90
9) The View tab allows the user to see or set the latitude/longitude, range, heading, tilt and date/time however this is not available to polygons, only points. 10) The Altitude tab allows the user to decide the altitude of the polygon. 11) Create the building footprint-‐polygon by left clicking on the map along a corner of the roof. Space between nodes will be drawn as a straight line, so clicks are only necessary where a change in the direction of the border occurs. Note: Imagery in Google Earth is often angled so that rooflines will often be off to a side of the foundation structure. Only follow the roofline when creating the footprint to avoid getting an incorrect area computation later. See figure 5.47.
Figure 5.47 Building footprint delineation along roofline.
12) Include only structural aspects of the building in the footprints. When shadows and trees obscure the view, try to follow the proportion and shape of the building parts that are visible to make the best estimate. Note: Some buildings have multiple areas that jut out. Try to get the entire area, but being perfect is not necessary Note: Do not include courtyards in building footprints (figure 5.48)