ssToroid: Toroidal boundary correction for "sampSurf" Objects

In ssWavelets: Wavelet Functionality for Package 'sampSurf'

Description

This routine takes a “sampSurf” object and makes a larger “Raster” object with copies of the original all around it using toroidal correction, more commonly called periodization or circular correction for the boundary.

Toroidal correction is specifically used for correction of “edge effect” in the application of a MODWT wavelet filter as discussed in detail in Lark and Webster (2004); see details below.

Usage

ssToroid(ss, ...)

Arguments

ss	An object of class “sampSurf”.
...	Gobbled.

Details

This method is meant to be used stand-alone as an illustration for what happens in periodic correction. An example is given below, and a more extensive discussion can be found in the package vignette.

It should be kept in mind that the ssMODWT constructor uses the waveslim code for the decomposition. This code always applies a periodic correction to the image. Therefore, there is no need to use this routine for this type of correction when creating objects of class “ssMODWT”.

I suppose this could be used in sampSurf proper as a boundary correction technique for inclusion zones. Perhaps some version of it will make its way into that package in the future to compliment those boundary correction methods already available.

Value

A “Raster” image padded in all directions using the toriodal correction.

Author(s)

Jeffrey H. Gove

References

R. M. Lark and R. Webster. 2004. Analysing soil variation in two dimensions with the discrete wavelet transform. European Journal of Soil Science, 55:777–797.

See Also

ssReflect

Examples

#
# creates a sampSurf object with horizontal point sampling
# then does a toroidal correction...
#
tr = Tract(c(x = 64, y = 64), cellSize = 1) #square tract ~0.5ha
btr = bufferedTract(10, tr)
ag3m = angleGauge(3)        #metric BAF
sshps = sampSurf(10, btr, iZone = 'horizontalPointIZ', angleGauge = ag3m,
        topDiam = c(0,0), startSeed = 123)
torhps = ssToroid(sshps)    #raster object
## Not run: 
plot(torhps, col = palMODWT(100, range=cellStats(torhps, range)))
plot(perimeter(sshps), add = TRUE)

## End(Not run)

ssWavelets documentation built on May 2, 2019, 5:54 p.m.