# heather

##### Diggle's Heather Data

The spatial mosaic of vegetation of the heather plant
(*Calluna vulgaris*) recorded in a 10 by 20 metre
sampling plot in Sweden.

##### Usage

`data(heather)`

##### format

A list with three entries, representing the same data at
different spatial resolutions:
`coarse`

original heather data, 100 by 200 pixels
`medium`

current heather data, 256 by 512 pixels
`fine`

finest resolution data, 778 by 1570 pixels
}
Each of these entries is an object of class `"owin"`

containing a binary pixel mask.

##### source

Peter Diggle

##### History of analysis of data

The data were recorded, presented and analysed by Diggle (1983). He proposed a Boolean model consisting of discs of random size with centres generated by of a Poisson point process. Renshaw and Ford (1983) reported that spectral analysis of the data suggested the presence of strong row and column effects. However, this may have been attributable to errors in the run-length encoding of the original data.

Hall (1985) and Hall (1988, pp 301-318) took a bootstrap approach.

Ripley (1988, pp. 121-122, 131-135] used opening and closing functions to argue that a Boolean model of discs is inappropriate.

Cressie (1991, pp. 763-770) tried a more general Boolean model.

##### References

Cressie, N.A.C. (1991)
*Statistics for Spatial Data*.
John Wiley and Sons, New York.

Diggle, P.J. (1981)
Binary mosaics and the spatial pattern of heather.
*Biometrics* **37**, 531-539.

Hall, P. (1985)
Resampling a coverage pattern.
*Stochastic Processes and their Applications*
**20** 231-246.

Hall, P. (1988)
*An introduction to the theory of coverage processes*.
John Wiley and Sons, New York.

Renshaw, E. and Ford, E.D. (1983)
The interpretation of process from pattern using
two-dimensional spectral analysis: Methods and
problems of interpretation. *Applied Statistics* **32** 51-63.
Ripley, B.D. (1988)
*Statistical Inference for Spatial Processes*.
Cambridge University Press.

*Documentation reproduced from package spatstat, version 1.21-0, License: GPL (>= 2)*