Sand particle outline data
50 points on 24 sea sand and 25 river sand grain profiles in 2D. The original data were kindly provided by Professor Dietrich Stoyan (Stoyan and Stoyan, 1994; Stoyan, 1997). The 50 points on each outline were extracted at approximately equal arc-lengths by the method described in Kent et al. (2000, section 8.1)
data(sand)
A list with components:
sea$x : An array of dimension 50 x 2 x 49 containing the 50 point co-ordinates in 2D for each grain
sea$group : The types of the sand grains: "sea", 24 particles from the Baltic Sea
"river", 25 particles from the Caucasian River Selenchuk
Kent, J. T., Dryden, I. L. and Anderson, C. R. (2000). Using circulant symmetry to model featureless objects. Biometrika, 87, 527–544.
Stoyan, D. (1997). Geometrical means, medians and variances for samples of particles. Particle Particle Syst. Charact. 14, 30–34.
Stoyan, D. and Stoyan, H. (1994). Fractals, Random Shapes and Point Fields: Methods of Geometric Statistics, John Wiley, Chichester.
data(sand) plotshapes(sand$x[,,sand$group=="sea"],sand$x[,,sand$group=="river"],joinline=c(1:50))
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