I am not really sure what you mean by showing the effects for different groups, but you can set the limits of the coloured contours by using zlim:

e.g. visreg2d(fit,x="Wind",y="Temp",plot.type="image",zlim=c(-100,100))

Or using the command levels to set the levels more explicitly:

visreg2d(fit,x="Wind",y="Temp",plot.type="image",levels=seq(-100,160,20))

As far as I know it is just a normal image.plot, so you use the same commands as you would using in making an image.plot.

Hey Chris,

Thanks for your quick response! It is very logical but I couldn't find it anywhere and my own tries (zscale etc) did not work out.

Tim

I suppose the split of the z-scale ii is not possible in visreg2d. Albeit I like visreg, I suggest alternative forms of depict the question by means of ggplot2. This package has higher plasticity and possibly meet your expectations.