It is common for people travelling for recreational purposes to want routes that present remarkable view, continuity in their viewshed with scenes that are unusual or rare for their everyday routine. Geographical Information System (GIS) routines today, embody the ability to calculate the viewshed and to combine visibility basic analysis with digital elevation data within their spatial database. In this paper, with the use of GIS applications and tools regarding elevation data management, we attempt to define parameters that will help us to position locations and routes which are suitable in terms of their viewshed range, and, further on, to present this information on a map. We then proceed to a case study at Attica Prefecture in Greece, where we examine cases of point and area locations as well as routes as it concerns their visibility.
digital elevation model, extended visibility, GIS, line of sight, viewshed
 Fisher, P.F., Reconsideration of the viewshed function in terrain modelling. Geographical Systems, 3, pp. 33–58, 1996.
 Fisher, P.F., An exploration of probable viewsheds in landscape planning. Environment and Planning B: Planning and Design, 22, pp. 527–546, 1995.
 Travis, M.R., Elsner, G.H., Iverson, W.D., Johnson, C.G., VIEWIT: computation of seen areas, slope and aspect for land-use planning. General technical report PSW – 11/1975 (#Excerpt), Pacifi c Southwest Forest and Range Experiment Station, USDA, Forest Service, USA, 1975.
 Lee, J., Digital analysis of viewshed inclusion and topographic features on digital elevation models. Photogrammetric Engineering & Remote Sensing, 60(4), pp. 451–456, 1994.
 De Floriani, L. & Magillo, P., Computing visibility maps on a digital terrain model. Proceedings of European Conference, COSIT ’93, Spatial Information Theory – A Theoretical Basis for GIS, eds. A. Frank & I. Campari, Italy, September 1993, pp. 248–269, 1993.
 Magillo, P., De Floriani, L. & Bruzzone, E., Updating visibility information on multiresolution terrain models. Proceedings of European Conference, COSIT ‘93, Spatial Information Theory – A Theoretical Basis for GIS, eds A. Frank & I. Campari, Italy, September 1993, pp. 279–296, 1993.
 Caldwell, D.R., Mineter, M.J., Dowers, S. & Gittings, B.M., Analysis and visualization of visibility surfaces. Proceedings of the 7th International Conference on GeoComputation, UK, 8–10 September 2003.
 Fowler, T., Pocemich, M., Braid, J., Holmes, A. & Bateman, R., Quality assessment of the national ceiling and visibility analysis product. Joint Session 1. Calibration and Verifi cation of Probabilistic Forecast Products (Joint between 12th Conference on Aviation Range, Aerospace Meteorology and the 18th Conference on Probability and Statistics), 1 February 2006.
 O’ Sallivan, D. & Turner, A., Visibility graphs and landscape visibility analysis. International Journal of Geographical Information Science, 15(3), pp. 221–237, 2001.
 Tsouchlaraki, A. & Achilleos, G., Managing visual impacts through a GIS: visibility analysis for the design of a sanitary landfi ll site. Second International Conference on Waste Management and the Environment ‘WASTE MANAGEMENT 2004’, Wessex Institute of Technology (England), Rodos, Greece, 29 September–1 October 2004.
 Ying, S., Li, L., Mei, Y. & Peng, X., Incremental terrain visibility analysis. Proceedings of SPIE – Geoinformatics 2006: Geospatial Information Science, October 2006.
 Sparkes, A. & Kidner, D., A GIS for the environmental impact assessment of wind farms, http://gis2.esri.com/library/userconf/europroc96/PAPERS/PN26/PN26F.HTM, accessed 17 July 2007, 1996.
 Rios-Urban, M. & Chasan, R., Uses of viewshed analysis models in planning and neighborhood preservation, http://gis2.esri.com/library/userconf/proc05/papers/pap2090.pdf, accessed 17 July 2007, 2005.
