Volume Calculation fails - grouping

jemagnussen

Hi all,

I would really appreciate some assistance on this one, for some reason I can't make a solid group when grouping this model.
All the other models I have made in the same project are grouped as solids and thereby giving me the volume automatically.

I am fully aware that I have done a mistake somewhere, but can't see where the problem is.

Best regards
Jesper

PS: I also placed the model in Google 3D Warehouse: Jetty Head (Filter Layer)

FilterLayerHead.skp

Gaieus

Using ThomThom's Solid inspector plugin reveals a fault (that circle is drawn by the plugin). Zooming closer shows there is a small, stray line there (it was not grouped BTW but I guess that's due to you extracting it).

Deleting that line makes it solid.

TIG

If you group all of your geometry and then get entity-info on it then it reports as a group [that is, it's not solid].
If you edit that group and select-all you get 300 entities listed in entity-info.
If you run thomthom's Cleanup tool to remove unfaced 'lonely' edges [or another stray-edge removal script - I tried two] then the entity-info count will fall to 299 - one edge is removed
If you exit the edit session and then select the group it will then show as a 'solid' group in entity-info.

To be a solid the object's edges must have two faces - no more and no fewer.
More that two faces per edge occur with internal 'partition' faces which result in an edge with three or more faces, or when volumes touch exactly on an edge so that that edge then has four faces.
A 'flap' will have an edge with only that one face so there's no solid-volume either.
In your case it seems you have somehow got an edge with no face at all - it's very tiny - I couldn't initially find it [bottom right-side - see Gai's image...]!
This can occur with solid operations when faces/edges get very small [<~1mm] - but I see your object is meters big...

So the lesson is 'clean' your geometry if it's vital to you that it's 'solid'

EDIT: Gaieus beat me to it - since I already typed it I'll leave it

jemagnussen

Thanks guys,

That was a very usefull hint to use the "Solid Inspector Plugin" that will be part of my toolbox from now on...
Yes, I had exploded it before uploading.
Thank you for the explanation TIG, nice when someone takes the time to explain things in detail, then there is abetter chance that it will stick to the memory sticks in my old brain.

Best regards
Jesper

Gaieus

@tig said:

To be a solid the object's edges must have two faces - no more and no fewer.

Very "solid" definition, thanks! I have never thought of this approach (only the "long list" way what a solid has to and must not consist of)