[R-sig-Geo] overlay contour lines with labels over spplot with color regions?

[Martin Ivanov]

Dear R users,

I have the following problem. I plot a SpatialPixelsDataFrame object 
with spplot and I need to add a contourplot
of another spatial variable. To be more precise, I plot the 
SpatialPixelsDataFrame of the mean precipitation over Germany with 
coloured regions and I want to overlay the isolines of the 500, 1000 and 
1500 m height above sea level. Of course I can plot the lines as 
SpatialLines using the sp.layout argument to spplot, but so I lose the 
labels on the lines. And I want the height above sea level to be 
labelled just as it is labelled in a contour plot. Is it possible to 
achieve that with lattice?

I am still new to lattice, so I beg Your excuse in case I am asking 
something trivial. I googled a lot and tried a lot of things, but none 
worked. I tried with contour, it does work with Spatial objects, but 
unfortunately contour does not seem work with lattice. And the lattice 
equivalent contourplot does not recognise Spatial objects.

I am already out of ideas. I am looking forward to Your replies. Any 
suggestions will be appreciated.

Best regards,

Martin

-- 
Dr. Martin Ivanov
Eberhard-Karls-Universität Tübingen
Mathematisch-Naturwissenschaftliche Fakultät
Fachbereich Geowissenschaften
Water & Earth System Science (WESS)
Keplerstraße 17, 72074 Tübingen, Deutschland
Tel. +4970712975023