The scope of ISO 19109 is defined as "... the rules for defining an application schema, including the principles for classification of geographic objects and their relationships to an application schema." Using the Unified Modeling Language, software applications that provide access to geospatial data, such as framework, would be defined in a consistent way so as to improve sharing of data between applications and even allow for real-time interaction between applications.
Before one can allow software to reliably access mapped features stored in remote data systems, there must first be a common understanding about the nature and composition of the objects being managed. ISO 19109 includes guidance principles for classifying geographic objects. The usefulness of any information is reduced when the meaning is unclear, especially and commonly across different application domains. If different classifications are defined using a consistent set of rules, that ability to map one classification to another and retain the meaning will be greatly increased. This is also known as the semantic translation of one representation of an object in one system, for example a road or river segment, to that in another.
These rules will be used by geographic information users when classifying geographic objects within their applications and when interpreting geographic data from other applications. The rules and principles could also be used by geographic information system and software developers to design tools for the creation and maintenance of classification schemes.
Very closely related to the schema definition of ISO 19109 is the standard proposing a feature cataloguing methodology, ISO 19110. It is intended to define the approach and structures used for an information provider to store the identity, meaning, representation, and relationships of concepts or things in the real world as they are managed in online systems. A feature catalog, then, acts as a dictionary for feature types or classes that can be used in software. The definition of a single international, multilingual catalog would have tremendous value. Whether this catalog was used in all applications or only used as a neutral form when moving data from one application to another, it could simplify the problem of mapping the catalog of one application to the catalog of another. However, the feasibility of such a task is in question and will be investigated as a part of this work item in the TC 211 work group. The cataloging task will use the input from the Rules for Application Schema work item and cannot be completed before that item is completed.
Publishing an application schema with a feature catalog for a given data set of common interest can provide the basis for framework data definitions of use to global, regional, national, and local data. Done carefully, schemas and feature catalogues could be similarly constructed for existing framework-like data in order to enable discussion among participants, and transformation of content into conforming framework data sets.
A project to develop framework specifications in Switzerland, known as InterLIS, has had marked success with this approach. Common definitions of data layers exist as target specifications that are matched to various degrees by participant organisations. As a result, software that is designed to interact with the InterLIS application model will work against data sets from different sources and organisations. The application framework is designed to be a scalable one to allow the participation of minimal data sets with lesser application functionality and more complex data sets with maximal application functionality.
Common Identities of Real World Objects
In many framework implementations, there will not be necessarily one authoritative geometric representation of a feature in the real world. Several national systems have proposed the use of a common or permanent feature identifier to be associated with the object in the real world so that different representations and attributes of that object on maps can be cross-referenced. Having well-known identities of features established with a coding system within a community greatly assists in the association of attribute information to real-world objects where such attributes may not reside in a GIS or spatially-enabled data base. Also, multiple representations of real world objects may be linked to the identity code, to provide views of an object that is changed over time or that has different degrees of spatial resolution at different scales of data collection or representation. This becomes a logical model for organizing related geospatial information.
The management of a common or "permanent" feature identity needs to be undertaken within the community with permission granted to certain participant organisations to create or adjudicate these identities. In Canada, there is an effort to create a data alignment layer of well-known features or intersections of features to help vertically integrate spatial data from different sources. These features and intersections will have published identifiers, some sense of positional accuracy, and source information. In the United States, the National Hydrography Data set includes a permanent feature identifier for segments of river and water bodies between points of confluence. In other national, regional, and global settings, agreement on management and assignment of feature identifiers -- building upon a sound feature cataloguing approach -- will be essential in building up compatible framework data across political boundaries.
Candidate National Framework Categories
A variable number of data layers may be considered to be common-use and of national or trans-national importance as "framework" data. Framework layers commonly nominated in national context include:
Candidate Global Data Categories
The Global Mapping concept was articulated by the Ministry of Construction of Japan as a response to the United Nations Conference on Environment and Development held in Brazil in 1992. Agenda 21 is an action program drawn up by the conference, and it clearly makes the case that global baseline spatial data is important to society's interaction with the environment. The Global Mapping Project, also known as Global Map, is addressing the compilation of suitable spatial data products from existing international and national sources. This provide a public set of reference data at trans-national to global scales to assist decision-makers and society in depicting global environmental concerns.
Progress is being made in selecting and enhancing these general purpose spatial data layers originally based on VMAP Level 0 (also known as Digital Chart of the World) for vector themes, Global Land Cover Characteristics Database from the U.S. Geological Survey (USGS) for land cover, land use and vegetation, and the 30-second GTOPO30 product also hosted by the USGS. Global Map Version 1.0 specifications for data organisation were adopted at the International Steering Committee for Global Mapping (ISCGM) meeting held in conjunction with the Third GSDI Conference in Canberra, Australia in November 1998. As of February 2000, 74 countries are participating in the collection or aggregation of large-scale map products to update and package the above data sources.
Recommendations
The development of common data specifications is an arduous task to undertake by oneself or by a single organisation. For the development of the GSDI the following recommendations are made:
The Cookbook authors recommend that Global Map specification be adopted for trans-national applications requiring land cover/use, vegetation, transportation, hydrography, administrative boundaries, populated places, and elevation data.
The global map content specification defines a simple content model with a small number of feature types and attributes suitable for the construction of base cartography at regional scales. Evaluate the level of detail with respect to a given GIS or mapping application. It may require extension to suit your base requirements.
The Cookbook authors suggest prototyping and review of pending ISO 19109 and 19110 standards on application schema and feature catalogues for use in GIS applications.
The ISO work in progress formalises the description of features and feature collections for individual applications that can facilitate the proper access and transformation of geospatial data held in online systems in near real time. This extends the capabilities of the individual in working with dynamic information held in distributed locations, as will be discussed in Chapter 6 in greater detail. National and global framework data, as well as non-framework data will be made more accessible and semantically correct through such technologies.
References and Linkages
Australian Spatial Data Infrastructure Fundamental Data
Framework Home Page, U.S. Federal Geographic Data Committee
Global Mapping Specifications - Version 1.0, 20 November 1998
Interlis Project Home Page, Switzerland
It is likely for this list to grow as custodians of data identify and promote their data as necessary to increasingly advanced applications and user environments.
Data appropriate to a given type of geospatial analysis will require information at a range of resolutions and degrees of detail.
http://www.auslig.gov.au/asdi/ffdata.htm
http://www.fgdc.gov/framework/framework.html
http://www.auslig.gov.au/mapping/global_m/specv1_0.htm
Chapter Two | Context and Rationale | Organisational Approach | Implementation Approach