Parameters tuning in Open3D

For convenience, I used the FastGlobalRegistrtion implementation in the Open3D library and used the sample code from this page:
http://www.open3d.org/docs/release/tutorial/Advanced/global_registration.html#id2

But I found that the parameters in Open3D is different with this repo. As I know, there is only a voxel_size para in Open3D's implemention. When I tune voxel_size , I can only get some not very good results like this:

So I wonder if there is a instruction of how to tune paras of Open3D's implemention.

[cherwinsd]

Hello, I have also encountered this problem. How did you solve it