How best to calculate "Negative Space"? Void volumes

[rob2218]

How best to calculate the "voided" areas left from an SEO operation?
See diagram.
My client asked me early on..."Can Archicad calculate the missing space when we do earthwork from the site?"

I said I'd get back to him on that.......so...can we and how?

[matjashka]

Bobby,
How about:

1) Perform SEO Intersection with the volume that cuts the holes in the ground, which will yield the "void" as a result
2) Change the result of intersection into a Morph
3) Query the Morph for Volume using the Element Information dialog box?

I haven't ran the numbers manually, but my resulting Morph looks legit.

[rob2218]

So...I gave it a test.
I converted one of the sites with the SEO voids into the "morph" and the morph yields a "0.00 volume" number? huh? dunno why it does that?

Can anyone explain this?
yet...when the "mesh" stays a "mesh" it will yield a volume number.....see attached image.

[matjashka]

Bobby, see my above exercise, in screenshots.

In SEO, the slab was the Operator and the Mesh was the Target, then I hid the Operator. Turns out, the Element Information correctly returned the Volume of the *result* so you may even skip the Morph. I then converted it to a Morph that shows the same volume as the result of SEO, just to double check.

[edit] my original attachment failed, I think the size of the screenshot was too big.

[rob2218]

I'll have to test out yer method............thank you.

[Bruce]

To my knowledge, ARCHICAD can't do this automatically, like it does with a slab.

The other way (apart from matjashka's method) is to just have an original copy of the site mesh, prior to any editing. Just subtract from its volume the edited mesh's volume.

[Brett Brown]

Just to clarify Bruces reply you seem to want only a certain SEO quantity in red.

Simple, Drag a copy of the mesh to one side gives you a volume without any SEO's. Then drag a copy of the mesh and only the SEO's you want calculated to one side. That will give you another volume. Subtract that from the Non SEO volume of mesh.

[Brett Brown]

Also Rob, Have a look at this Tutorial on how to do your site meshes correctly right from the outset to avoid that unnecessary height. https://www.youtube.com/watch?v=JO2OaigIZbo&t=1353s

[Erwin Edel]

You could also copy the mesh, copy your operators and do an intersect, instead of substraction, you should end up excactly with the negative space.