Chapter 17 — History and Planning with Google Earth 339
The key element is how the location of the overlay is associated with the map. The north,
south,east, and westelements set the borders of the image as it will be associated on the
map. The other elements are as follows:
Icon:Defines the overlay image.
viewBoundScale:Specifies how much of the display real estate should be used to
show the overlay.
Color:Specifies the color and opacity of the overlay. The color is specified as four two-
character hexadecimal values, between 0 and 255. The first value is the alpha (opacity)
channel. The value specified in this case is 77 (hex), or 119 decimal, or about 47 percent.Although the information displayed is useful, with a 3D environment it would be much better
to give a proper 3D representation of the offices.
Creating a 3D Structure
To create a 3D structure, for example, the representation of an office, you combine latitude/
longitude references with extrusion and altitude to generate a “solid” 3D object on the map.
The key is the Polygonelement, a base structure that defines a simple multi-point shape
made up of the lines that connect latitude/longitude points. Without extrusion, a Polygon
would draw a simple shape. With extrusion and altitude you solidify the polygon. The basic
structure for a polygon is as follows:
-97.59277582168579, 35.282008632343754,100
-97.59277582168579, 35.278137436300966,100
-97.59017944335938, 35.278137436300966,100
-97.59017944335938, 35.282008632343754,100
-97.59277582168579, 35.282008632343754,100