Uruguay es uno de los países de la región que presenta un avance en su IDD-Lat con

Figure 27: The effect of earth curvature on wireline composition

This hill should actually be over the horizon and not visible

important to bear in mind that a planar perspective is not the same as a panorama (there is more detail on this topic in Appendix B). Panoramas can always be approximated with software like this by generating a series of panels that approximate to the required perspective, and then splicing them together in the way that would be done with photographs.

194 Software packages designed for depicting areas of terrain usually include the effect of earth curvature, whereas general-purpose CAD packages most often do not. As pointed out in paragraph 50, the effect of earth curvature increases rapidly with distance from the viewpoint and has a profound effect on the resulting view (figure 27). Wirelines constructed without earth curvature will at best be a poor match to photographs, and at worst will be seriously

misleading, as they show features in the distance which in reality would be hidden below the horizon (see Appendix F).

Drawing style

195 Wirelines consist of little more than simple line- drawings of the DTM and the windfarm. However, there are a range of graphic styles used to depict these which can affect the clarity and legibility of the finished image. A number of options are acceptable; however it is important that the same format is used within a single ES.

196 The DTM is most commonly drawn as a mesh seen in perspective. While this is a faithful depiction of the landform as represented by the DTM, it can often result in the more distant parts of the scene becoming unreadable as the grid lines get closer together, eventually merging into solid colour. An alternative, offered by some packages, is to draw only the outline of the topographic features in the scene,

approximating to the lines one might draw as a sketch of the scene (figures 28a and 28b). While this

similar to that which might be hand drawn by a landscape architect or experienced specialist assessor, it can sometimes make the shape of some features harder to understand in three dimensions. A few packages offer a further option of drawing the outlines and also putting in the mesh in a different colour or lighter shade. While the options available within separate software packages may limit choice, it is worthwhile trying alternatives to see which works best for a particular project.

197 Colour is useful to highlight the wind turbines in contrast to the landform lines or mesh, especially in distant views where the effect of merging lines noted above often occurs and where some turbines may only just be visible against the landform. It is sometimes argued that this unnecessarily draws attention to the windfarm but, as the purpose of the diagram is to depict the geometrical relationship between the windfarm and landform, this is not a compelling argument. There are a number of options, such as those listed below and shown in figures 28a and28b.

• Green turbines on a black DTM;

• Red turbines on a black DTM;

• Black turbines on a grey DTM;

• Blue turbines on a grey DTM; and

• Grey turbines on a green DTM.

198 Using the same colour and/or shade for the turbines and DTM grid is not recommended due to the lack of distinction between them, as already discussed. However, all the other options listed above, and potentially others too, are acceptable with the caveat that care must be taken to ensure that the type of colouring does not produce an illusion that the turbines are closer than the landform on which they are sited.

199 Varying colours of turbines can be used to distinguish separate windfarms within a view or existing turbines from proposed wind turbines planned as an extension.

200 Turbines can also be numbered, as mentioned in paragraph 188, so that the individual turbines visible can be directly referred to a layout plan also showing turbines numbered. Unless the windfarm is a very small development, however, this information will usually take up a large amount of space upon the wireline image and, similar to any other labelling, may reduce clarity and distract from the wireline image itself. Consequently, it is generally preferable to label duplicate wirelines within an appendix (just a selection of key viewpoints may suffice). This labelling may need to be done manually, depending on the software used.

201 Features other than wind turbines, can also be

modelled into the wireline, depending on the software being used. In this way, existing landscape features can be shown, such as pylons or distinctive buildings, which will help direct comparison with the photograph of the existing view (as long as these do not obscure the wind turbines). In addition, other elements of the windfarm development can be shown, such as the route of access tracks. Inclusion of reference objects, such as field boundaries can help the process of matching the perspective and the photograph during photomontage preparation (although these will usually not be desired in the final wireline used in the ES).