converting surf plot of vectors to a Matrix Binary that can be used in GNU plot

I have some MATLAB code that makes a surface plot from different rows of 2-d arrays

surf(C(:,1),C(:,2),d_(:,1),'FaceColor','blue','EdgeColor','none');

I would like to convert this surf plot ouput or the array data into a format that can be used with GNU plot's "splot matrix binary" using the pm3d style.

Does anyone know how to do get an acceptable matrix binary file from my MATLAB surf plot?

Thanks!