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It is now widely accepted that GPS meets, under ideal operational conditions, all attributes of a ubiquitous positioning system, i.e. accuracy, reliability and availability. However, its performance quickly deteriorates in certain environments, such as indoors or in urban canyons. In such environments, the demand for location based services (LBS) is growing(More)
Permanent GPS reference station networks are being established worldwide following the establishment of GPS as a primary means for spatial data acquisition. Often these networks are used to augment the regional geodetic framework, such as GPSnet in Victoria, Australia. As a key component of the geodetic infrastructure, high importance is placed upon quality(More)
Recently new location technologies have emerged that can be employed in modern advanced navigation systems. They can be employed to augment common satellite positioning techniques (GNSS) and dead reckoning as they offer different levels of positioning accuracies and performance. An integration of other technologies is especially required in indoor and(More)
The utility and adoption of indoor localization applications have been limited due to the complex nature of the physical environment combined with an increasing requirement for more robust localization performance. Existing solutions to this problem are either too expensive or too dependent on infrastructure such as Wi-Fi access points. To address this(More)
For an increasing number of applications, the performance characteristics of current generation Global Navigation Satellite Systems (GNSS) cannot meet full availability, accuracy, reliability, integrity and vulnerability requirements. It is anticipated however that around 2010 the next generation of GNSS will offer around one hundred satellites for(More)
Spatial Data Infrastructures (SDIs) have been identified as a mechanism through which complete and consistent spatial data sets can be accessed and retrieved. Whilst SDIs have been developing, wireless communication technologies have been undergoing a rapid evolution. The convergence of wireless communications, positioning technology and SDIs are providing(More)
This paper provides a decentralized and coordinate-free algorithm, called DGraF (decentralized gradient field) to identify critical points (peaks, pits, and passes) and the topological structure of the surface network connecting those critical points. Algorithms that can operate in the network without centralized control and without coordinates are(More)