question regarding visib_gt_min

```
    # Minimum visible surface fraction of a valid GT pose.
    "visib_gt_min": 0.1,

```

in `vi lib/pysixd/scripts/show_performance_bop19.py`

isn't this threshold so low? is there any explorative work to back this up? I think 0.4-0.6 would make sense but 0.1 might be too low of a threshold to rely on for training/test.



