tpsgrid {shapes}R Documentation

Thin-plate spline transformation grids

Description

Thin-plate spline transformation grids from one planar object to another. A square grid on the first object is deformed smoothly using a pair of thin-plate splines to a curved grid on the second object.

Usage

tpsgrid(TT, YY, xbegin=-999, ybegin=-999, xwidth=-999, opt=2, ext, ngrid, cex=1, pch, col=2)

Arguments

TT First object (source): (k x 2 matrix)
YY Second object (target): (k x 2 matrix)
xbegin lowest x value for plot: if -999 then a value is determined
ybegin lowest y value for plot: if -999 then a value is determined
xwidth width of plot: if -999 then a value is determined
opt Option 1: (just deformed grid on YY is displayed), option 2: both grids are displayed
ext Amount that grid extends over object.
ngrid Number of grid points: size is ngrid * (ngrid -1)
cex Point size
pch Point symbol
col Point colour

Details

Note - only for $m=2$ planar objects

Value

No returned value

Author(s)

Ian Dryden

References

Bookstein, F.L. (1989). Principal warps: thin-plate splines and the decomposition of deformations, IEEE Transactions on Pattern Analysis and Machine Intelligence, 11, 567–585.

Dryden, I.L. and Mardia, K.V. (1998) Statistical Shape Analysis. Wiley, Chichester. Chapter 10.

See Also

procGPA

Examples

data(gorf.dat)
data(gorm.dat)

#TPS grid with shape change exaggerated (2x)
gorf<-procGPA(gorf.dat)
gorm<-procGPA(gorm.dat)
mag<-2
TT<-gorf$mshape
YY<-gorm$mshape
par(mfrow=c(1,2))
YY<-TT+(YY-TT)*mag
tpsgrid(TT,YY,-0.6,-0.6,1.2,2,0.1,22) 
title("TPS grid: Female mean (left) to Male mean (right)")   


[Package shapes version 1.1-1 Index]