Hi,

is there a way to precisely calculate the porosity in a box with periodic boundaries? I tried the commands

`woo._utils2.porosity(S.dem,None,box=S.cell)`

but it wouldn't take my input cell. In your examples you use an AlignedBox3 for the calculation.

Another question is how you compute the porosity in the box -- do you consider the overlap at the contacts?

Right now, I am calculating the porosity with, which does not consider the overlap:

```
vs=sum([p.shape.volume for p in S.dem.par])
v=S.cell.volume
porosity = (v-vs)/v
```

Yes, that's what I thought.

I'll try to do it for spheres, after I am back in Dresden in 2 weeks. I am in Sydney working with Itai right now ;)