title: smoothing outer edges in matplotlib
body: <p>have two questions maybe someone can help me.
  I want to plot a stereographic projection with contoruf and want to  color the higher parts in the Z direction in Matplotlib.
  For that i have two questions.</p>
  
  <ol>
  <li><p>I’m plotting with contourf before im using meshgrid and griddata, the the other edges are not smooth how can i smooth them?
  <img src="https://i.stack.imgur.com/fGRDR.png" alt="enter image description here">i </p></li>
  <li><p>I want to have a log scale in Z how can i do that, i tried to use ticker.LogLocator but then i got just some parts colored.  </p></li>
  </ol>
  
  <p>Here my code:</p>
  
  <pre><code># craation of a 2D grid
  xi = np.linspace(min(X), max(X))
  yi = np.linspace(min(Y), max(Y))
  
  X1, Y1 = np.meshgrid(xi, yi)
  
  ##### interpolation
  Z1 = griddata(X, Y, Z,xi,yi)
  
  plt.contourf(X1,Y1,Z1,50,cmap=plt.cm.rainbow,vmax=abs(Z1).max(),
               locator=ticker.LogLocator)
  
  plt.colorbar()
  
  plt.xlim(-1,1)
  plt.ylim(-1,1)
  
  plt.show()
  plt.set_zscale('log')
  plt.set_xlabel('X')
  plt.set_ylabel('Y')
  
  plt.show()
  </code></pre>