[rrd-users] unusual chart type ?

[Thomas Kurz]

Hi,

I am wondering how much effort it would be to display a time series with 
two variables in the following way:

* horizontal axis = days    (e.g. 03/01/2009  ... 03/31/2009) as 
vertical bars over the whole height
* vertical axis     = time of day  ( 00:00  ... 23:59)
* the values of one variable would be color palette coded
* the values of a second variable would be overlayed as contour plot

I've realized this kind of graph using "R" before.

I use it e.g. to show how the day-by-day-trend of  a photovoltaic 
inverter's mode switching timepoints
are related to the daily sunshine intensity.

Is there a name for such a plot?
Anyone done that before?
Anyone has an idea how to do it?

I've not yet done much with rrdtool, but if you consider it right to do 
this, I would spend the necessary time.

Many thanks in advance,
    Thomas