Hello. My question here did not lead to a general solution, so I have been experimenting with a voxel approach.
It currently appears to be failing because the “solid difference” component is not successfully cutting the wall geometry from the bounding box.
Please can someone help me to understand why.
Voxelisation.gh (16.9 KB)
Voxelisation.3dm (53.0 KB)
I’m not fully clear on what your goal is, but right now you are trying to do a solid difference using objects of exactly the same size and shape. Your bounding box is set to Per Object, maybe you intended to have a bounding box which contains all of the objects. If this is the case, right click on the bounding box component and select “Union Box”.
I’m also not sure what you’re trying to do.
I think you’re trying to get the empty volume enclosed by your walls.
The GH definition you trying to apply fails to give you proper result because your “walls” are imperfect. See the picture below.
Second thing I don’t get is why do you add objects that overlap?
These:
And in your definition you add them together inside a brep container and feed them to the bounding box. This makes no sense at all.
On top of that above you’re creating a SolidUnion. That was the only thing you need.
I suggest you create your floor and walls such that they enclose inside a box perfectly. then SolidDifference them from their bounding box and you will get an accurate empty volume and continue your definition with the voxelization.
Thanks for your replies Adam & Ivelin
I’m sorry I didn’t make it clear what I was trying to achieve.
I have four walls, a celing and a floor, and I am trying to define the space they surround as a separate volume using Voxelisation.
In terms of the imperfect walls, that was by design, as my workflow will have to deal with inconsistencies in the geometry. In fact, the choice to use Voxels was made to better cater for these inconsistencies.
As to my workflow, I am new to Rhino, and thought that if attempted a solution myself, I would be more likely to get assistance 
That is certain.
