new public schools to closed landfills can easily create a map on his browser by connecting to just the data he needs. The student does not know that the data is coming from two different state agencies (TNRCC and TEA), or that the data is kept in two different GIS platform types. With the creation of true OpenGIS interfaces the student can create a map that was never even imagined by the suppliers of the data. Source:

Features of OpenGIS  Makes Geospatial information from different sources  Easy to find and access (regardless to its physical location).  Easy to integrate, even when sources contain dissimilar types of data (raster, vector, coverage, etc.)  Easy to register, superimpose, and render for display.  Incorporate into enterprise information systems.  Additionally, seeks to facilitate the exchange of information among other systems, such as statistical analysis, image processing, document management, or visualization rather than within only GIS.

Open Geospatial Consortium  Creator and manager of an industry wide architecture for interoperable geoprocessing.  In the OGC, more than 330+ commercial, governmental, nonprofit and research organizations worldwide,(like ESRI,Intergraph,Oracle) collaborate in an open consensus process  It was previously known as Open GIS Consortium when it was founded in 1994.

What does OGC do  Much geospatial data is available on the web and in off-line archives, but it is complex heterogeneous, and incompatible.  Common interfaces are the only way to enable combination of data to happen automatically over the Internet.  ……………and OGC brings together the key players and provides a formal structure for achieving consensus on the common interfaces that result in interoperability among diverse geoprocessing systems. source:

OGC Specification  OpenGIS Specifications are technical documents that detail interfaces and are available to everyone at no cost.  Most important OGC specifications are:  OGC Reference Model - a complete set of reference models.  WMS - Web Map Service  WFS - Web Feature Service  WCS - Web Coverage Service  GML - Geography Markup Language  CAT - Web Catalog Service  SFS - Simple Features - SQL  WPS –Web Processing Service (in Testbed)

Web Map Service (WMS)  It provides an mechanism to display CAD and GIS data without costly data conversion.  The WMS utilizes an HTTP request structure that packages a request to one or more servers that understand a WMS request.  The server processes the WMS request and sends back a geo-registered picture to the client in PNG, a GIF, or a JPEG image.

WMS Application-Intergraph’s Support  Intergraph's GeoMedia WebMap running on Windows 2000 and GeoMedia WebMap Publisher uses WMS implementation to deliver data to the MapServer platform.  Therefore, there is no additional configuration required to use the GeoMedia WebMap Publisher created maps; the WMS implementation understands them directly.  Also,the MapServer system then uses that data, to serve maps for users.

 Maps delivered via GeoMedia Web Map and GeoMedia WebMap Publisher WMS Application(contd…) source:  Maps delivered via MapServer.  Here, the building colors are same because, both maps are using the same specification when published and later when read in Mapserver.

Web Feature Service (WFS)  Provides a structure for query and retrieval of geographic features.  It is implemented as messages carried over HTTP request to server.  It uses Geography Markup Language (GML) for transferring features from the server to the client.  The basic Web Feature Service allows querying and retrieval of features.  A transactional Web Feature Service (WFS-T) allows creation, deletion, and updating of features.

Geography Markup Language (GML)  The Geography Markup Language (GML) is the XML grammar, defined by the OGC to express geographical features.  GML serves as a modeling language for geographic systems and open interchange format for geographic transactions on the Internet.

Horton Plaza 41.46, , , , , , , , , , , , , , , , , , ,1646 Gaslamp 44.60, , , , , , , , , , , , , , , , , , , , <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG Stylable//EN" " [ ]> SVG WFS application using GML

Web Coverage Service (WCS)  A WCS provides access to detailed and rich sets of geospatial information.  Operations:  GetCapabilities  DescribeCoverage  GetCoverage  Unlike WMS, which return static maps, WCS provides available data together with their detailed descriptions.  Unlike WFS, which returns discrete geospatial features, the WCS returns representations of space-varying phenomena.

