Intersections in Notional but not Actual Buidling

[JohnLloyd]

I'm having problems with a large and fairly geometrically complicated model where the Actual Building is reported as having no intersections, but the Notional has a lot of intersecting zones.

If I export the Actual building geometry as a GEM and then re-import it, I get a lot of intersection errors.

This is leading me to believe that the Actual building does in fact have a lot of intersections, but for whatever reason the Model Check feature is not picking them up. Has anyone experienced anything like this before?

I don't really want to re-import the geometry and then fix all intersections because I will then need to reassign all of the constructions; it took me full days to assign everything correctly last time as the size of the model makes selecting different surfaces a very slow task. Any ideas or suggestions?

[RossThompson87]

Have you accidentally turned intersections off?

Holding down the escape key and right clicking in the applications pane lets you do this (i.e. where you select which module to work in).

Other than that I have no idea.

Ross

[JohnLloyd]

No, intersections are on.

And even if they weren't, I still think the Model Check option would flag up a list of intersections.

[ZapBran]

Hi John

I've not seen this (cause you can't play with the notional building in Modelit... or I don't think you can at least) but I think I've experienced it when I get a shading file problem with the notional and not the actual. In fact I just put my oar in about that in another post a moment ago.
I think it's a problem at a ridiculous low level (sub mm) that doesn't show up when you look at the vertices cause you only see to 6 dp or so but it's not really that number because inside the data structure it is actually storing it to a jillion decimal places and then rounding differently when it does different things. So when the geometry is not getting played with (say in actual building) the model seems fine but then when it creates the notional building it has a spaz attack because it does different things when writing the file for suncast (cause it needs to write out a file I would assume to set decimal places) than it does for check it.
Would be interesting to hear from a programmer to see if I'm right (or just half drunk).

Zap.

[JohnLloyd]

Quick tip for you Zap, type "dumpnm" into the key-in command box and it will export the Notional geometry as a Gem file so you can then import it into ModelIT and have a good snoop around. That's how I found all these intersection problems.

[Complex Potential]

Hey John

You seem to have quite a few of these handy commands, any chance of you posting a thread listing them all?

[JohnLloyd]

No chance, they're strictly on a need to know basis.

I'm just entering my 8th year (or is it 9th?) of using IES full time. I guess you pick up a few things as you go!

Seriously though, you'll find a lot of them in this document: http://www.iesve.com/downloads/help/Mod ... KeyIns.pdf

[Complex Potential]

Very handy, many thanks.

It's always good to keep a few secrets of course

[ZapBran]

John... you are a wizard of some kind!
Thanks for that.
Zap.

[JohnLloyd]

I've since discovered that sometimes the export / import process can cause intersections because it uses a reduced degree of accuracy on the vertex positions. This leads to rounding errors which cause intersections.

With that in mind, perhaps the problem is not related to intersections in the Notional but something less obvious.

I *HATE* working on large models. They're very slow and cumbersome to work on and they always seems to have so many more geometry problems than smaller ones.

In four days I've made very little progress with this project; it's so demoralising!