imshow in 3d plot

In the plot below, taken from matplotlib's gallery, contourf is used to create a 2d plot beneath the 3d one. My question is, is it possible to use imshow to do the same thing? I would like the colors in the 2d plot to be smoother.

Making the 2d plot seems to be possible because contourf accepts a zdir argument, while I've looked and imshow doesn't. That suggests that it isn't possible, but why not? pcolor would also get the job done, is it possible with that?

Just specify the levels= option for the contourf, e.g.

from mpl_toolkits.mplot3d import axes3d
import matplotlib.pyplot as plt,numpy as np
plt.clf()
fig = plt.figure(1)
ax = fig.add_subplot(projection='3d')
X, Y, Z = axes3d.get_test_data(0.05)
ax.plot_surface(X, Y, Z, rstride=8, cstride=8, alpha=0.3)
cset = ax.contourf(X, Y, Z, zdir='z', offset=-100,
        levels=np.linspace(-100,100,1200),cmap=plt.cm.jet)
cset = ax.contourf(X, Y, Z, zdir='x', offset=-40, cmap=plt.cm.jet)
cset = ax.contourf(X, Y, Z, zdir='y', offset=40, cmap=plt.cm.jet)
ax.set_xlabel('X')
ax.set_xlim(-40, 40)
ax.set_ylabel('Y')
ax.set_ylim(-40, 40)
ax.set_zlabel('Z')
ax.set_zlim(-100, 100)    
plt.show()