# Empty graph using implicit_plot3d with contour-option

Hello everybody,

I wanted to make an isosurface plot from a 3d matrix, which contains random values from 0 to 1 at an equally spaced 3d grid.

Therefore I generated random numbers, and reshaped them in a 3d matrix. I interpolated the 3d matrix linearly with the RegularGridInterpolator from scipy. To make a 3D plot of it I am using the implicit_plot3d function of sage with a given contour value.

I get no errors, but in the end the graph is empty, which should not be in my opinion.

Here is my code:

```
from scipy.interpolate import griddata
import numpy as np
from mpl_toolkits.mplot3d import axes3d
import matplotlib.pyplot as plt
from matplotlib import cm
import scipy.interpolate
numbers=np.random.random_sample((1000,)) #generate random numbers
#print numbers
data = np.reshape(numbers, (10, 10, 10)) #reshape the numbers on a 3D matrix
#print data
xi = yi = zi = np.linspace(1, 10, 10)
interp = scipy.interpolate.RegularGridInterpolator((xi,yi,zi), data) #interpolate the 3d matrix with a function
#print xi
var('x,y,z')
#test = implicit_plot3d(interp,(x,1,10),(y,1,10),(z,1,10),contour=0.5)
test = implicit_plot3d(interp==0.5,(x,1,10), (y,1,10),(z,1,10),plot_points=60, color='seagreen')
test.show() #plot the the function at a certain value
#a=(5.,5.,2.)
#interp(a)
```

Any ideas on that?

Thank you very much!