Yes, vertex-based HD would be a nice addition.

Custom percent could be added to labelmap too. There is already a function for this:

```
/*! \brief Set the fraction of voxels to include when computing
the percent hausdorff distance. The input value should be
a number between 0 and 1. The default value is 0.95. */
void set_hausdorff_distance_fraction (
float hausdorff_distance_fraction);
```

I did add some code for minimum as well. (But not yet tested.)

```
/*! \brief Return the minimum Hausdorff distance */
float get_min_min_hausdorff ();
/*! \brief Return the minimum boundary Hausdorff distance */
float get_min_min_boundary_hausdorff ();
```

The boundary value differs from the set value when one segment is completely contained within the other, where the set distance is zero but the boundary distance is non-zero.