title: Open3d Python, Type error using TriangleMesh.create_from_point_cloud_alpha_shape()
body: <p>I am trying to use open3d to create an "alphahull" around a set of 3d points using <code>TriangleMesh</code>. However I get a TypeError.</p>
  
  <pre><code>import open3d as o3d
  import numpy as np 
  
  xx =np.asarray([[10,21,18], [31,20,25], [36,20,24], [33,19,24], [22,25,13], [25,19,24], [22,26,10],[29,19,24]])
  
  cloud = o3d.geometry.PointCloud()
  cloud.points = o3d.utility.Vector3dVector(xx)
  mesh = o3d.geometry.TriangleMesh.create_from_point_cloud_alpha_shape(pcd=cloud, alpha=10.0)
  </code></pre>
  
  <p>output:</p>
  
  <pre><code>    Traceback (most recent call last):
  File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  TypeError: create_from_point_cloud_alpha_shape(): incompatible function arguments. The following argument types are supported:
  1. (pcd: open3d.open3d.geometry.PointCloud, alpha: float, tetra_mesh: open3d::geometry::TetraMesh, pt_map: List[int]) -&gt; open3d.open3d.geometry.TriangleMesh
  </code></pre>
  
  <p>The error says the object I am passing the function is the wrong type. But when I check the type I get this:</p>
  
  <pre><code>&gt;&gt;print(type(cloud))
  &lt;class 'open3d.open3d.geometry.PointCloud'&gt;
  </code></pre>
  
  <p>Please can someone help me with this error?</p>
  
  <p><strong>Note</strong>: A comment on this post <a href="https://stackoverflow.com/questions/58174767/python-open3d-no-attribute-create-coordinate-frame">Python open3D no attribute &#39;create_coordinate_frame&#39;</a> suggested it might be a problem with the installation and that a solution was to compile the library from source. So I compiled the library from source. After this ran 
      <code>make install-pip-package</code>. Though I am not sure it completed correctly because I couldn't <code>import open3d</code> in python yet; see output of installation: <a href="https://pastebin.com/sS2TZfTL" rel="nofollow noreferrer">https://pastebin.com/sS2TZfTL</a> 
  (I wasn't sure if that command was supposed to complete the installation, or if you were still required to run pip? After I ran <code>python3 -m pip install Open3d</code> I could import the library in python.)</p>