List of fractals by Hausdorff dimension

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A fractal is a geometric object whose Hausdorff dimension (δ) strictly exceeds its topological dimension. Presented here is a list of fractals ordered by increasing Hausdorff dimension, with the purpose of visualizing what it means for a fractal to have a low or a high dimension.

Contents

[edit] Deterministic fractals

δ
(exact value)		 δ
(value)		 Name Illustration Remarks
\textstyle{\frac {ln(2)} {ln(\delta)}?} 0.4498? Logistic equation bifurcations In the bifurcation diagram, when approaching the chaotic zone, a succession of period doubling appears, in a geometric progression tending to 1/δ. (δ=Feigenbaum constant=4.6692).
\textstyle{\frac {ln(2)} {ln(3)}} 0.6309 Cantor set Built by removing the central third at each iteration. Nowhere dense and not a countable set
\textstyle{1} 1 Smith-Volterra-Cantor set Built by removing a central interval of length 1/2^{2n} of each remaining interval at the nth iteration. Nowhere dense but has a Lebesgue measure of ½.
\textstyle{\frac {ln(8)} {ln(7)}} 1.0686 Gosper island
1.26 Hénon map The canonical Hénon map (with parameters a = 1.4 and b = 0.3) has Hausdorff dimension δ = 1.261 ± 0.003. Different parameters yield different δ values.
\textstyle{\frac {ln(4)} {ln(3)}} 1.2619 Von Koch curve 3 von Koch curves form the Koch snowflake or the anti-snowflake.
\textstyle{\frac {ln(4)} {ln(3)}} 1.2619 boundary of Terdragon curve L-system: same as dragon curve with angle=30°. The Fudgeflake is based on 3 initial segments placed in a triangle.
\textstyle{\frac {ln(4)} {ln(3)}} 1.2619 2D Cantor dust Cantor set in 2 dimensions.
1.3057 Apollonian gasket
\textstyle{\frac {ln(5)} {ln(3)}} 1.4649 Box fractal Built by exchanging iteratively each square by a cross of 5 squares.
\textstyle{\frac {ln(5)} {ln(3)}} 1.4649 Quadratic von Koch curve (type 1) One can recognize the pattern of the box fractal (above).
\textstyle{\frac {ln(8)} {ln(4)}} 1.5000 Quadratic von Koch curve (type 2) Also called "Minkowski sausage".
1.5236 Dragon curve boundary Cf Chang & Zhang[1].
\textstyle{\frac {ln(3)} {ln(2)}} 1.5850 3-branches tree Each branch carries 3 branches. (here 90° and 60°). The fractal dimension of the entire tree is the fractal dimension of the terminal branches. NB: the 2-branches tree has a fractal dimension of only 1.
\textstyle{\frac {ln(3)} {ln(2)}} 1.5850 Sierpinski triangle It’s also the triangle of Pascal modulo 2.
\textstyle{\frac {ln(3)} {ln(2)}} 1.5850 Arrowhead Sierpinski curve Same limit as the triangle (above) but built with a one-dimensional curve.
\textstyle{1+log_3(2)} 1.6309 Pascal triangle modulo 3 For a triangle modulo k, if k is prime, the fractal dimension is \scriptstyle{1 + log_k(\frac{k+1}{2})}(Cf Stephen Wolfram [2])
\textstyle{1+log_5(3)} 1.6826 Pascal triangle modulo 5 For a triangle modulo k, if k is prime, the fractal dimension is \scriptstyle{1 + log_k(\frac{k+1}{2})} (Cf Stephen Wolfram [3])
\textstyle{\frac {ln(7)} {ln(3)}} 1.7712 Hexaflake Built by exchanging iterativelly each hexagon by a flake of 7 hexagons. Its boundary is the von Koch flake and contains an infinity of Koch snowflakes (black or white).
\textstyle{\frac {ln(4)} {ln(2(1+cos(85^\circ))}} 1.7848 Von Koch curve 85°, Cesaro fractal Generalizing the von Koch curve with an angle a chosen between 0 and 90°. The fractal dimension is then \scriptstyle{\frac{ln(4)}{ln(2(1+cos(a))}}. The Cesaro fractal is based on this pattern.
