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Revit & BIM


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Browsing the book store the other day, I looked through a copy of a book Introducing Revit. It was interesting and brought up some questions about detailing in BIM software.

If you cut a section through a modeled building and use it for detailing, will the software automatically fill in the details, or will you have to draw them in yourself? The book noted that you can set different levels of detail in a model and this brought my question to mind.

Vectorworks doesn't fill in detail sections and we have to complete them ourselves, even when we use the provided wall tool. I suppose this makes VW not a true BIM software.

My impression of the gallery of renderings in the Revit book was not very good. They seem to lack realism. Maybe it was that I didn't like the designs. Also, the drawings lack a personal touch which is unfortunately true in most of the renderings I've seen.

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David,

Bite your tongue!! ;) VW is a "true" BIM package. Contrary to what others may think or tell you, the differences between BIM authoring packages are NOT that fundamentally different. Some exploit certain features/workflows more effectively than others, but in general, they all work toward the same purpose/goal.... information modeling. That means, not just 3D, not just automated drawings, but an integrated, virtual construction where geometry understands "what" it is, "where" it is and has relevant data attached to it.

I don't know of any of our competitors that "automatically" fill in all the details. This is NOT a requirement of BIM. I think that there is a misunderstanding between what "detail" means in the BIM vs. an architect's expectation of detail is.

In many cases, you can control the level of modeled parts in a BIM, where more parts make it a more detailed model and thus get richer automated views. But even with a more robust modeled BIM, the level of construction detail needs to be controlled by the user/designer/architect in a separate view.

In all cases, the user supplements the automated sections/views with 2D linework and notation to create the drawing details everyone is familiar with. Why? If you literally modeled every piece and part of a building, all the way down to flashing and fasteners, you would have an extremely large model and incomprehensibly complex database to manipulate (read: REALLY BIG=REALLY SLOW). Then, you would have to determine the best automated notation (notes/dimensions) system to further enhance views (details, plans, sections, wall sections, etc..).

The best BIM system give the user the power of the information modeling and the flexibility of drawing, when needed. Until the requirement (and need) for paper CDs is completely eliminated, the power of drawing will be very important to the transmission of information from the designer to the rest of the world.

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Eliminating paper CD's could happen, in time. It all depends in certain advances, not only in software's but hardware's. Maybe an "electronic paper" or something like that.

There are many architectures today that requires 3d, for efficiently manage its conception and construction. Like the Chanel Mobile Art by Zaha. Which is, basically and digitally speaking, a piece of Nurbs. Same for the Nest from Herzog. Not always valid for the most common Architecture.

What you're actually describing is lack of solid modelling. But solid modelling isn?t BIM. The focus of BIM is to provide building information. Solid modelling can be incorporated into BIM but it isn?t a requirement. That?s my understanding of it anyway.

Christian: I think, one of the most powerful features of Vw is the solid modeler, and the abilities of attach records to it + classes. Those features let you make any object an Information Container, full of geometry from the Modeling engine, and graphics attributes from the classes. I think that's one of the things people does not understand, not necessarily you, about Vw.

Edited by Mr. Gog
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If you cut a section through a modeled building and use it for detailing, will the software automatically fill in the details, or will you have to draw them in yourself? The book noted that you can set different levels of detail in a model and this brought my question to mind.

Vectorworks doesn't fill in detail sections and we have to complete them ourselves, even when we use the provided wall tool. I suppose this makes VW not a true BIM software.

I know that the Section Viewports in Vw Architect will show wall components (Vw Fundamentals probably does not have this).

As it has been said, Vw is classifiable as BIM, especially after incorporating the IFC classes, although it has not been fully certified by the US Govt.'s General Services Administration yet. There are no set BIM standards from the GSA yet for building model exchange among clients and professionals, but they have drafted out some 3D BIM model guidelines. But philosophically, BIM can be practiced in 2D drafting (AutoCad, Allplan). What I really like about Vectorworks is the flexibility in jumping from 2D to 3D, and even generating 3D objects from 2D drawing. And despite all of the governmental hubbub over BIM, I have not yet had to bother with IFC's or the GSA. So maybe the AIA's demand to "use BIM or die" was a hollow threat.

