Creating a trellised (faceted) thin-plate spline response surface

Question

I am trying to plot a bunch of thin-plate spline response surfaces for measurements related to two continuous variables plus one discrete variable. So far, I have been subsetting the data based on the discrete variable to generate pairs of plots, but it seems to me there should be a way to create some slick trellised plots instead. It seems like this could be done by faceting heatmaps in ggplot2 with geom_tile and geom_contour , but I am stuck on

(1) how to reorganize the data (or interpret the predicted surface data) for plotting with ggplot2 ?

(2) syntax for creating trellised heatmaps with base graphics? or

(3) ways to use graphics from rsm to accomplish this ( rsm can cope with higher-order surfaces, so I could coerce things to some extent, but plots aren't fully trellised).

Here's an example of what I've been working with so far:

library(fields)
library(ggplot2)

sumframe<-structure(list(Morph = c("LW", "LW", "LW", "LW", "LW", "LW", 
"LW", "LW", "LW", "LW", "LW", "LW", "LW", "SW", "SW", "SW", "SW", 
"SW", "SW", "SW", "SW", "SW", "SW", "SW", "SW", "SW"), xvalue = c(4, 
8, 9, 9.75, 13, 14, 16.25, 17.25, 18, 23, 27, 28, 28.75, 4, 8, 
9, 9.75, 13, 14, 16.25, 17.25, 18, 23, 27, 28, 28.75), yvalue = c(17, 
34, 12, 21.75, 29, 7, 36.25, 14.25, 24, 19, 36, 14, 23.75, 17, 
34, 12, 21.75, 29, 7, 36.25, 14.25, 24, 19, 36, 14, 23.75), zvalue = c(126.852666666667, 
182.843333333333, 147.883333333333, 214.686666666667, 234.511333333333, 
198.345333333333, 280.9275, 246.425, 245.165, 247.611764705882, 
266.068, 276.744, 283.325, 167.889, 229.044, 218.447777777778, 
207.393, 278.278, 203.167, 250.495, 329.54, 282.463, 299.825, 
286.942, 372.103, 307.068)), .Names = c("Morph", "xvalue", "yvalue", 
"zvalue"), row.names = c(NA, -26L), class = "data.frame")

sumframeLW<-subset(sumframe, Morph=="LW")
sumframeSW<-subset(sumframe, Morph="SW")

split.screen(c(1,2))
screen(n=1)
surf.teLW<-Tps(cbind(sumframeLW$xvalue, sumframeLW$yvalue), sumframeLW$zvalue, lambda=0.01)
summary(surf.teLW)
surf.te.outLW<-predict.surface(surf.teLW)
image(surf.te.outLW, col=tim.colors(128), xlim=c(0,38), ylim=c(0,38), zlim=c(100,400), lwd=5, las=1, font.lab=2, cex.lab=1.3, mgp=c(2.7,0.5,0), font.axis=1, lab=c(5,5,6), xlab=expression("X value"), ylab=expression("Y value"),main="LW plot")
contour(surf.te.outLW, lwd=2, labcex=1, add=T)
points(sumframeLW$xvalue, sumframeLW$yvalue, pch=21)
abline(a=0, b=1, lty=1, lwd=1.5)
abline(a=0, b=1.35, lty=2)

screen(n=2)
surf.teSW<-Tps(cbind(sumframeSW$xvalue, sumframeSW$yvalue), sumframeSW$zvalue, lambda=0.01)
summary(surf.teSW)
surf.te.outSW<-predict.surface(surf.teSW)
image(surf.te.outSW, col=tim.colors(128), xlim=c(0,38), ylim=c(0,38), zlim=c(100,400), lwd=5, las=1, font.lab=2, cex.lab=1.3, mgp=c(2.7,0.5,0), font.axis=1, lab=c(5,5,6), xlab=expression("X value"), ylab=expression("Y value"),main="SW plot")
contour(surf.te.outSW, lwd=2, labcex=1, add=T)
points(sumframeSW$xvalue, sumframeSW$yvalue, pch=21)
abline(a=0, b=1, lty=1, lwd=1.5)
abline(a=0, b=1.35, lty=2)

close.screen(all.screens=TRUE)

Answer 1

As noted in a comment, melt() can be used to reshape the Tps() output, then it can be reformatted a bit (to remove NA's), recombined into a single data frame, and plotted. Here are plots with ggplot2 and levelplot :

library(reshape)
library(lattice)

LWsurfm<-melt(surf.te.outLW)
LWsurfm<-rename(LWsurfm, c("value"="z", "Var1"="x", "Var2"="y"))
LWsurfms<-na.omit(LWsurfm)
SWsurfms[,"Morph"]<-c("SW")

SWsurfm<-melt(surf.te.outSW)
SWsurfm<-rename(SWsurfm, c("value"="z", "X1"="x", "X2"="y"))
SWsurfms<-na.omit(SWsurfm)
LWsurfms[,"Morph"]<-c("LW")

LWSWsurf<-rbind(LWsurfms, SWsurfms)

LWSWp<-ggplot(LWSWsurf, aes(x,y,z=z))+facet_wrap(~Morph)
LWSWp<-LWSWp+geom_tile(aes(fill=z))+stat_contour()
LWSWp

or: levelplot(z~x*y|Morph, data=LWSWsurf, contour=TRUE)

Answer 2

require(rgl)
open3d()
plot3d
surface3d(surf.te.outSW$x, surf.te.outSW$y, surf.te.outSW$z, col="red")
surface3d(surf.te.outLW$x, surf.te.outLW$y, surf.te.outLW$z, col="blue")
decorate3d()
      rgl.snapshot("OutRGL.png")

Another version where I scaled the x and y values by a factor of 10 and rotated to "look through" the gap. If this were your choice you might want to look at ?scaleMatrix