\textstyle{\frac {ln(6)} {ln(1+\phi)}} 1.8617 Pentaflake Built by exchanging iteratively each pentagon by a flake of 6 pentagons. φ = golden number = \scriptstyle{\frac{1+\sqrt{5}}{2}}
\textstyle{\frac {ln(8)} {ln(3)}} 1.8928 Sierpinski carpet
\textstyle{\frac {ln(8)} {ln(3)}} 1.8928 3D Cantor dust Cantor set in 3 dimensions.
Estimated 1.9340 Boundary of the Lévy C curve Estimated by Duvall and Keesling (1999). The curve itself has a fractal dimension of 2.
1.974 Penrose tiling See Ramachandrarao, Sinha & Sanyal[4]
\textstyle{2} 2 Mandelbrot set Any plane object containing a disk has Hausdorff dimension δ = 2. However, note that the boundary of the Mandelbrot set also has Hausdorff dimension δ = 2.
\textstyle{2} 2 Sierpiński curve Every Peano curve filling the plane has a Hausdorff dimension of 2.
\textstyle{2} 2 Hilbert curve Built in a similar way: the Moore curve
\textstyle{2} 2 Peano curve And a family of curves built in a similar way, such as the Wunderlich curves.
2 Lebesgue curve or z-order curve Unlike the previous ones this space-filling curve is differentiable almost everywhere. Another type can be defined in 2D. Like the Hilbert Curve it can be extended in 3D[5].
\textstyle{\frac {ln(2)} {ln(\sqrt{2})}} 2 Dragon curve And its boundary has a fractal dimension of 1.5236.
2 Terdragon curve L-System : F-> F+F-F. angle=120°.
\textstyle{\frac {ln(4)} {ln(2)}} 2 T-Square
\textstyle{\frac {ln(4)} {ln(2)}} 2 Gosper curve Its boundary is the Gosper island.
\textstyle{\frac {ln(4)} {ln(2)}} 2 Sierpinski tetrahedron Each tetrahedron is replaced by 4 tetrahedrons.
\textstyle{\frac {ln(4)} {ln(2)}} 2 H-fractal Also the « Mandelbrot tree » which has a similar pattern.
\textstyle{\frac {ln(4)} {ln(2)}} 2 2D greek cross fractal Each segment is replaced by a cross formed by 4 segments.
2.06 Lorenz attractor For precise values of parameters.
\textstyle{\frac {ln(20)} {ln(2+\phi)}} 2.3296 Dodecahedron fractal Each dodecahedron is replaced by 20 dodecahedrons.
\textstyle{\frac {ln(13)} {ln(3)}} 2.3347 3D quadratic Koch surface (type 1) Extension in 3D of the quadratic Koch curve (type 1). The illustration shows the second iteration.
2.4739 Apollonian sphere packing The interstice left by the apollolian spheres. Apollonian gasket in 3D. Dimension calculated by M. Borkovec, W. De Paris, and R. Peikert [6].
\textstyle{\frac {ln(32)} {ln(4)}} 2.50 3D quadratic Koch surface (type 2) Extension in 3D of the quadratic Koch curve (type 2). The illustration shows the first iteration.
\textstyle{\frac {ln(16)} {ln(3)}} 2.5237 Cantor hypercube Cantor set in 4 dimensions. Generalization : in a space of dimension n, the Cantor set has a Hausdorff dimension of \scriptstyle{n\frac{ln(2)}{ln(3)}}
\textstyle{\frac {ln(12)} {ln(1+\phi)}} 2.5819 Icosahedron fractal Each icosahedron is replaced by 12 icosahedrons.
\textstyle{\frac {ln(6)} {ln(2)}} 2.5849 3D greek cross fractal Each segment is replaced by a cross formed by 6 segments.
\textstyle{\frac {ln(6)} {ln(2)}} 2.5849 Octahedron fractal Each octahedron is replaced by 6 octahedrons.
\textstyle{\frac {ln(20)} {ln(3)}} 2.7268 Menger sponge And its surface has a fractal dimension of \scriptstyle{\frac{ln(12)}{ln(3)} = 2.2618}.
\textstyle{\frac {ln(8)} {ln(2)}} 3 3D Hilbert curve A Hilbert curve extended to 3 dimensions.
\textstyle{\frac {ln(8)} {ln(2)}} 3 3D Lebesgue curve A Lebesgue curve extended to 3 dimensions.

