Plotting multiple heat maps gnuplot

Question

I have been attempting to plot two heat maps with data from two data files using gnuplot. I have plotted heat maps using gnuplot before, but never tried to "overlay them".

My attempt is as follows:

    set terminal pngcairo
    set xrange[-2:2]
    set yrange[-2:2]
    unset surface
    set view map
    set pm3d       
    set size square
    set key outside
    set pm3d depthorder 
    splot "file_1" u 1:2:3 w pm3d notitle, \
    "file_2" u 1:2:3 w pm3d notitle   

This produces the following output:

There is a faint ring which corresponds to one of the data files but this is not what is desired. By removing the map you can see what the data looks like:

So the first plot has plotted the outer, lower ring but seems to have not plotted the inner taller ring even though it has registered its scale. What I am looking for is a view of this second plot from above.

By manipulating the view of this 3-D plot, I can do this:

but is there a way to obtain a top down view of this plot without having to set the view, and by just using the view map and splot commands? The view method does not look as good, and I would like to know why it does not behave as expected.

Thank you in advance

Answer 1

In the meantime that the bug will be fixed you can use the following workaround:

max(a,b)=(a>b)?a:b
splot "<paste file_1 file_2" u 1:2:(max($3,$6)) w pm3d notitle

Because in this case depth ordering is equivalent to sorting the z values.