Jing Zhao

mesh smoothing creates nan

2

### Checklist - [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues). - [x] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip). - [X] I have checked the [release...

Hi! Thank you for this awesome repository. I have some textured models obtained using photogrammetry software. I plan to use xatlas to repack the texture atlas. However, I found xatlas...

`_sigma` is not released in [destructor](https://github.com/pitzer/SiftGPU/blob/master/src/SiftGPU/SiftGPU.cpp#L129). https://github.com/pitzer/SiftGPU/blob/master/src/SiftGPU/SiftGPU.cpp#L464