Geographical analysis and Geographical analysis and numerical - PowerPoint PPT Presentation

Geographical analysis and Geographical analysis and numerical quantification numerical quantification of visual impact for aerogenerators of visual impact for aerogenerators and photovoltaic panels and photovoltaic panels using Open Source GIS using Open Source GIS A. Minelli, A. Minelli, I. Marchesini, I. Marchesini, P. De Rosa, L. Casagrande & M. Cenci P. De Rosa, L. Casagrande & M. Cenci Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Sun and wind farm: the visual impact Sun and wind farm: the visual impact It seems the heaviest to most of the people Is it possible to quantify it? Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Visibility quantification Visibility quantification To quantitatively define the visual impact we developed a GRASS GIS module: module: GRASS GIS r.wind.sun r.wind.sun Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: Input Aerogenerators: Input DEM Vector layer of aerogenerators position Heigth of the aerogenerators Computational distance Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Photovoltaic panels: input Photovoltaic panels: input DEM Vector layer of panels position (centroid) Vertical dimension of the single panel Horizontal dimension of the single panel Inclination of panel Azimuth of the panel Panel height above the ground Minimum computational distance Maximum computational distance Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

The impact index The impact index I = A obj A FOV I = impact index (relative size of the object) A obj = distorted object size A FOV = observers' Field Of View Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Static Field Of View Static Field Of View We define the static FOV as an ellipsoidal, three-axes, shape The dimensions of the FOV axes depends on: ● the distance “ d ” ( from the observer) at which FOV is calculated ● three angles: d - Nose se = = 85° - Superio ior = = 6 65° - In Infe ferior = r = 7 70° s=d*tg(65°) n=d*tg(85°) i=d*tg(70°) Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Dynamic Field Of View Dynamic Field Of View First approach: from his point of view the observer can rotate his view all around 360° Height: h= (s+i) Circumference: l=2πd Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Dynamic Field Of View Dynamic Field Of View The dynamic FOV is the internal area of a cylinder: I*h . l=2πd h= (s+i) This approach is adopted to calculate the FOV for the assessment of the visual impact due to the photovoltaic panels Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Dynamic Field Of View Dynamic Field Of View Second approach: from his point of view the observer can both rotate his view all around 360° and look up and down The dynamic FOV area is the area of a sphere: A=4πd 2 . Since both horizontal and vertical dimension of the aerogenerators are not negligible, this approach is adopted to estimate FOV for the assessment of the aerogenerators visual impact Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Perceived shape and size Perceived shape and size Fixing a proje jecti tive p pla lane Π , the relative size and shape ( red line ) depends on: ● the distance (d) between the object and the observer; ● the mutual observer – object height ( ∆ h) . d Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Perceived shape and size Perceived shape and size In general, the projecti tive p pla lane Π can also be placed at a distance r != d . In that case the field of view is also estimated at the distance “r”. In that way the ratio between field of view and the object size is maintained constant r d Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size An aerogenerator has a quite complex shape. In order to simplify the analysis, the area covered by the rotor is considered completely filled. Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size Two components are considered separately: tower and rotor rotor The size becomes the sum of the areas of a trapezius tower (tower) and an ellipse In fact the rotor vertical axis is quite ever deformed from the point of view of the observer Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size If the aerogenerator is fully visible: the center of view (red point) is placed between the rotor and the tower Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size The length of vertic ical a axis is of th the e ell llip ipse and the heig igth th o of t f the trapezium are calculated tr Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size Since the aerogenerator rotor can turn (to be ever perpendicular to the main wind direction), the width of the rotor ellipse is, conservatively, not altered Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size If the terrain hides a large part of the tower: the tower is not considered for the analysis Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Aerogenerators: perceived shape and size Aerogenerators: perceived shape and size If the terrain covers up also part of the rotor: only half of the rotor area is considered Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Single Aerogenerator: Impact index Single Aerogenerator: Impact index Considering a single aerogenerator, it is possible (using a DEM) to evaluate the Impact Index map. For each point (raster cell) of the surrounding area: I = A obj A FOV Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Multiple aerogenerators: Impact Index Multiple aerogenerators: Impact Index The Impact Index apply also in case of multiple aerogenerators I = ∑ A obj A FOV Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Photovoltaic panels: perceived shape and size Photovoltaic panels: perceived shape and size The problem of relative shape and size change also apply to the Photovoltaic Panels. The size an shape change both vertically …...... and horizontally Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Photovoltaic panels: perceived shape and size Photovoltaic panels: perceived shape and size Fortunately the distorted shape of a rectangle is a parallelogram or a trapezium, so it is easy to calculate its the area. Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

Photovoltaic panels: Impact Index Photovoltaic panels: Impact Index The Impact Index must be calculated for each panel or group of panels. I = ∑ A obj A FOV Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

r.wind.sun: results r.wind.sun: results The r.wind.sun output is a raster layers of the sum of the impact index calculated for each photovoltaic panel or aerogenerator Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

r.wind.sun: results r.wind.sun: results Generally speaking the value of each cell represents the occupancy, of the field of view, determined by the presence of all the aerogenerators or photovoltaic panels Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

r.wind.sun: results r.wind.sun: results The raster layers can be reclassified to be easily interpreted. Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

r.wind.sun: results r.wind.sun: results Aerogenerators The 3D visualization allows to highlight the effect of the partial 1 hiddenness, due to the 2 terrain, of the 3 aerogenerators 4 1=low impact 5 … 6 … 6=high impact 2 3 4 The Impact Index values decrease towards the 3 aerogenerators 2 Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato

r.wind.sun: results r.wind.sun: results Moreover, by means of the GRASS GIS nviz tool, the r.wind.sun module allows for a 3D view of the aerogenerators Regione Gfosservices Regione Gfosservices Umbria Studio Associato Umbria Studio Associato