topic Re: How best to calculate "Negative Space"? Void v in Modeling

How best to calculate "Negative Space"? Void volumes

rob2218 — Wed, 24 May 2023 17:57:03 GMT

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?

Re: How best to calculate "Negative Space"? Void v

matjashka — Fri, 02 Jun 2017 18:47:03 GMT

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.

Re: How best to calculate "Negative Space"? Void v

rob2218 — Fri, 02 Jun 2017 19:24:39 GMT

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.

Re: How best to calculate "Negative Space"? Void v

matjashka — Fri, 02 Jun 2017 20:03:20 GMT

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.

Re: How best to calculate "Negative Space"? Void v

rob2218 — Fri, 02 Jun 2017 20:15:15 GMT

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

Re: How best to calculate "Negative Space"? Void v

Bruce — Sat, 03 Jun 2017 05:29:53 GMT

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.

Re: How best to calculate "Negative Space"? Void v

Brett Brown — Sat, 03 Jun 2017 10:43:57 GMT

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.

Re: How best to calculate "Negative Space"? Void v

Brett Brown — Sat, 03 Jun 2017 10:50:23 GMT

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

Re: How best to calculate "Negative Space"? Void v

Erwin Edel — Tue, 06 Jun 2017 09:01:47 GMT

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.