Great discussion here; very heartening to know that there are several of us wrestling with these issues.
In our office we’ve got a semi-formalized approach : $-explication structure de fichier BIM dans sketchup-edit-05-12-2023.pdf (3,5 Mo)
It’s in french (if I get an hour or so I’ll translate to English) which explains how we try and structure our files - obviously it’s an ongoing open-ended process & we’re learning all the time.
The main thing is that the engineers & contractors with whom we operate seem to be able to exploit our ifc files (always generated vie the IFC-manager plugin).
For the time being we only use the 2x3 schema as it still seems to be what our industry uses here in France - this is a shame as there’s obviously more granularity in the more recent IFC schemas (4 & 4.3)
Not in our document, on the question of colour/texture, it would appear that only color/texture applied at the group/component level reliably transfers on export.
Notes on the different IFC schema versions are here - IFC Schema Specifications - buildingSMART Technical
Hope that helps
I’ve been trying to experiment on classifications and get the following results:
I can’t get a layered object to export as IfcWall or IfcRoof or IfcSlab.
I can’t get IfcBuildingElementPart to become part of a hierarchy like IfcWall > IfcBuildingElementPart
I get all sorts of changes in hierarchy and added DC names like DC_Dachy, DC_Sciany, DC_Okna, DC_Building_Element_Proxy (I’m sure these are Duch auto DC names, but I can’t find them in the sketchup model under DC properties)
I can export the model and it shows in a BIM viewer like BIMvision, but I can’t get it to consistently replicate Sketchup’s hierarchy.
I’ve also tried exporting using the Sketchup’s exporter but keep seeing the same kind of stuff.
I’m attaching the Sketchup file here as well as the resulting IFC exports:
That’s strange, you’re also using BIM vision, but my buttons and menus are not installed correctly. Their names aren’t right. There is some kind of error in the model tree too, where you have logical element names whilst I have the DC names. It looks some sort of language issue. where the names of elements are missing…
What kind of classification do you guys add to Context, Neighbouring Buildings, and all sort of elements outside the actual site?
It seems that, if I add a site model outside of the site, IFC Manager adds a new site, and converts the terranin and buildings into storeys. I can live with that if that’s the only way, but I’d much rather have that stuff outside of my project.
Also, for terrain, I find that it’s easier to have a solid group on the bottom of my building, for modelling purposes. I’m adding that to the building itself as an IfcGeographicElement, but I guess that isn’t standard practice. It does seem to work, but looks untidy in BIM vision.
What’s cool about my method is that I can use Double Cut, by @Whaat to dig the ground itself, like this (even if it fails sometimes):
Hi, as per - https://forums.sketchup.com/uploads/short-url/5zXzDIeRwKNVExSuO4SijfvQLOD.pdf It’s important to have the terrain object inside the “Site” component and why not indeed use the IfcGeographicElement classification, seems logical to me.
If you leave it outside the Site (ifcSite) component, indeed ifcManager will create a default one, which will make a rather confused file for anyone you send it to.
The thing that confuses me is if the neighbouring houses and plots should be inside my site, which I think should not.
So, for neighbouring buildings and roads or other Geographic Elements, will I have several sites? Each featuring one or more buildings and their terrains?
I think we have to consider that “site” means chunk of the earth’s crust, however big or small that is. And all buildings, including neighbours, and our projects, are on that crust… We just classify & name the neighbouring buildings as “B-Bat-xxx” and put them on a Tag (layer) that we can turn off if they get in the way.
Tag for the existing condition of the project site.
Tag for buildings. Their visibility is managed by the site’s visibility, but I might find the need to have tags for buildings outside of the site.
So, under the project I have several sites and on each site, one or more buildings and terrains. Sometimes, for sites that are from project, I only have a single solid that merges buildings and terrain.
The structure is, therefore:
IfcProject
IfcSite (Main Site and )
IfcBuilding
IfcGeographicElement
IfcSite (Neighbouring Sites)
IfcBuilding
IfcGeographicElement
IfcSite (Far away sites)
IfcGeographicElement or IfcBuilding depending if the site is mostly terrain or building.
Alternatively I use only raw geometry for this site, which also seems to work well.
Hi, As per what I said yesterday, I’m pretty sure that you will get odd results…
From my understanding, you can only have one ifcSite component, but it can have multiple IfcGeographicElement sub components. All the buildings must be on the same hierarchical level as each other, just within the ifcSite component. Of course you can attribute multiple Tags/layers to each object as you see fit.
But heh, I could be wrong, maybe @brewsky or @rtches have an opinion ?
It seems I can even have a site inside a site, or at least BIMvision accepts that. (I should try on other BIM visualizers or on Trimble Connect though. : )
Yes, BIM vision allows you to do that, I’m just not sure how it’s handled by other software… if you send your ifc to somebody who uses R_vit or Arch_Cad for example, does the structure get recognized ?
I haven’t had time to go & look on the buildingSmart site to see if there are “rules” on this ? But heh, if it works, that’s cool !
Revit and Archicad are probably the staple for what we can do with an IFC model exported from Sketchup, but with the following apps it seems to work fine (I’m not talking about full classifications, types, psets and other data, which might be a long way from being OK).
That will surely state so many errors that I won’t be able to navigate. I have to dive into construction elements a bit better. Still stuck on dealing with the transition from my overall Sketchup worfklow to IFC compliance.
yeah, it was pure curiosity - the checker systematically finds things it doesn’t like in my files, but they’re so obscure I don’t really know what its ■■■■ issue is !
Like this for instance
I mean we have no control in Su over this as far as I know, so until the folks at Trimble fix this kind of issue…
And yet, it doesn’t stop me from exchanges with my engineers/contractors and I’ve built plenty over the past nearly decade doing what I call DIY BIM !
It would just be nice to have green tick boxes on our files