BIM Drawing Structure

[Diamond]

Hello,

This is probably a question for Jeffrey W Ouellette (the BIM-ologist in residence).

I have been reading the BIM in Practice page on the Nemetschek Site, and are trying to work out how what is best practice for the setup of layers, and how are objects translated in the IFC export?

Are they translated through the IFC entity classes, or through VW classes?

Do the objects have inherent IFC classes, or do we need to add them?

Years ago (back in VW 11 days) I was sure I read that when building a building model it was advised to have a separate layer for the floor. It seems Jeffery you are advocating this in your White paper with the slab & structure going on this layer. I have been doing something similar for some time, but wanted some clarification.

Are there any other VW materials for some more reading on this topic?

Thank you.

[Jeffrey W Ouellette]

Troy,

What I hoped to get across in the Ellicott Heights white paper was that the Vw organization of a project can vary, dependent on the size and complexity of a project. You have to design the process and all the parts - size of team, responsibility of team members, data structure (level-based or function-based), file/folder structure, referencing system, etc. - before you even start creating model data.

As I create more research models, resulting in more BIM in Practice material to be released in the future, I am constantly learning and thus tweaking ideas and recommendations for doing BIM in Vw. So take my following advice as a reflection of what I know today and have learned from the past.

IFC is a means/file format/schema describing BIM data. In Vw, the IFC expression of building elements such as Columns, Walls, and Floors, runs parallel to the Vw internal data structures. The IFC data is mapped directly to objects, not by Vw Classes.

At export, we automatically map the Vw data to IFC data formats. In Vw Architect 2010 SP3, this includes automatic IFC mapping for the following Vw entities:

Base Cabinet, Bath-Shower, Ceiling Grid, Clothes Rod, Column, Comm Device, Compartment Sink, Counter Top, Desk, Door, Drilled Footing, Simple Elevator, Escalator, Fireplace, Floor (as IFC slab), Framing Member, Grab Bars, Guardrail (Curved & Straight), Handrail (Curved & Straight), HVAC Damper, HVAC Diffuser, HVAC Elbow Duct, HVAC Flex Duct, HVAC Outlet, HVAC Splitter, HVAC, Straight Duct, HVAC Transition, HVAC Vertical Duct, HVAC Vertical Elbow, Incandescent Fixture, Mullion, Parking Spaces, Pilaster, Pillar, Ramp, Receptacle, Roadway (all types), Roof, Roof Face, Seating Layout, Shelving Unit, Space, Stair (and Custom Stair), Switch, Table, Tables and Chairs, Utility Cabinet, Wall Cabinet, Round Wall, Wall (and Wall Projection/Recess), Window,

Window Wall (Straight & Curved), Workstation Counter, Workstation Overhead, Workstation Panel, Workstation Pedestal

In addition, symbols in the following content libraries are also automatically assign basic IFC data:

Architect Sampler.vwx, Equip-Office Equipment.vwx, Equip-Residential Appliances AGA Ranges.vwx, Equip-Residential Appliances SubZero USA.vwx, Equip-Residential Appliances Wolf USA.vwx, Equip-Residential Appliances-Audio Video.vwx, Equip-Residential Appliances-Imp.vwx, Equip-Residential Appliances-Metric.vwx, Equip-Restaurant Equipment-Imp.vwx, Fixtures-Imp.vwx, Furniture-Furnishings and Scenic Elements.vwx, Furniture-HMI-Modern Classics.vwx, Furniture-Knoll.vwx, Furniture-Misc-Imperial.vwx, Furniture-Misc-Metric.vwx, Furniture-Office.vwx, Furniture-Residential.vwx, Furniture-Systems HMI-Typicals.vwx, Furniture-Systems-Imp.vwx, Furniture-Systems-Metric.vwx, Openings-Windows Velux Skylights.vwx, Electrical-Lighting Fixtures Int & Ext.vwx, Electrical-Lighting-Imp.vwx, Electrical-Panels-Imp.vwx, Electrical-Panels-Metric.vwx, Electrical-Power Devices-Metric.vwx, HVAC-Equipment-Imp.vwx, Sanitary-Fixtures.vwx, Sanitary-Kohler Baths.vwx, Sanitary-Kohler Bidets.vwx, Sanitary-Kohler Faucets.vwx, Sanitary-Kohler Lavatory Sinks.vwx, Sanitary-Kohler Showers.vwx, Sanitary-Kohler Sinks.vwx, Sanitary-Kohler Toilets.vwx, Sanitary-Kohler Whirlpools.vwx

Please note that in many cases the IFC data that is attached to an object is NOT completely comprehensive of all IFC Entity and Property Set (Pset) data associated with a BIM object. A user is able to edit/override/add IFC data to any object using the "IFC Data..." command in the AEC menu.

