Surface Reconstruction with Lidar

### 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](https://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [x] I have checked the [release documentation](https://www.open3d.org/docs/release/) and the [latest documentation](https://www.open3d.org/docs/latest/) (for `main` branch).

### My Question

Hi i am trying to reconstruct a building with the lidar data set; i cropped out only one building and added a plane of points so now this is a closed point cloud, but my problem is with the vertical walls; i have used RANSAC for proper plane segmentation, what’s next??

Anyfeed back is deeply appreciated.

Thank you