 Skov-Petersen, H. & Snizek, B., To see or not to see: assessment of probabilistic visibility. 10th AGILE International Conference on Geographic Information Science 2007, Aalborg University, Denmark, 2007.
 Athanson, M., Modelling bullet trajectories on historic battlefi elds using exterior ballistics and target-oriented visibility. Proceedings of the Conference: Computer Applications and Quantitative Methods in Archaeology, CAA2006, Fargo, USA, 18–23 April 2006.
 Albanese, J., Spatial and temporal analysis of bluestone quarries in New York State. Proceedings of the Northeastern Section – 40th Annual Meeting, 14–16 March, 2005.
 Franklin, Wm.R. & Ray, C.K., Higher isn’t necessarily better: visibility algorithms and experiments. Advances in GIS Research: Sixth International Symposium on Spatial Data Handling, eds T.C. Waugh & R.G. Healey, Taylor & Francis: Edinburgh, pp. 751–770, 1994.
 Kim, Y.H., Rana, S. & Wise, S., Exploring multiple viewshed analysis using terrain features and optimisation techniques, http://eprints.ucl.ac.uk/archive/00000191/01/kim.pdf, accessed 17 July 2007.
 Jiang, B., A structural perspective on visibility patterns with a topographic surface. International Journal: Transactions in GIS, 9(4), pp. 475–488, 2005.
 Jude, S.R., Jones, A.P., Watkinson, A.R., Brown, I. & Gill, J.A., The development of a visualization methodology for integrated coastal management. Coastal Management, 35, pp. 525–544, 2007.
 Coll, N., Fort, M., Madern, N. & Sellares, J.A., Multi-visibility maps of triangulated terrains. International Journal of Geographical Information Science, 21(10), pp. 1115–1134, 2007.
 Achilleos, G. & Tsouchlaraki, A., Visibility and viewshed algorithms in an information system for environmental management. Proceedings of the Conference: Management Information Systems 2004, Malaga, Spain, 2004.
 Achilleos, G., Considering elevation uncertainty for managing probable disasters. The 1st International Symposium on Geo-information for Disaster Management, Delft University of Technology, ISPRS, EuroSDR, AGILE, GIN, UN, Delft, the Netherlands, 21–23 March 2005.
 Kim, J.J., High target visibility analysis, ASPRS/ACSM, Annual Convention & Exposition Technical Papers, Nevada, 25–28 April 1994, pp. 301–306, 1994.
 Felleman, P.J., Landscape visibility. Foundations for Visual Projects Analysis, John Willey & Sons: NY, 1986.
 USDA Forest Service, The Visual Management System, Government Printing Offi ce, Ag. Handbook 462, Washington, 1973.
 Tsouchlaraki, A., Assessment Methodology for Physical Relief Optical Value, PhD dissertation, Dept. of Rural & Surv. Eng., NTUA, Athens, 1997 (in Greek).
 Tsouchlaraki, A., A quantitative model for evaluating landforms visual value. International Journal of Environmental Studies, Routledge – Taylor & Francis Group, 62(3), June 2005, pp. 341–351.
 Mougiakakou, S.G., Tsouchlaraki, A., Cassios, C., Matsopoulos, G., Nikita, K.S. & Uzunoglou, N., SCAPEVIEWER: preliminary results of a landscape classifi cation system based on neural network technology. Ecological Engineering: The Journal of Ecotechnology, Elsevier Science Publishers BV, 24(1–2), pp. 5–15, 2005.
 Lynch, K., The Image of the City, MIT Press: Cambridge, 1985.
 Appleyard, D., Lynch, K. & Meyer, J.R., The View from the Road, MIT Press: Cambridge,1964.
 Cullen, G., The Concise Townscape, Architectural Press: London, 1976.
 Smardon, R., Castello, T. & Egging, H., Urban visual description and analysis. Foundations for Visual Project Analysis, John Willey & Sons: NY, 1986.
 Smardon, R. & Karp, J., The Legal Landscape, VNR: NY, 1992.