[R] Surfaceplot3D with wireframe

[Deepayan Sarkar]

On 10/10/06, Gustaf Granath <gustaf.granath at ebc.uu.se> wrote:
> Hi,
> I want to make a surface3D plot of a landscape. I have cordinates (x, y, z)
> recorded with a GPS. The datapoints are not evenly distributed within the
> rectangular area.
>
> To do a fast 3D plot I used following.
>
> > library(grid)
> > library(lattice)
> > v <- read.table("clipboard")
> > names(v) <- c("x", "y", "z")
> > wireframe(z ~ x * y, data = v)
>
> However I just get an empty box with no 3D grid. I have tried with other data
> and then it usually works. But I cant get it to work with my data.
> Here is a sample of my data (x, y, z). I think there is something in my data set
> that wireframe doesnt like.

Yes, and you have already stated what that is, namely that "The
datapoints are not evenly distributed within the rectangular area". As
it says in the first multiple-sentence paragraph in help page for
wireframe:

          ... In the case of 'wireframe',
          calculations are based on the assumption that the 'x' and 'y'
          values are evaluated on a rectangular grid defined by their
          unique values.  The grid points need not be equally spaced.

You need to use your favorite smoothing method to evaluate z values on
a grid. ?levelplot has an example using loess (the akima package is
also popular, although I'm not personally familiar with it).

Another alternative is using some form of triangulation (e.g. voronoi
tesselation). This should be possible, but is not trivial.

-Deepayan

> Any ideas?? Are there better commands to use?
> (I have tried to change the magnitude of the numbers but that doesnt help)
>      y               x            z
> 6659592.078     1585162.959     59.229
> 6659591.348     1585164.402     59.159
> 6659590.494     1585163.294     59.205
> 6659589.466     1585158.968     59.290
> 6659589.229     1585159.390     59.246
> 6659588.963     1585158.895     59.201
> 6659589.475     1585158.617     59.199
> 6659589.808     1585159.206     59.135
> 6659592.361     1585161.707     59.447
> 6659592.387     1585161.319     59.437
> 6659592.590     1585161.871     59.217
> 6659591.989     1585162.156     59.163
> 6659591.934     1585161.489     59.358
> 6659590.340     1585158.060     59.352
> 6659590.228     1585157.714     59.138
> 6659590.957     1585157.947     59.145
> 6659590.422     1585158.344     59.214
> 6659589.904     1585158.024     59.175
> 6659589.877     1585162.033     59.346
> 6659589.967     1585161.674     59.197
> 6659590.109     1585162.062     59.205
> 6659589.778     1585162.572     59.152
> 6659589.591     1585161.876     59.187
> 6659591.783     1585156.210     59.561
> 6659592.164     1585156.764     59.266
> 6659590.352     1585156.154     59.339
> 6659590.890     1585154.720     59.278
> 6659592.520     1585155.023     59.250
> 6659593.127     1585166.690     59.217
>
> Regards,
> Gustaf