title: Python open3D no attribute 'create_coordinate_frame'
body: <p>I want to show the coordinates while visualizing a point cloud in open3D with Python. According to the <a href="http://www.open3d.org/docs/release/tutorial/Basic/visualization.html" rel="nofollow noreferrer">documentation</a>, I wrote the following code, in which the third line is supposed to create a coordinate. (Suppose <code>point_cache</code> is a <code>np.array</code> with shape <code>(442368, 3)</code>)</p>
  
  <pre><code>pcd = o3d.geometry.PointCloud()
  pcd.points = o3d.utility.Vector3dVector(point_cache)
  mesh_frame = o3d.geometry.TriangleMesh.create_coordinate_frame(size=0.6, origin=[-2, -2, -2])
  o3d.visualization.draw_geometries([pcd, mesh_frame])
  </code></pre>
  
  <p>But it showed the following error, suggesting there is no an attribute called <code>create_coordinate_frame</code> in <code>TriangleMesh</code>.</p>
  
  <pre><code>---------------------------------------------------------------------------
  AttributeError                            Traceback (most recent call last)
  &lt;ipython-input-20-2e528bfc7404&gt; in &lt;module&gt;
        1 pcd = o3d.geometry.PointCloud()
        2 pcd.points = o3d.utility.Vector3dVector(point_cache)
  ----&gt; 3 mesh_frame = o3d.geometry.TriangleMesh.create_coordinate_frame(size=0.6, origin=[-2, -2, -2])
        4 o3d.visualization.draw_geometries([pcd, mesh_frame])
  
  AttributeError: type object 'open3d.open3d.geometry.TriangleMesh' has no attribute 'create_coordinate_frame'
  </code></pre>
  
  <p>I wonder why this error occurs since the third line is identically the same as the documentation.</p>
  
  <p>My version of open3D is as follows.</p>
  
  <pre><code>[Frost@CC’s Mac ~]$ python3 -m pip show open3d
  Name: open3d
  Version: 0.8.0.0
  Summary: ['Open3D is an open-source library that supports rapid development of software that deals with 3D data.']
  Home-page: http://www.open3d.org
  Author: Open3D Team
  Author-email: info@open3d.org
  License: MIT
  Location: /Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages
  Requires: notebook, widgetsnbextension, ipywidgets, numpy
  Required-by:
  </code></pre>