how to create a 3d polar graph with gnuplot

Question

I'm investigating the frequency responses of microphones.

To help analyse them, I've written a program that will output: arrival angle, frequency(Hz), and response at a given angle and frequency (dB).

I've written a gnuplot script that will graph all this data into a 3d graph:

The code for the gnuplot is:

set xlabel "Arrival Angle (degrees)" font "arial,8"
set ylabel "Frequency (Hz)" font "arial,8"
set zlabel "Gain (dB)" font "arial,8"

set grid lc rgbcolor "#BBBBBB"

set xrange[-180:180]
set yrange[0:20000]
set zrange[-60:0]

unset key
set view 30,56,0.98

splot 'freq.dat' u 1:2:3 with pm3d

I know it's a bit unusual, but what I'd like to do, is represent this on a sort of 3d polar graph, but I can't figure out how to do it. The (bad) drawing below, shows the sort of thing I've been trying to achieve:

Can anybody point me in the right direction?

Thanks in advance. Dave.

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Update 26-April-2013

I've been playing around and have created an updated script:

reset
set title "3D version using cylindrical coordinate system"
set ticslevel 0.0
set view 30,56,0.98
set angles degrees
set mapping cylindrical
set parametric
set zrange[-60:0]
unset key
splot 'freqResp.dat' u 1:3:2 with pm3d

This script almost does what I need, however unfortunately it only renders the back half of the graph. The front half remains unplotted. For example:

Incase anybody fancies playing around with the script above, I've put the 'freqResp.dat' file is here.

When I plot the same file with my original script, I get the image below (so all the data is present in the freqResp.dat file):

Can anybody help me with getting gnuplot to render the front half of the graph? Thanks Dave.

Answer 1

After help from several users, the final answer is:

reset
set title "3D version using cylindrical coordinate system"
set ticslevel 0.0
set view 30,56,0.98
set angles degrees
set mapping cylindrical
set parametric
set zrange[-60:0]
unset key
set pm3d depthorder 
splot 'freqResp.dat' u 1:3:2 with pm3d

Thanks to all who helped