[R] smoothing bathymetry

[Jens]

Dear R Users, 

Using the following R-script I created the first image 

> require(akima) 
> require(spatial) 
> dep <- interp(long, lat, depth, xo=seq(1,990,10), yo=seq(1,990,10), 
+ extrap=FALSE, ncp=0,duplicate = "mean", dupfun = NULL) 

http://r.789695.n4.nabble.com/file/n3431391/Rpics.bmp 

Where "long" are x-coordinates between 1 and 1000, "lat" are y-cordinates
between 1 and 1000, and depth are depth values corresponding to the x and y
coordinates. All data are in vector form. 

I would like to extrapolate the data points beyond the data set, by setting
extrap=TRUE, filling out the entire 1000x1000 grid. 
I attempted this using the following script, which generated the second
image. 

>dep <- interp(long, lat, depth, xo=seq(1,990,10), yo=seq(1,990,10), 
+ linear=FALSE,extrap=TRUE, ncp=NULL,duplicate = "mean", dupfun = NULL) 

However, as seen in the image, this results in a messy looking bathymetry,
with erros. Any suggestions on what went wrong or other packages or
functions I could try to would be greatly appreciated? 

I played around with the krig.image function in the "fields" package, but
didnt have much luck.

Sincerly 
Jens 


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