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The extraction of topological features from LIDAR DEM data with the application of wireless systems design Antony Winston Roullier-Callaghan, Prof. M. Al-Nuaimi, Dr. D. Kidner
I. Introduction
One effective solution to wireless communications systems design in urban areas is to utilise Digital Elevation Model (DEM) datasets along with Geographical Information Systems (GIS) techniques within radiowave propagation models. The aim of this project is to design and implement a ‘Radio Wave Coverage and Planning System (RAWCAPS) which can predict the signal field strength from a pre-positioned transmitter in a given topographical region. The emphasis of the extracted features is to identify and classify feature outlines such as building footprints and regions of vegetation as these particular features would have the maximum effect on radiowave propagation modelling. II. LIDAR Dataset A certain constraint for the systems being developed is the sole use of LIDAR data as a data source. This is mainly due to the cost effectiveness of LIDAR as opposed to existing topological feature vector data. The LIDAR is used in the form of Digital Elevation Model (DEM) data. The DEMs used in this study where spaced at 1m intervals, with the extent of each site being 500m x 500m. Six sites of the Cardiff UK, LIDAR DEMs were designated for their terrain specific properties. One attribute of the LIDAR DEM, that causes concern is the accuracy of it. As can be seen in Figure 1, ground and roof levels are not separated by thin edges constituting realistic wall widths, thus the need for various processing techniques such as thinning.  Figure 1. LIDAR DEM data
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