In gnuplot pm3d map plot a 3d data into a surface with color as value of "z". Lets say we have a data file something like this .. 0.00 0.00 0.00 0.00 1.00 0.00 0.00 2.00 0.00 0.00 3.00 1.9358 0.00 4.00 3.618 0.00 5.00 5.17 0.00 6.00 6.93 0.00 7.00 8.82 0.00 8.00 10.692 1.00 0.00 0.00 1.00 1.00 0.00 1.00 2.00 0.00 1.00 3.00 2.1318 .... ... In gnuplot prompt we will do something like this . set pm3d map; set dgrid 20,20 sp "data.dat" u 1:2:3 and this will produce a figure something like a...