The development of a Global Spatial Data Infrastructure requires the integration of spatial information from a wide number of actors using different technologies through space and time. This fusion of geoinformation poses unique representation challenges because the requirements for 3-D representation are different than traditional 2-D representation. Earl F. Burkholder is the author of The 3-D Global Spatial Data Model: Foundation of the Spatial Data Infrastructure. The book explains why a new Global Spatial Data Model (GSDM) which links both functional and stochastic models together can provide a single horizontal and vertical data model for global use.
THE 3-D GLOBAL SPATIAL DATA MODEL
Foundation of the Spatial Data Infrastructure
Earl F. Burkholder
392 pages; 2008 – ISBN-10: 1420063014
Review by Jeff Thurston
Many people create and use spatial daily around the world. Their needs and goals vary from place to place and the technologies they use are also different. A surveyor will use a higher precision instrument than a forest inventory specialist with a GPS. A transportation professional may be satisfied with accuracy approaching one meter, whereas an architect is more than likely interested in higher precision when it comes to measurement. Meanwhile, the mining industry seeks to locate resources in 3-D space as do oceanography scientists beneath the world’s oceans.
Each of the pieces of geoinformation require a suitable method for not only representing where they occur, but also one that considers the unique characteristics of their physical location relationships and functional behaviour. In addition, most measurements and geographic related phenomenon have been represented in 2-D necessitating the development of projections (referred to as pseudo-3D herein) and coordinate systems for representation of 3-D features and events.
What-if there was one spatial data model that could handle all types of geoinformation?
Earl F. Burkholder says, “the GSDM is a collection of mathematical concepts and procedures that can be used to manage spatial data both locally and globally.” It is based on the geometric aspects that enable a Global Spatial Data Infrastructure. The GSDM finds its origin at the earth’s enter of mass where a right-handed, Cartesian coordinate system begins. It is an Earth-centred Earth-fixed coordinate (ECEF) coordinate system.
Burkholder explains the development of the GSDM and outlines how it applies and can be linked to engineering, mapping, computer graphics, transportation, geography and surveying among many other disciplines. Considerable explanation is provided with respect to mathematical calculations and stochastic model components – “accuracy with respect to what?” as the author indicates.
The mathematical models for this work are publicly available, although the software package that performs the geometric calculations, called “BURKORD” is trademarked and is licensed for a fee if products or services based on its use are developed and sold.
The book explains in detail what spatial measurements are and how they relate to spatial data purposes. In this sense readers will find this book unique because it not only includes surveying measurement concepts, but how they integrate into wider spatial data infrastructures. Geodesy from a global – and local standpoint is included.
I found this book interesting because of the breadth of measurement techniques covered and Burkholder discusses not only spatial data accuracy, but also spatial data quality, a necessary consideration when speaking about fused geoinformation systems.
“But regardless of the technology used to measure fundamental physical quantities, the GSDM provides a common universal foundation for expressing fundamental spatial relationships.” This fact leads to the author’s observation that the GSDM enables viewing and consideration of conflicting spatial data sets – a key component of SDI – although we sometimes simply call them ‘disparate’ sources of information.
Burkholder speaks about “derived spatial data as being computed from primary spatial data” such as that from geodetic coordinates, UTM coordinates, state plane coordinates, projections datum coordinates and other mathematically defined systems. The costs of primary spatial data are still high, which probably explains why so many people attempt to compute geoinformation without collecting raw, high quality data. On the topic of derived data, the author says, “derived data can be computed, used, and discarded without detrimental economic consequences.” He also ponders the question “what makes spatial data lose their value?” Answer: the cost of replacement.
The book explores coordinate systems closely and logic, arithmetic and algebra are discussed. An overview of geometry is also included and many descriptions for well-known terms are presented. Bearings and azimuths are explained and the operating principles of calculators and their operation is outlined (for those interested in decimal degree to trigonometry measurement calculation).
The GSDM has no need for geoid calculation since it is directly calculated from the earth’s centred origin. In fact, the earth’s curvature is not determined at all because it is handled implicitly. Readers will find an informative discussion about datums and projections and their history and a chapter on Global Navigation Satellite Systems (GNSS) is also present, together with techniques for position calculation. A chapter on spatial data use is included as is a chapter on the use of GSDM itself.
The 3-D Global Spatial Data Model: Foundation of the Spatial Data Infrastructure is a unique book. It includes all of the concepts many 1st and 2nd year university and college students need to know such as definitions for measurement, datums, projections and basic survey calculations. The connection from surveying to spatial data is seldom made in most texts and that is where this book shines. It not only discusses measurement in terms of spatial data, but seeks to orient the reader toward the issues relating to integrating that data with others locally and globally. Whether one is a surveyor, GIS professional or CAD design specialist performing engineering, this book will be useful due to the explanations relating to spatial integration surrounding measurement.
I rate this book highly and would suggest that it could become a primary text for those courses and individuals embarking upon a spatial information career path. Beyond that, it is required reading for those interested in spatial data infrastructures (SDI).
Jeff Thurston is Co-founder Vector1 Media and editor, Europe, Middle East, Africa and Russia for V1 Magazine.