Geospatial databases and the evolving role of the surveyor

Oct 2010 | No Comment

The surveyor is being compelled to view survey measurements not in terms of products, but in the broader context of societal applications of the data

Frank Derby, Phd

Associate Professor of Surveying and GIS
Bell Atlantic Center for Technolog
The Pennsylvania State University, USA

With maturation of Geographic Information Systems (GIS) technology, the consumer community as well as decision and policy makers have quickly realized the importance of making sound decisions based on information derived from properly designed geospatial databases. Organizations have created proprietary geospatial databases and governments are rethinking the contents of the National Spatial Data Infrastructure (NSDI). Extensive geographic data acquisition programs including satellite imagery, digital aerial photographs and Light Detection and Ranging (LiDAR) systems at varying ground resolutions, as well as land parcel data are currently in progress around the world. Enabling technologies such as Global Positioning Systems (GPS) and digital image processing software have also facilitated the data processing aspects of these projects. The consuming public has also become more aware of the benefits of geospatial information, and is compelling service providers to provide it. Web-based applications are leading to data accessing and processing techniques such as “mash-ups” and cloud computing services through hosted content and virtual machines which process data from disparate locations.

In the early stages of the data capture and processing stages, the surveyor played a major role in the development of geospatial databases as well as the compilation of graphical data layers. In many of the developed world, a large portion of the traditional surveying aspects of the data capture have been completed. In view of these developments it is now time to look at the role that the land surveyor can play to improve the accuracy and integrity of the geospatial databases and applications, in order to ensure availability of better information to support policy and decision making as well as the needs of the consuming public.

Trends in geospatial data acquisition

Within the last thirty years, GIS technology has evolved from single purpose, project based applications to enterprise systems. Enterprise systems are currently being used by businesses, institutions, industry, local governments and the private sector to provide services to clients, manage resources, and to address multiple issues pertaining to health and human resources, transportation, public safety, utilities and communications, natural resource, defense and intelligence, retail and many more.

To support national development, governments are building national geospatial platforms as the infrastructure that integrates the NSDI to support research, policy matters, socio-economic development, to manage and allocate resources. The NSDI forms the framework that integrates spatial data, computer software, hardware, human resource and technology to meet geospatial data needs of local and municipal governments as well as organizations. In the United States, for example, the NSDI includes, transportation, elevation and bathymetry, hydrography, ortho-imagery, geodetic control, land parcel layers and administrative units. Local and municipal governments are compiling supplementary databases to support land development, taxation and revenue generation purposes, public safety, emergency management and other activities that are relevant to local and municipal governments. Utility companies are also developing databases for oil, gas, electricity, and water lines, together with descriptive data to help them become more efficient and responsive to customer needs. Development of geodatabases has evolved into an industry where commercial entities also produce and market proprietary geospatial databases in addition to providing geospatial applications in the form of services to consumers.

Whereas some of these data capture and compilation activities are conducted by traditional surveying methods, other data acquisition methods which involve extensive aerial photography, LIDAR and satellite imagery are conducted with limited involvement of surveyors. Terrestrial and air-borne GPS technologies have further reduced the need for traditional land surveying services. Mobile mapping technologies which are operated by companies such as Topcon and Trimble have also facilitated the data acquisition process, and further limited the activities of the traditional surveyor, by quickly providing 3-dimnesional georeferenced images of features within the camera range as the vehicle travels around a community. With increasing need for data acquisition, processing, and information dissemination, commercial companies have extended geospatial data acquisition to include marketing of proprietary databases, content hosting, and data analysis. The demand for geodatabases will certainly increase with increased societal needs.


Societal needs for spatially referenced information

Proliferation of geospatial databases is enabling the geospatial industry to change the way decisions are made at the federal, state and local levels. Furthermore, geographic information technology has evolved into a ubiquitous mainstream consumer application. May readers are familiar with the humble beginnings of an application like Mapquest, one of the early geospatial technology applications. The success of this, and other applications, have resulted in other services from Navteq, TeleAtlas, Google, IBM, Microsoft, Apple and many more companies. As a result, consumers can now use applications such as Google Maps, Google Earth, Street View, in-car navigation systems with the ability to navigate to ATMs, specific restaurants, gas stations and be able to direct drivers to navigate detours around traffic congestions and highway constructions sites with ease. Members of the public who are geospatially aware and technology savvy are accessing Web GIS applications to enhance social networking experience through Facebook, Twitter, smart phones, the personal digital assistant (PDA), iPods and iPads. Such demand for geospatially enabled tools and applications have forced equipment manufacturers and service providers to think outside the box. They are responding to consumer requests through hardware improvement, hosted content, virtual machines, mash-ups and cloud computing. All these are possible because of geodatabases, geoprocessing tools and developers’ ability to innovate.

