7.4 Data Standards

Before You Start

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Authors

Dr. Manzul Kumar Hazarika and Mr. Chathura Wickramasinghe

Introduction

Geospatial data standards consist of a number of rather independent modules serving data capture, data storage, or data exchange, to mention a few and worldwide standardization of is not simple. The standards would specify an infrastructure and the required services for handling geospatial data, including management, acquisition, processing, analysis, access, presentation, and transfer.

ISO standards for geospatial data have been developed at an abstract level to guarantee long-term stability and such abstract base standards require profiles and implementation specifications in order to be put to use. It has been recognized that the field of geospatial information is so heterogeneous that ISO base standards are not always able to fully meet the requirement for a generic and consistent approach that is expected from an ISO suite of standards. Their implementation produces the necessary feedback to optimize the base standards and the role of Open Geospatial Consortium (OGC) becomes important for issues related to the implementation.

Objectives

The objective of this chapter is to introduce the Open Geospatial Consortium (OGC) standard, which is the most widely used implementation-type standard for geospatial data.

OGC Abstract Standards

OGC is an international industry consortium dedicated to geospatial interoperability by instituting international consensus based standards and OGC standards are most widely used at present worldwide. The OGC could currently be considered the most important consortium in the geographic information community. The vision of the OGC is a world in which everyone benefits from geographic information and services that are made available across any network, application, or platform.

OGC abstract standards provide the conceptual foundation for OGC standards. By basing implementation standards on architecture of abstract standards, which have been harmonized with other standards in the fields of information technology and geospatial data to ensure proper reuse, integration, and harmonization within the OGC implementation standards and those of the other standards bodies. OGC abstract standards are described below.

Topic 1 - Feature Geometry: This abstract standard specifies conceptual schemas for describing the spatial characteristics of geographic features, and a set of spatial operations consistent with these schemas. It defines standard spatial operations for use in access, query, management, processing, and data exchange of geographic information for spatial objects.

Topic 2 - Spatial Referencing by Coordinates: This abstract specification defines the conceptual schema for the description of spatial referencing by coordinates, optionally extended to spatiotemporal referencing. It describes the minimum data required to define one, two, and three dimensional spatial coordinate reference systems with an extension to merged spatiotemporal reference systems.

Topic 3 - Locational Geometry Structures: Locational geometry provides essential and abstract models for technology that is used widely across the GIS landscape. Its first heavy use is in support of simple feature geometry specifications and their spatial reference systems. It provides a discussion of the notion of locational geometry.

Topic 4 - Stored Functions and Interpolation: This topic provides essential and abstract models in support of coverage specifications. Coverages, in general, require two stored functions. The first relates Earth coordinates to the window coordinates in the coverage extent, providing a mapping from the coordinates of a spatial reference system (SRS) to the coverage extent coordinates. The second function assigns values to points in the coverage extent.

Topic 5 - Features: This abstract standard introduces the concept and discusses the essential model for features that have been defined in ISO 19101 and an extensive  primer on the notion of geographic information. It defines the abstract model for feature, feature identifier, identifier scope, identifier change registry, feature repository, and feature collection.

Topic 6 - Schema for Coverage Geometry and Functions: This abstract standard defines a conceptual schema for the spatial characteristics of coverages. Coverages support mapping from a spatial, temporal, or spatiotemporal domain to feature attribute values where feature attribute types are common to all geographic positions within the domain. A coverage domain consists of a collection of direct positions in a coordinate space that may be defined in terms of up to three spatial dimensions as well as a temporal dimension.

Topic 7 - Earth Imagery: This abstract specification defines a reference model for standardization in the field of geographic imagery. This reference model identifies the scope of the standardization activity being undertaken and the context in which it takes place. The scope includes gridded data with an emphasis on imagery.

Topic 8 - Relationships Between Features: Topic 5 of the abstract specification introduces features, an abstraction of the entities in the real world. Entities in the real world do not exist in isolation. Typically, an entity in the real world is related to other real-world entities in a variety of ways. This topic introduces an abstraction for the relationships between entities in the real world.

Topic 10 - Feature Collections: A feature collection is an abstract object consisting of feature instances, their feature schema, and project schema. This document discusses the need (or not) for these concepts, and how feature collections can be used.

Topic 11 - Metadata: This topic refers to ISO 19115 Metadata, which defines a comprehensive metadata schema that is used to fully describe geographic resources. Minimum metadata may be used in resource catalogues and portals for discovery purposes, or comprehensive metadata can be used to support a complete understanding of resources, allowing them to be used properly to their full potential.

Topic 12 - The Open-GIS Service Architecture: This abstract standard identifies and defines architecture patterns for service interfaces used for geographic information and to explain the relationship to the open systems environment model. It presents the geographic services taxonomy and a list of example geographic services placed in the services taxonomy. It also prescribes how to create a platform-neutral service specification, and how to derive platform-specific service specifications that are conformant with this. The standard provides guidelines for the selection and specification of geographic services from both platform-neutral and platform-specific perspectives.

Topic 13 - Catalogue Services: This abstract standard covers geospatial information access services, which include geospatial information retrieval services, geospatial product information services, and geospatial catalogue services. This topic thus covers OGC services for both data discovery and data access. It defines the term "catalogue" to describe the set of service interfaces, which support organization, discovery, and access of geospatial information. Catalogue services help users or application software to find information that exists anywhere in a distributed computing environment.

Topic 14 - Semantics and Information Communities: This abstract specification provides the essential model to permit interoperability across information communities. An information community is a collection of people (a government agency or group of agencies, a profession, a group of researchers in the same discipline, corporate partners cooperating on a project, etc.) who, at least part of the time, share a common digital geographic information language and share common spatial feature definitions.

Topic 15 - Image Exploitation Services: This topic covers the categories and taxonomy of image exploitation services needed to support the use of images and certain related coverage types. Image exploitation services are required to support most aspects of image exploitation, including precision measurement of ground positions and of object dimensions; for example, a variety of services are needed for extracting features from images, or digital elevations from stereoscopic images.

Topic 16 - Image Coordinate Transformation Services:  This topic covers image coordinate conversion services; that is, this part of the abstract specification describes services for transforming image position coordinates to and from ground position coordinates. These services might alternatively be called image geometry model services.

Topic 17 - Location-Based Services: This topic covers location-based/mobile services; that is, this part of the abstract specification describes services that take advantage of mobility and the position or relative position of devices and points, lines, or polygons of service. Important concepts are location, route, and types of service.

Topic 18 - Geospatial Digital Rights Management Reference Model: This abstract standard is a reference model for Digital Rights Management (DRM) functionality for geospatial resources (GeoDRM). As such, it is connected to the general DRM market in that geospatial resources must be treated as nearly as possible like other digital resources, such as music, text, or services.

Topic 20 - Observations and Measurements: This abstract standard defines a conceptual schema for observations, and for features involved in sampling when making observations. It provides models for the exchange of information describing observation acts and their results, both within and between different scientific and technical communities. Observations commonly involve sampling of an ultimate feature of interest. This abstract standard defines a common set of sampling feature types classified primarily by topological dimension, as well as samples for ex situ observations. The schema includes relationships between sampling features.

Keywords

Data Standards, ISO, OGC 

Last update:
15-07-2016

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