The degree of visibility as a tool to assess and design of a visual corridor
Author
Forczek-Brataniec, Urszula
Co-author
Szent István University. Department of Landscape Planning and Regional Development [org.] University of Massachusetts Amherst. Department of Landscape Architecture and Regional Planning [org.]
Published in
Greenways and Landscapes in Change : proceedings of 5th Fábos Conference on Landscape and Greenway Planning (Budapest, 30 June, 2016) / ed. by Valánszki, István; Jombach, Sándor; Filep-Kovács, Krisztina; Fábos, Julius Gy. ; Ryan, Robert L.; Lindhult, Mark S.; Kollányi, László
Numbering
1
Pages
295-302
Release date
2016
Place of publication
Budapest
Publisher
Szent István University. Department of Landscape Planning and Regional Development. University of Massachusetts Amherst. Department of Landscape Architecture and Regional Planning
Visibility field lies at the core of the contemporary visual analysis. On the basis of the digital land model we define the area which is spatially influenced by a given implementation and area remaining in the visual shade (Bishop & Miller 2007, Watson 2013, Ozimek & Ozimek 2008). This information is key for all types of studies on visual impact of the investment on landscape as well as on landscape design being closely related to the shape of the surrounding. In case of linear elements, such as roads, power lines, river corridors, the designated visibility field turns out to be merely partial information about its real visual characteristics since the linear element is a complex structure and its particular parts are characterised by diversified visibility range. Shall we assume that the line comprises points in the right order, then it might be stated that they have individual visual range originating from their location. Putting together visibility fields of particular points helps to build a multilayered visibility field that describes the line. This complex visibility field becomes a source of precise information that creates a bigger picture of real spatial features of the linear element. In order to examine the multilayered spatial field a model situation was set up to enable formulating preliminary results. The next step involved application of the results in the selected spatial situation. The simplified spatial model consisted of the sculpted surface of the base, lines, and control cameras. A multilayered visibility field was created as a result of the studies of particular line points. The analysis of the visibility field structure led to singling out the areas of various layers of component fields. Threshold differentiation of areas in terms of the number of layers allowed to specify the degree of visibility of the given area. The visibility degree was given a numeric value in the form of percentages as well as a graphical record in the form of visibility spirit levels. Features of visibility fields which have been set out in this way highlighted the areas of highest and lowest intensity of exposure. The area visible from all the points (of the whole line section analysed) gained 100% of exposure degree whereas the area which was not visible from any of the points received 0% of visibility degree. At the same time the area visible from a half of the section of the analysed line was given 50% of exposure degree. The above mentioned results of the study were applied to analyze exposure of a road section in the Bieszczady National Park (Forczek-Brataniec, Nosalska 2010). Application of this method with use of visibility degree allowed for precise characteristics of the area in terms of its impact on the visual corridor of the road. The areas of the highest visual influence were singled out and possibilities for visual improvement regarding exposure quality were defined. There are considerable possibilities of applying this method. It might act as an assistant in describing visual characteristics of a given linear element as well as studying its transformations. The data concerning the visibility degree in case of the linear structure is extremely crucial. The dimensional visibility field which is most often applied helped to shed some light on the dilemma regarding the visibility or lack of visibility of a given area from the road. The analysis of the visibility field structure let us answer the question regarding the part of the road where a given area is visible. Hence, we are given the opportunity to recognize the real visual role it plays in the area of the visual corridor. The presented method is in line with the commonly applied method of the visual impact assessment method while it takes a step forward in terms of studying the visibility field (BLM Manuals, GLVIA 2002).