As far as the overall Design Layer structure of the BIM, I am now leaning more toward "Less is More". I would have just three (or four) layers for each story/level; Mod-Floor-#, for architectural floor planning elements,(optionally a Mod-Ceiling-#, for architectural ceiling plane elements,) Mod-Structure-#, for structural elements including floors, columns and load-bearing walls, and Mod-MEP-#, for MEP/HVAC systems and elements.

Through this structure, you can maintain the internal flexibility of setting up drawings in Vw while simplifying export in the IFC Export dialog. Also, it simplifies the IFC import of data from structural and MEP engineers, giving you a placeholder layer, independent of the architectural design/elements.

Edited May 18, 2010 by Jeffrey W Ouellette

[Diamond]

Thank you Jeffery for that breakdown on the IFC data. Very helpful.

I know what you mean by less is more. I am struggling with that as well, as others coming across my drawings find the multi-layer set-up confusing. Especially where everything is in the one drawing. Having worked in smaller projects this hasn't been a problem, but in a larger office on a larger project, breaking up a project is so important.

I liked what you had to say about one person generating a model, and others detailing from the model in the viewports (instead of in another drawing whilst I am modelling, as is happening with the project I am working on at the moment). I think this was the single most important mind shift/productivity tip that I have had after reading the Ellicott Heights white paper. This and breaking the floors up into individual files. I think that would prevent a lot of confusion for those that find the multi-layer per level set-up confusing as noted earlier.

In your less is more layer structure, you don't mention your grid layer. Where does this information go now?

Thank your or your prompt reply. Really good stuff.

[Jeffrey W Ouellette]

Troy,

I've usually got other layers for other "supplemental" information. Typically, I use a "Mod-Guidelines" layer to put the structural/building grid (class='Structural-Grid') and maybe other important alignment guidelines that don't fall on the grid (class='Non-plot').

In addition, if I have a site model, I may have a "Mod-Site" layer. This will either contain the actually DTM or just a reference from another file (or even a Design Layer Viewport from another layer in the file).

[Diamond]

Jeffery,

Yes that is what I do as well.

When splitting your building up so that each level is an individual file, how do you deal with the stair tool? The stair tool allows for an upper and lower floor, or do you have to forgo this for the sake of file organisation?

[Jeffrey W Ouellette]

Troy,

Yes, I usually end up forgoing the linked layer capability of the Custom Stair tool. Instead, the "new" Stair tool (as opposed to the "old" Stair tool, which is now the Custom Stair tool) has an option for 2D or hybrid. When I want specific 2D graphics to show the stair above/below, I'll insert a 2D stair underneath the 3D/hybrid one and adjust both graphics. I admit it is not ideal, but the new Stair tool doesn't have the layer linking functionality, yet.

[Jeffrey W Ouellette]

Also, depending on the size of the project, it may not even make sense splitting it up by level. Instead, you could set up a complete central file of the building "shell" and then reference in interior configurations, independent of the exterior walls and structure. From the interior files, you would then reference in the respective portions of the shell file.

I find that using the BIM tools in Vw makes it easier for one person to do a lot of related work (e.g. exterior wall/form design) and that artificially chopping up the model into many pieces (like stories/levels) may actually create more work, not less.

[Diamond]

Thank you for that. I thought as much.

Now with so much intelligence in the Parasolid engine, is there any plans for clash detection? Or will that be left up to apps like Solibri?

And how do you tend to deal with curved (in plan) buildings with slab & roof objects showing facettes where walls and nurbs and extrude based object do not? It seems I spend no end of trying to get around this. I love the 2D/3D hybrid objects and how they show in plan, but they can really mess up hidden line presentations when all of those facets come out. Besides modelling the roof and drawing polygons over for plan view I am not sure what to do.

I apologise. I am all questions.

Oh yeah. Happy 100 posts to me!

[Christiaan]

I find that using the BIM tools in Vw makes it easier for one person to do a lot of related work (e.g. exterior wall/form design) and that artificially chopping up the model into many pieces (like stories/levels) may actually create more work, not less.

Now if we could just have a client/server system where one can sign in and out any arbitrary part of the model we wouldn't have to worry about all of this.

[Jeffrey W Ouellette]

Now if we could just have a client/server system where one can sign in and out any arbitrary part of the model we wouldn't have to worry about all of this.

Of course, HE had to chime in....

[Jeffrey W Ouellette]

Troy,

Enable the option "Mesh smoothing with crease angle:" in your Document Preferences. Set the value to "1" to start, then increase it a bit to see if you can get the results you want.

As our Parasolid implementation matures, I sure we will all see improvements of various aspects of the application. Just give it time...

Clash detection is somewhere on our radar, but in the meantime, I think using Solibri, or even Navisworks, is an even better (though expensive) solution. These apps are really purpose-built for these kinds of processes and give the user the power to tailor the details of clash detection.