DOME GEOM

GEODESIC DOMES

THE GEOMETRY




DOMES ARE PARTS OF SPHERES


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Geodesic domes are fractional parts of complete geodesic spheres. Actual structures range from less than 5% to 100% (a full sphere). The Spaceship Earth Pavilion constructed by Tishman Construction for AT&T at Disney's Epcot is the best-known example of a full sphere.




DOMES HAVE VARIOUS FREQUENCIES


Geodesic spheres and domes come in various frequencies. The frequency of a dome relates to the number of smaller triangles into which it is subdivided. A high frequency dome has more triangular components and is more smoothly curved and sphere-like. If your web browser is Java-enabled, you can interact with the exhibit on Frequency at right.

Picture of Applet



DOMES RELATE TO SPHERE PACKING

Fuller realized that spheres packed around a nuclear sphere in successive layers give a cuboctahedral shape, which may be distorted into an icosahedron or octahedron via what he called the jitterbug transformation.


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animated GIF by Richard Hawkins

The network of rods between adjacent spheres in a hollow icosahedral packing gives the framework for the classic geodesic sphere. Geodesic domes may also be based on other polyhedra, such as the octahedron and tetrahedron.


image 5-frequency

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9-frequency




DOMES COME IN CLASSES


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Class I
3freq

The classic geodesic sphere is composed of 20 curved triangles, each of which corresponds to one facet of the icosahedron, a 20-faceted polyhedron. Each of the 20 triangles is curved because it is subdivided into smaller triangles, the corners of which are all pushed out to a constant distance from the sphere's center. The pattern used for this subdividing into smaller triangles is used to classify domes into classes I, II and III.


For further reading

Domes | History | Geometry | Providers | Prototypes


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