Terms now commonly
applied to the computer prediction of visibility of a proposed development... most often
required by planning authorities as standard baseline studies for planning applications at
all scales of development:
ZVI - 'Zones of Visual
Influence' is generally
accepted as the 'bare-earth' or 'worst case' scenario, upon which the visibility is
calculated... always a good starting point for desktop study of Landscape Visual Impact
Assessment (LVIA)
ZTV - 'Zones of Theoretical
Visibility' is becoming
more commonly used to describe the potential visual influence of a development in the
context of the surrounding environment, as predicted by computer analysis. Data for
surrounding building and woodland heights is input and their screening effect can be
demonstrated by comparison of the visibility results with the bare-earth ZVI
In either of these types of
analysis, the results can be represented most effectively in the following ways:
- a simple 'count' of visible points... suitable for turbines in a wind farm
for example or lighting columns in a park and ride facility
- a colour banded plan in which the magnitude of visibility can be
displayed... this can be the actual vertical heights of a proposed building visible, or
the 'subtended angle' visible in the vertical field of view of the observer (please call
and we'll explain!)
Landscape Visual Capacity to accommodate new development is a relatively
new process whereby we can 'contour' the landform to predict the maximum height of new
development that will not be seen from key sensitive areas - such as conservation areas or
historic landscapes