Who will most benefit from Open GIS?  The answer is USERS.  A much larger population of users than currently use GIS and remote sensing software, producers, owners, stewards, and resellers of geodata will be benefited. Because………  The majority of GIS in operation today follow an Homogeneous or Proprietary approach, where the specific GIS applications and capabilities are tightly coupled to their internal data models and structures.  Utilizing an ESRI based software package also requires ESRI proprietary data structure such as ‘Shapefiles’ in order to utilize all analytical aspects of the software.  Within this model, an organization would also typically, adopt an associated vendor file format as an internal standard.

Open GIS provides Distriubuted GIS  The major benefit is the ability to distribute and then combine disparate data to produce new combinatorial datasets, regardless of the original format. Therefore promoting information exchange across organizations.  Users are not restricted to specific vendor systems or formats.  User can access raster and vector data, regardless of its original matter.

Distributed resource integration with OGC service wrappers source:

Is software vendors sacrificing competitive advantage in Open GIS  The answer is No.  Rather they will be benefited because:  The market will be much bigger;  The geoprocessing software integration business will be booming;  Current users will buy the new versions of software that have OpenGIS Conformant interfaces;  There will be new jobs for metadata and data semantics experts, geographers who help build and integrate geographic "content" for web sites etc.  As a whole increasingly the users will be affected.

ESRIs’ support for OGC  ESRI, being the market leader, is a Principal member of Open Geospatial Consortium, Inc. (OGC) and fully encompasses OGC specifications and standards.  ESRI's goal is to support appropriate specifications as they become finalized and to participate in the development of GIS standards via active participation in OGC.  ESRI is able to contribute knowledge in interoperability and ensure the realization of standards compliance in ESRI software products.  ArcGIS is founded upon key interoperability and Web computing concepts and is in use today by tens of thousands of organizations that rely on GIS and IT interoperability  The Shapefile spatial data format is open and published by ESRI.ESRI encourages developers and users to create interchange capabilities to both read and create shapefiles.  ESRI is working with the OGC group to find a simplified GML solution with better performance

ArcWeb Services  ESRI’s ArcWeb Services use the proprietary ArcXML format to serve data.  ArcWeb Services can serve the data as an image service or a feature (vector) service  Provide the same functionality as an OGC WMS or WFS.

OGC Map Service Evalutation  Advantage  As WMS image files are small, a geographic area can be streamed quickly.  WFS allows GIS manipulation of features and filtering due to the fact that it provides more than just an image.  Disadvantage  WMS map is good for viewing but it is only an image, so it cannot be used for analysis like GIS vector data.  WFS performance can be a large problem due to the verbosity of GML documents.

OGC vs. ESRI Map Services  Most map services in operation are serving data in image format, using either ESRI web services with ArcXML or OGC WMS with images and XML metadata  With ESRI software, an ESRI map service can be created and then ‘extend’ it to support OGC standards  ESRI software has better integration with ArcWeb Services than with OGC WMS/WFS  ArcWeb Services have a robust feature set when accessed by ESRI clients, including the ability to sort and query tabular data from the GIS layer that OGC WMS does not have

 Intergraph support OGC WMS.  Microsoft MapPoint Web Service  Customized applications include displaying maps, finding features and geocoded locations, driving directions, proximity searches, thematic data layers. But cannot perform spatial analysis, like geocoding etc.  Google Map  Is a popular way for viewing spatial data, getting directions and finding geocoded address but is not designed to do GIS analysis.  Primarily displays point data – the ability to integrate line and polygon data is not straightforward.  Google Earth  Again, a data display tool, not meant for GIS analysis (yet).  Provides easy access to global remote sensing coverage for context and can display polygons. Other Map Services

In summary…….  Open GIS products is still not market leader but its competing with homogeneous GIS products.  As it provides more flexibility to users by ensuring interoperability, its applications are increasing highly in mainstream GIS.  Some Applications  GeoTools  GRASS  MapSever  OpenEV  OpenMap  Fmaps  MITAB  InovaGIS  OSSIM

Thank You Is Open GIS the Future?