Выделение пересечений графиков matplotlib

import pylab
from mpl_toolkits.mplot3d import Axes3D
import numpy
 
 
def Func1 ():
    x = numpy.arange (-3, 3, 0.01) + numpy.random.normal(0,0.4,600)
    y = numpy.arange (-3, 3, 0.01) + numpy.random.normal(0,0.4,600)
       
    xgrid, ygrid = (x, y)
    
    zgrid = 5*numpy.sin(xgrid)*numpy.sin(ygrid) + numpy.random.randint (0, 5, 600)
    
    return xgrid, ygrid, zgrid
 
 
def Func2 ():
    x = numpy.arange (-3, 3, 0.01) + numpy.random.normal(0,0.3,600)
    y = numpy.arange (-3, 3, 0.01) + numpy.random.normal(0,0.3,600)
     
    xgrid, ygrid = (x, y)
    
    zgrid = xgrid**2 + 2*ygrid**2 +numpy.random.randint (0, 5, 600)
     
    return xgrid, ygrid, zgrid
 
 
def Func3 ():
    x = numpy.arange (-3, 3, 0.01) + numpy.random.normal(0,0.2,600)
    y = numpy.arange (-3, 3, 0.01) + numpy.random.normal(0,0.2,600)
            
    xgrid, ygrid = (x, y)
           
    zgrid = 10*numpy.sin(xgrid*ygrid)+numpy.random.randint (0, 5, 600)
 
    return xgrid, ygrid, zgrid
 
x, y, z = Func1()
x1, y1, z1 = Func2()
x2, y2, z2 = Func3()
 
fig = pylab.figure()
axes=Axes3D(fig)
 
axes.plot(x,y,z,'.',  color='yellow')
 
axes.plot(x1,y1,z1,'.', color='black')
 
axes.plot(x2,y2,z2,'.', color='grey')
 
pylab.show()