Εvaluation of Reliability of Hellenic Positioning System (HEPOS) in Forest and Forest Area
Chrysanthi Argiropoulou¹, Kosmas Aristotelis Doucas^2
1Chrysanthi Argiropoulou, PhD Candidate, Department of  Forest Service of Serres, Greece, Forestry and Natural Environment, Laboratory of Mechanical Science and Topography, Aristotle University, Thessaloniki Greece.
²Prof. Kosmas Aristotelis Doucas, Department of Forestry and Natural Environment, Laboratory of Mechanical Science and Topography, Aristotle University, Thessaloniki Greece.
Manuscript received on 9 May 2015 | Revised Manuscript received on 25 May 2015 | Manuscript Published on 30 May 2015 | PP: 63-68 | Volume-4 Issue-12, May 2015 | Retrieval Number: L20690541215/15©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Abstract: Permanent reference station networks have been already established all over the world and used with success in geodetic and surveying applications for high accuracy positioning. Following the example of this development, the Hellenic Positioning System (HEPOS) was created in Greece. The system constitutes the first Greek Network of Permanent GPS Reference Stations. The aim of the paper is to evaluate the reliability of the system in forest and forest lands. So an implementation of the system HEPOS and three RTK techniques of it – Single-Base, technique with Virtual Reference Stations (VRS-RTK) and Network DGPS –took place in five different forest environments: a) in an axis of forest road, b) under the canopy of high forest of broadleaf oak (Quercus frainetto), c) in forest grassland, d) in an urban type environment (buildings in forest environment) and e) a trigonometric point. The measurements were carried out in the University forest of Taxiarhi-Vrastanon Halkidikis. The results shows that the Single Base technique provides more precise results than the VRS technique, while the latter proved more effective than the Network DGPS technique under the canopy of high forest of broadleaf oak (Quercus frainetto) and in an urban type environment (buildings in forest environment). A variation in relation to the above conclusion is observed in measurements on the axis of the forest road, in the forestal grassland and on the trigonometric point, where the Single Base and VRS techniques appear to be equal and in any case superior to the technical Network DGPS technique. As for the measurement environments, the best results of positional accuracy were presented in order of priority, on the trigonometric point, in the forestal grassland, in the urban type environment (buildings in forest environment), in the axis of forestal road and finally under the canopy of high forest of broadleaf oak (Quercus frainetto). In the DGPS technique the line was different with the best results appear in the forestal grassland, then in the trigonometric point, in urban type environment (buildings in forest environment), in the axis of forestal road and finally under the canopy of high forest of broadleaf oak (Quercus frainetto).
Keywords: Permanent Reference Station, VRS, MAC, Single Base, Network DGPS, RTK, Accuracy.
Scope of the Article: Forest Genomics and Informatics