Rhombic dodecahedral honeycomb
Rhombic dodecahedral honeycomb | |
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Type | convex uniform honeycomb dual |
Coxeter-Dynkin diagram | ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
Cell type | ![]() Rhombic dodecahedron V3.4.3.4 |
Face types | Rhombus |
Space group | Fm3m (225) |
Coxeter notation | ½, [1+,4,3,4] , [4,31,1] ×2, <[3[4]]> |
Dual | tetrahedral-octahedral honeycomb |
Properties | edge-transitive, face-transitive, cell-transitive |
The rhombic dodecahedral honeycomb (also dodecahedrille) is a space-filling tessellation (or honeycomb) in Euclidean 3-space. It is the Voronoi diagram of the face-centered cubic sphere-packing, which has the densest possible packing of equal spheres in ordinary space (see Kepler conjecture).
Geometry
It consists of copies of a single cell, the rhombic dodecahedron. All faces are rhombi, with diagonals in the ratio 1:√2. Three cells meet at each edge. The honeycomb is thus cell-transitive, face-transitive, and edge-transitive; but it is not vertex-transitive, as it has two kinds of vertex. The vertices with the obtuse rhombic face angles have 4 cells. The vertices with the acute rhombic face angles have 6 cells.
The rhombic dodecahedron can be twisted on one of its hexagonal cross-sections to form a trapezo-rhombic dodecahedron, which is the cell of a somewhat similar tessellation, the Voronoi diagram of hexagonal close-packing.
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![]() The honeycomb can be derived from an alternate cube tessellation by augmenting each face of each cube with a pyramid. |
![]() The view from inside the rhombic dodecahedral honeycomb. |
Colorings
Cells can be given 4 colors in square layers of 2-colors where neighboring cells have different colors, and 6 colors in hexagonal layers of 3 colors where same-colored cells have no contact at all.
4-colors | 6-colors |
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Alternate square layers yellow, blue with red and green | Alternate hexagonal layers of red,green,blue and magenta, yellow, cyan. |
Related honeycombs
The rhombic dodecahedral honeycomb can be dissected into a trigonal trapezohedral honeycomb with each rhombic dodecahedron dissected into 4 trigonal trapezohedrons. Each rhombic dodecahedra can also be dissected with a center point into 12 rhombic pyramids of the rhombic pyramidal honeycomb.
Trapezo-rhombic dodecahedral honeycomb
Trapezo-rhombic dodecahedral honeycomb | |
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Type | convex uniform honeycomb dual |
Cell type | trapezo-rhombic dodecahedron VG3.4.3.4![]() |
Face types | rhombus, trapezoid |
Symmetry group | P63/mmc |
Dual | gyrated tetrahedral-octahedral honeycomb |
Properties | edge-uniform, face-uniform, cell-uniform |
The trapezo-rhombic dodecahedral honeycomb is a space-filling tessellation (or honeycomb) in Euclidean 3-space. It consists of copies of a single cell, the trapezo-rhombic dodecahedron. It is similar to the higher symmetric rhombic dodecahedral honeycomb which has all 12 faces as rhombi.
Related honeycombs
It is a dual to the vertex-transitive gyrated tetrahedral-octahedral honeycomb.
Rhombic pyramidal honeycomb
Rhombic pyramidal honeycomb | |
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(No image) | |
Type | Dual uniform honeycomb |
Coxeter-Dynkin diagrams | ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
Cell | ![]() rhombic pyramid |
Faces | Rhombus Triangle |
Coxeter groups | [4,31,1], [3[4]], |
Symmetry group | Fm3m (225) |
vertex figures | ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
Dual | Cantic cubic honeycomb |
Properties | Cell-transitive |
The rhombic pyramidal honeycomb or half oblate octahedrille is a uniform space-filling tessellation (or honeycomb) in Euclidean 3-space.
This honeycomb can be seen as a rhombic dodecahedral honeycomb, with the rhombic dodecahedra dissected with its center into 12 rhombic pyramids.
![]() rhombic dodecahedral honeycomb |
![]() Rhombohedral dissection |
![]() Within a cube |
Related honeycombs
It is dual to the cantic cubic honeycomb:
See also
References
- Williams, Robert (1979). The Geometrical Foundation of Natural Structure: A Source Book of Design. Dover Publications, Inc. p. 168. ISBN 0-486-23729-X.
External links
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