[edit] Random and natural fractals

δ
(exact value)		 δ
(value)		 Name Illustration Remarks
Measured 1.24 Coastline of Great Britain
\textstyle{\frac {4}{3}} 1.33 Boundary of Brownian motion (Cf Wendelin Werner)[7].
\textstyle{\frac {4}{3}} 1.33 2D Polymer Similar to the brownian motion in 2D with non self-intersection. (Cf Sapoval).
\textstyle{\frac {4}{3}} 1.33 Percolation front in 2D, Corrosion front in 2D Fractal dimension of the percolation-by-invasion front, at the percolation threshold (59.3%). It’s also the fractal dimension of a stopped corrosion front (Cf Sapoval).
1.40 Clusters of clusters 2D When limited by diffusion, clusters combine progressively to a unique cluster of dimension 1.4. (Cf Sapoval)
Measured 1.52 Coastline of Norway
Measured 1.55 Random walk with no self-intersection Self-avoiding random walk in a square lattice, with a « go-back » routine for avoiding dead ends.
\textstyle{\frac {5} {3}} 1.66 3D Polymer Similar to the brownian motion in a cubic lattice, but without self-intersection (Cf Sapoval).
1.70 2D DLA Cluster In 2 dimensions, clusters formed by diffusion-limited aggregation, have a fractal dimension of around 1.70 (Cf Sapoval).
\textstyle{\frac {91} {48}} 1.8958 2D Percolation cluster Under the percolation threshold (59.3%) the percolation-by-invasion cluster has a fractal dimension of 91/48 (Cf Sapoval). Beyond that threshold, le cluster is infinite and 91/48 becomes the fractal dimension of the « clearings ».
\textstyle{\frac {ln(2)} {ln(\sqrt{2})}} 2 Brownian motion Or random walk. The Hausdorff dimensions equals 2 in 2D, in 3D and in all greater dimensions (K.Falconer "The geometry of fractal sets").
\textstyle{\frac {ln(13)} {ln(3)}} 2.33 Cauliflower Every branch carries around 13 branches 3 times smaller.
2.5 Balls of crumpled paper When crumpling sheets of different sizes but made of the same type of paper and with the same aspect ratio (for example, different sizes in the ISO 216 A series), then the diameter of the balls so obtained elevated to a non-integer exponent between 2 and 3 will be approximately proportional to the area of the sheets from which the balls have been made. [1] Creases will form at all size scales (see Universality (dynamical systems)).
2.50 3D DLA Cluster In 3 dimensions, clusters formed by diffusion-limited aggregation, have a fractal dimension of around 2.50 (Cf Sapoval).
Measured 2.66 Broccoli [8]
2.79 Surface of human brain [9]
2.97 Lung surface The alveoli of a lung form a fractal surface close to 3 (Cf Sapoval).

[edit] References

  1. ^ Fractal dimension of the boundary of the dragon fractal
  2. ^ Fractal dimension of the Pascal triangle modulo k
  3. ^ Fractal dimension of the Pascal triangle modulo k
  4. ^ Fractal dimension of a penrose tiling
  5. ^ Lebesgue curve variants
  6. ^ Fractal dimension of the apollonian sphere packing
  7. ^ Fractal dimension of the brownian motion boundary
  8. ^ Fractal dimension of the broccoli
  9. ^ Fractal dimension of the surface of the human brain

[edit] See also

[edit] Bibliography

  • 1Kenneth Falconer, Fractal Geometry, John Wiley & Son Ltd; ISBN 0-471-92287-0 (March 1990)
  • Benoît Mandelbrot, The Fractal Geometry of Nature, W. H. Freeman & Co; ISBN 0-7167-1186-9 (September 1982).
  • Heinz-Otto Peitgen, The Science of Fractal Images, Dietmar Saupe (editor), Springer Verlag, ISBN 0-387-96608-0 (August 1988)
  • Michael F. Barnsley, Fractals Everywhere, Morgan Kaufmann; ISBN 0-12-079061-0
  • Bernard Sapoval, « Universalités et fractales », collection Champs, Flammarion.

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