In this new world, geospatial service interface and encoding standards provide the foundation both for convergence and for communication between applications and the cloud
Cartographic information products are increasingly delivered by means of web services. Requests for a specific cartographic service and the returned responses can be conveyed using networks, platforms and applications other than the Internet and the Web. However, service-oriented cartography usually refers to Web-based mapping applications that utilise remote Web servers to deliver maps to users.
Today, “apps” running on software in the “cloud” play a central role in providing collections of visual symbols we call “maps”. Computer-spoken navigation instructions can also be considered as service-oriented cartography. The ubiquity of mobile devices requires an extended cartographic presentation that merges indoor/outdoor navigation and visualisation. In this new world, geospatial service interface and encoding standards enable services from different providers to be used together.
OGC standards are freely available technical specifications that detail geospatial interfaces or encodings. Software developers use these specifications to build open interfaces and encodings into their products and services.
Some OGC standards are extensions of other standards organisations’ standards. The OGC Geospatial eXtensible Access Control Markup Language, for example, built on the OASIS eXtensible Access Control Markup Language (XACML) standard, supports the declaration and enforcement of geospatial data access rights across jurisdictions. The OGC KML Standard is an XML language focused on geographic visualisation, including annotation of maps and images. KML was brought into the OGC by Google to be made an open international standard. Some of the other OGC standards are described below:
- The OGC Web Map Service (WMS) Interface Standard provides a simple HTTP interface for requesting geo-registered map images from one or more distributed geospatial databases.
- The OGC Web Map Tile Service (WMTS) Interface Standard enables better server performance in applications that involve many simultaneous requests. It returns small pre-generated images or reuses identical previous requests that follow a discrete set of tile matrices.
- The OGC Symbology Encoding Standard (SE) defines an XML language for styling information that can be applied to digital geographic feature and coverage data. SES is independent of any OGC Web Services descriptions and can therefore be used to describe styling information in non-networked systems such as desktop GIS.
- The OGC Styled Layer Descriptor (SLD) Profile of the WMS standard Courtesy: Thomas Kolbe , Berlin TU defines an encoding that extends the WMS standard to allow user-defined symbolisation and colouring of geographic feature and coverage data.
- The OGC City Geography Markup Language (CityGML) Encoding Standard is an open data model and XML-based format for the storage and exchange of virtual 3D city models. It allows the reuse of the same data in different application fields.
- Candidate OGC standards for 3D portrayal include the OGC Web 3D Service (W3DS) and Web View Service (WVS) Interface standards.
- The OGC Web Processing Service (WPS) Interface Standard provides rules for standardising inputs and outputs (requests and responses) for geospatial processing services. The standard also defines how a client can request the execution of a process, and how the output from the process is handled. This can be of interest in service-oriented cartography.
Many specifications are in the process of being advanced toward adoption by the OGC membership as official OGC standards. Some of them are listed below.
Augmented Reality Markup Language (ARML) – The candidate OGC ARML (Augmented Reality Markup Language) Encoding Standard 1.0 is a descriptive, XML based data format, specifically targeted for mobile Augmented Reality (AR) applications. ARML focuses on mapping georeferenced Points of Interest (POIs) and their metadata, as well as mapping data for the POI content providers publishing the POIs to the AR application.
GeoPackage – The candidate OGC GeoPackage Encoding Standard provides an open, non-proprietary, platform-independent SQLite container for distribution and direct use of all kinds of geospatial data, including vector features and tile matrix sets. GeoPackage supports delivery of geospatial application services and associated data in disconnected or limited network connectivity environments where open, sharable geospatial data to support their applications is frequently unavailable.
InDoorGML 1.0 – It aims to provide a common schema framework for interoperability between indoor navigation applications, which cover a wide spectrum of application areas such as indoor LBS, indoor web map services, indoor emergency control, guiding services for visually handicapped persons in indoor space, and indoor robotics.
Moving Object Snapshot – This candidate standard provides a way of describing in simple terms the motion of an object, such as a car driving through city streets or a person walking in a park.
OGC Web Services Context – The candidate OGC Web Services (OWS) Context standard encodes the key elements of a common operating picture: the geographic area, an optional time range, and an ordered series of layers from different services or inline content. This allows a situational awareness view of one user to be passed to other users so that the same picture can be reconstructed.
Rapid technological advances will definitely have implications for cartography. Therefore, cartographic community should participate in the OGC’s consensus process and introduce requirements that will shape future international standards.