Hi, Thanks to Hadley Wickham, I am now able to plot some nice "weather" graphs (see http://www.nabble.com/how-to-plot-image%28%29-without-painting-a-map-%28the-background%29-td15546906.html#a15584405 How to plot a graph on a map ). For some parameters, I would like to increase the number of levels (the number of grey tinges in fact ("nuances" in french - not sure "tinges" is the correct english translation)). I tried to add nlevels=10 to the following command : p <- qplot(data=lonlat1, longitude, latitude, geom="tile", fill=TCDC, xlab="", ylab="") + scale_fill_gradient(low="white", high="grey") + geom_contour(aes(z = TCDC)) + france_map ... but nothings changes. I have always 5 levels for TCDC : 20 / 40 / 60 / 80 /100. http://www.nabble.com/file/p16396028/tcdc_map.jpg Could you please tell me how to solve this easy (except for me) problem ? Have a nice week, Ptit Bleu. -- View this message in context: http://www.nabble.com/ggplots---how-to-increase-the-number-of-levels-tp16396028p16396028.html Sent from the R help mailing list archive at Nabble.com.