Environmental Engineering Reference
of a landscape can be analysed according to three organisation levels: an objective
dimension (formal landscape organisation, proportion, composition rhythm of
various biophysical elements), a cultural dimension (related to social groups, to history,
to representations of nature), and an individual subjective dimension (Sauget and
Depuy 1996) . Some socio-economists have undertaken to assign values to the aesthetics
of a landscape (Thomas and Price 1999) , but this subjective dimension generally
leads land managers to seek a consensus between stakeholders, by negotiating around
some kind of visual representation (Tyrväinen and Tahvanainen 2000) .
Representing a landscape has always been a difficult task. As early as the sixteenth
century, “bird's-eye” views sought to combine two-dimensional maps with a
representation of perspective. Nowadays, land managers have a number of tools at
their disposal (Perrin et al. 2001) .
Maps and plans have often been - and still are - used for their rigour and for the
possibility of quantification they offer.
Their use is now greatly facilitated by geographic information systems (GIS).
These computer tools include georeferenced databases, which help to produce
two-dimensional maps. They contain large amounts of information, which can
help to represent land-use and its evolution. GIS manufacturers provide
three-dimensional visualisation techniques, which however remain too restrictive
to represent satisfactorily large landscapes: the terrain is generally well represented,
but particular landscape features and architectural elements are often simply
extruded, and do not represent real volumes.
Photographs can be used directly, or can be modified with the help of computer-aided
imagery. This technique has been used for example by Tress and Tress (2003) to
discuss various scenarios with stakeholders. It is however very time-consuming
to build different scenarios of future land-use.
Schematic representations can be produced simply by drawing sketches or
diagrams, either by hand or with the help of computer systems.
Photographs and drawings have no direct link with maps, and only show a limited
number of viewpoints. They are purely visual techniques, which cannot easily
simulate the reactions of a landscape to human interventions.
Virtual imagery is a modern tool which can help represent landscapes, in three
dimensions, and which can also provide the possibility to include a dynamic aspect.
Three-dimensional visualisation of the landscape provides means that are better
understood than maps, especially for the general public. With such methods, visual
changes of the landscape can be shown very impressively, which can allow for an
intuitive assessment of the visual landscape quality.
Static, web-based landscape visualisation tools have made considerable progress
the entire planet in 3D. The French geographic service proposes Géoportail
( http://www.geoportail.fr/ ), a tool which couples 3D visualisation with a number
of additional GIS layers, such as high quality maps, as well as extruded buildings.
A number of companies offer facilities for creating and customizing maps and
virtual visits, such as the Microsoft product Virtual Earth 3D, a plug-in for 3D