Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
Newlyn. In reality, the earth is round, so a correction has to be made in order to position
geographical features correctly in three dimensions for ZTV calculation and for visualisation”
and “In the absence of the Earth’s atmosphere, a simple allowance for curvature would be
sufficient”… “in the practice, rays of light representing sightlines over long distances are also
curved downwards, allowing one to see slightly beyond the expected horizon.”
9.3.50 The distance from some viewing points to the turbines means that the limitations of normal
sight would also affect visibility, as explained below.
Acuity of Eye
9.3.51 The Guide to Best Practice in Seascape Assessment (GSA) discusses the limitations of the
acuity of the human eye on an object similar to that of a turbine. The guidance (para. 2.4
Difficulties of scale and distance) states that: “At a distance of 1 kilometre in conditions of good
visibility a pole of 100mm diameter will become difficult to see, and at 2 kilometres a pole of
200mm diameter will similarly be difficult to see. In other words there will be a point where an
object whilst still theoretically visible will become too small for the human eye to resolve. Mist,
haze or other atmospheric conditions may significantly exacerbate that difficulty.”
Consequently when visible in favourable conditions, a slim object approximately 3m in width
will be at the limit of perception by the human eye at a distance of 30km.
Principal Visual Receptors and Representative Viewpoints
9.3.52 The landscape and visual amenity of the study area was surveyed to establish the general
characteristics of both static and dynamic views, from a selection of receptors likely to
experience views of the proposed wind energy development.
9.3.53 Visual effects are those changes to views that result from the proposed wind energy
development. The evaluation of views is carried out in two parts:
• the potential views from principal visual receptors, which are the settlements and
routes found throughout the study area; and
• the potential views from a series of viewpoints that have been selected to represent
visibility from around the study area.
9.3.54 The assessment of effects on principal visual receptors and representative viewpoints is
presented in section 9.4 ‘Assessment of Effects’.
Settlements and Road Network
9.3.55 There are a number of settlements and travel routes in the study area that need to be identified
and considered in the assessment as views from them may be affected by the wind energy
development. These features are referred to as ‘principal visual receptors’ in the assessment.
The principal visual receptors and the basis for their inclusion are described briefly below.
9.3.56 The size and distribution of settlements varies throughout the study area. The pattern of
settlement across the study area closely follows the topography, with larger and more frequent
November 2010 Chapter 9 Page 34
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