Python interface about open3d

[qianyizh]

Actually what's in Open3D now is the right python semantic. By default python = assigns reference. You can check, np array has exactly the same behavior as Open3D data structures.

If you want copy, you should explicitly use copy or deepcopy. Both have been defined in Open3D (by a convenient macro).

[syncle]

Thanks for pointing out the right reference. The following code works as expected.

import copy
pcd_1_trans = copy.copy(pcd_1)
pcd_1_trans.Transform(trans)

Originally, I tried with

pcd_1_trans = pcd_1
pcd_1_trans.Transform(trans)

this transforms pcd_1 too because pcd_1_trans is reference of pcd_1.