\definecolor{Tan}{cmyk}{0.14,0.42,0.56,0}
\psset{lightsrc=30 90 30,unit=0.75}
\begin{pspicture}(-6,-6)(6,6)
\psset{viewpoint=100 70 15 rtp2xyz,Decran=100}
\psSolid[object=grille,base=-7 7 -4 4,action=draw*,linecolor=red](0,0,-4)
\psSolid[object=new,
   incolor=yellow!50,hue=0 0.7 0.5 1,hollow,linewidth=0.5\pslinewidth,
   sommets= (sommets_unionspheres.dat) run,
   faces={(faces_unionspheres.dat) run}]%
\gridIIID[Zmin=-4,Zmax=4](-7,7)(-4,4)
\end{pspicture}