Geodatabases maintained at research institutions, federal and local government repositories, commercial organizations, private a d utility companies, have made it easy for geospatial analysts to access data from a variety of sources for very small fees, if any. This has given geospatial analysts the opportunity to generate information through “mash-ups”, whereby data from disparate repositories are analyzed online to generate information without having the data residing on the host computer. Computer networks consisting of platforms and infrastructure that host geospatial data content, software, processes, vision, and deployment models, all of which are maintained off premises are helping to extend the capabilities of the geospatial technology into cloud computing services. The networks within the cloud allow a user to access the technological capabilities of GIS to be delivered on demand to the end user through the Internet.

Whereas all these applications and innovations are extending the value of information, it is important though, to note that the quality of information depends to a large extent on the quality of the data and the processes through which they have been put in order to derive that information. In this regard, availability is not as important as accuracy, currency, completeness, fitness of use, and resolution. All these qualities of data may have different levels of importance in a particular application. For example, the casual user who wishes to see an aerial view of his neighborhood does not really care if his house is not in the correct geographic location. Many users of location-based applications have, at least on one occasion, been presented with aerial maps with an arrow pointing to the wrong house. Others have been presented with old images in which major constructions or features are missing. However, very few, if any, have been put off by such “simple” mistake in the application. With so many types of spatial data at different scales and accuracies, the need to maintain data quality, integrity and correspondence is presenting new opportunities for surveyors. Indeed, it is extending the services of the surveyor beyond product-oriented services.

The emerging role of the surveyor

Prior to the geospatial technology, the surveyor’s services mostly resulted in products such as topographic, subdivision, and other maps. In recent years, the primary roles of the surveyor within the geospatial technology industry have been to capture and process data for inclusion into the spatial database. There have been few cases where a surveying company has had to develop the geodatabase too. However, today’s geospatial technology places less emphasis on products but rather processes, knowledge infrastructure, capacity building, communication and coordination. The value of the information is based not on the ability to share data or products but the knowledge to assess data quality and to determine their fitness-of use in order to ensure the quality of the information. The surveyor is being compelled to view survey measurements not in terms of products, but in the broader context of societal applications of the data.

With the availability of geospatial data in various formats, from different sources, and having varying lineage, accuracy, currency, and suitability for a defined application, the need to use the right kind of data for the right application is becoming even more important. Granted that metadata standards require that the legend of digital geospatial data which shows the source, original scale, purpose, accuracy, and processes through which the data has been put be provided, it still remains the responsibility of the user to ensure its suitability for a defined application.

Issues with accuracy, resolution, and currency, exist even with aerial photographs, LiDAR, and satellite images too. Although aerial photographs can be processed by simply georeferencing them to known ground coordinates, the quality of the resultant images are different from ortho-rectified images which have been corrected for variation in topography, imperfections in the camera, and aircraft attitude at the instant that each photograph was taken. Although many pieces of spatial data may have associated time stamp, accuracy specifications and other parameters that will assist a knowledgeable person to assess their usefulness, the surveyor’s expertise and training qualifies him in as the best professional to assess the quality and reliability of the ground controls and hence, the accuracy of the processed image.

Furthermore, geospatial technology allows users to perform analysis and investigate phenomena in large geographic regions. The ability to work in large geographic areas implies that it is no longer correct to maintain the flat view of the earth, which used to be the case for small geographic areas. The science of geodesy and map projections which are used to process and present data with respect to the curved earth’s surface is becoming important in geospatial technology applications. The importance of geodesy has now become extremely important not only for those who capture and process spatial data, but to content providers and analysts as well. It is necessary to ensure that a Web-based application service provider has used the correct spatial reference system and that the results have been presented in the correct map projection system also.

Through their training, surveyors are equipped to understand these subject matters and have been able to incorporate them into their products for many years. Geodatabase technology is now requiring surveyors to apply their expert knowledge to assess the quality of the data before they are used in applications. In effect, surveyors are now becoming data analysts and quality control and assurance experts in the world of geospatial technology. This transformation will be facilitated if surveyors would refrain from seeing their services as product-oriented and begin marketing themselves as data analysts as well as quality control and quality assurance specialists to geospatial technology industry.

Adaptation is inevitable. To capitalize on these emerging opportunities, it is necessary that surveying educational institutions adapt by modifying surveying programs and placing more emphasis on data analysis, geodesy, map projections, quality assessment, and geodatabase development and management. The change has already begun. Some surveying institutions are already preparing the new generation of surveyors for these emerging opportunities but the transformation is rather slow.

My Coordinates
His Coordinates
Charles Branch, Subba Rao

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