Calculate and display Ptolemaic ellipses which illustrates intuitively the principle behing elliptical Fourier analysis.
Usage
Ptolemy(
coo,
t = seq(0, 2 * pi, length = 7)[-1],
nb.h = 3,
nb.pts = 360,
palette = col_heat,
zoom = 5/4,
legend = TRUE,
...
)
Arguments
- coo
a matrix of (x; y) coordinates
- t
A
vector
af angles (in radians) on which to display ellipses- nb.h
integer
. The number of harmonics to display- nb.pts
integer
. The number of points to use to display shapes- palette
a color palette
- zoom
numeric a zoom factor for coo_plot
- legend
logical
. Whether to plot the legend box- ...
additional parameters to feed coo_plot
References
This method has been inspired by the figures found in the followings papers. Kuhl FP, Giardina CR. 1982. Elliptic Fourier features of a closed contour. Computer Graphics and Image Processing 18: 236-258. Crampton JS. 1995. Elliptical Fourier shape analysis of fossil bivalves: some practical considerations. Lethaia 28: 179-186.
See also
An intuitive explanation of elliptic Fourier analysis can be found in the Details section of the efourier function.
exemplifying functions