Key becomes invisible in pm3d gnuplot

Question

I am using following code to draw a graph in gnuplot using pm3d map:

set pm3d map
set pm3d corners2color c1
spl \'patternD0pt02.dat\' title \"(a)\"

Answer 1

Indeed, the title is hidden behind the surface and there is no option set key front. This is a bug in 4.6. and is fixed in 5.0.

You can workaround by placing a normal label, since the title of a pm3d plot doesn't plot a sample item. Putting a white rectangle behind the lable is a bit tricky:

set label center at graph 0.95,0.95 front '(a)'
set object rectangle front at graph 0.95,0.95 size char 5,2 fc rgb 'white' fillstyle solid noborder

A full, working example is:

set terminal pngcairo size 800,600
set output 'foobar.png'

set xrange [0:10]
set yrange [0:10]
set samples 20
set isosamples 20

set pm3d map

set label center at graph 0.95,0.95 front '(a)'
set object rectangle front at graph 0.95,0.95 size char 5,2 fc rgb 'white' fillstyle solid noborder
splot '++' using 1:2:1

The result with 4.6.4 is: