In an urban environment, the occlusion of satellite broadcasts varies across space and thus, preplanning for collection of GPS points requires consideration of these obstructions. This paper presents a GIS embedded model (ArcGIS and ArcObjects) for predicting GPS error via modeling PDOP in an urban environment. The "skyview" model predicted PDOP for spatial locations as a function of the percen...

The recent availability of detailed geographic data permits terrain applications to process large areas at high resolution. However the required massive data processing presents significant challenges, demanding algorithms optimized for both data movement and computation. One such application is viewshed computation, that is, to determine all the points visible from a given point p. In this pap...

The calculation of viewsheds is a routine operation in GIS and is used in a wide range of applications. Many of these involve the siting of features, such as radio masts, which are part of a network and yet the selection of sites is normally done separately for each feature. The selection of a series of locations which collectively maximise the visual coverage of an area is a combinatorial prob...

This study evaluated the positioning accuracy of moving forest harvesters using global navigation satellite system (GNSS) signals under a canopy, and developed approaches for forecasting mature spruce canopy cover. Real-time kinematic with Trimble R12 receiver on top harvester achieved high accuracy, 86% observations meeting maximum precision 8 mm. However, presence cover hampered GNSS’s perfor...

Quantifying the spatial extent, location and habitat associations of invasive tree species is critical to predict their future spread prioritise areas for management. Species–environment relationship analyses are useful tools understanding predicting potential geographical distribution these species; however, such require rigorous extensive data about presence and, crucially, area surveyed. Her...

Public Closed Circuit TeleVision (CCTV) initiatives have been utilized as methods of monitoring public space for over two decades. Evaluations of these efforts to reduce crime have been mixed. Furthermore, there has been a paucity of rigorous evaluations of cameras located in the USA. In this analysis, crime in the viewshed of publicly funded CCTV cameras in Philadelphia, PA, is examined using ...