Determination of thresholds of visual impact: the case of wind turbines.
Ian D. Bishop
Centre for Geographic Information Systems and Modelling
The University of Melbourne, 3010 Australia
idbishop@unimelb.edu.au

Environment and Planning B: Planning and Design 29, 707-718

ABSTRACT
Visual impact assessment using GIS based viewshed mapping is commonly employed on major projects. However, there is typically little analysis of the possible range of impact based on the size of the introduced landscape element, its contrast with the surroundings or the effect of typical level of atmospheric scattering on the perceived contrast. A landscape element which is increasingly the subject of aesthetic scrutiny and visual analysis is the wind energy turbine or - when installed in large numbers - the wind-farm. This paper takes the wind turbine as its subject partly because of its recent significance and also because, as a moving element, it is a special case. The paper reports an Internet based experiment to determine the relative perceived size of a turbine, image analysis to determine its typical contrast level and the effect of atmospheric scattering on this contrast. Using these three factors and equations derived in an earlier study (Shang & Bishop, 2000), estimates are made for the probability of turbine detection, recognition and visual impact at distances up to 30 km.

KEYWORDS
Visual thresholds, wind turbines, visual impact.

http://www.sli.unimelb.edu.au/envis/windmills/survey_page.html