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You need to recognise that BIM is a moving target and one man's BIM is another's nightmare. BIM is about the digital definition of a building so that all parties involved in building it and running it and ultimately disposing of it have a common model from which the information they require can be extracted and used. There - how vague was that :)

In terms that most understand, it is usually about creating a 3D model of a proposed building design, extracting drawings from that model, and providing the ability to add non geometric information to the elements in the model (such as details of finishes, cabling, materials, and environment. From that combination of geometry and information the building user/designer can pull out the detail they need and run it into other applications that provide details on structural integrity, ventilation, energy efficiency, carbon footprint etc.

Vectorworks is aiming at the front end design side of BIM so the modelling and drawing production and ability to add information to elements is key. In this respect VW is already a very capable BIM application. The 3D modelling now surpasses most if not all of the AEC competitors. The drafting and drawing is second to none, and the ability to add information can be done in a variety of ways from automated plug ins to manually added data.

As to the question of 2D to 3D integration VectorWorks is probably as good as any of the so called BIM applications out there at creating drawings from the 3D data. But in fact ALL the AEC systems lag way behind what most MCAD systems currently do in this respect.

The problem with any 3D to 2D is that to have the drawing detail you need to model the detail in 3D. In MCAD systems this is actually usually necessary due to manufacturing or operational considerations but even here shortcuts are taken. For example, you would not model the thread of a screw. There is no need to except for visualisation purposes. For the drawing the screw would be represented by standard ISO drafting schematics (and these are generated automatically by the MCAD systems for holes and threads - as indeed they are by VW screws and holes).

Furthermore, if you do try to model everything in minute detail you will end up with an unusable file and very quickly go bust!

What Vectorworks lets you do is use the 3D model to flesh out the bulk of the drawing, and then use either DLVPs or SLVPs to manually add the details. This approach works well provided you keep the limitations in hand. The main ones being that currently you cannot have section viewports on design layers, so all sectional work needs to be either done as sheet layer viewport annotations or as 2D in the design layers. For some this is not an issue but if you need to export to dwg it is a big issue as viewport annotations in sheet layers do not appear in model space in autocad and so are, effectively locked.

Si is VW a true BIM application, yes, definately. Can it provide fully detailed construction drawings from the 3D data automatically? No, but then either can any other system, regardless of what their marketing blurb says.

What you get with VW is a good combination of tools to mix and match to do your job efficiently. And those tools can only get better now that parasolid is being used. FYI Autodesk products use ShapeManager which is based on ACIS (well OK it WAS ACIS until about ACIS version 8 when Autodesk opted out (taking the source code with them). ACIS is good but parasolid is more robust (I have apps based on both and the parasolid ones just model better).

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A really interesting discussion. Thanks to everyone for your input.

I was under the impression (silly me) that a BIM package would not only keep track of the materials through a database, but would also make detailing automatic, at least so that you wouldn't have to go in and do a lot of manual drawing.

So, in practice, it's still necessary to manually fill out sections that are generated from the model? And if the model changes, you have to go back and revise the manually drawn lines. Sounds like the old AutoCad days.

I know that the VW sections' detailing is minimal at best. But I was assuming that something like Revit would at least show the components that make up a section. I suppose that in time, with enough computer power, more detail will be available.

I had a boss once with no AutoCad experience who thought that details would be automatically generated from simple section cuts. He was way ahead of his time.

The other matter that I am concerned about is the overall ugliness of typical 3D renderings, a lack of human scale or detail. The designs may be limited by the software. Seems more than likely that the cost of construction doesn't permit any "art" beyond the expression of materials or structure. Is the architect limited by software? People like Frank Gehry can get crazy with their designs, but they don't actually get involved with the computer. Others do it for them.

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just for the fun of it i have a project that i am trying to push the envelope with vw.

the attached is a 3" detail from the model. no 2d was involved.

the gwb is a wall

the ply is a wall

the bottom plated are walls

the masonry is a wall

etc

i know this may be overkill but i just wanted to see how it would work out.

i do think that KQ has hit it on the head though.

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With all due respect to the AIA, Nemetschek, Jeffrey, etc., I have yet to be persuaded about the utility of BIM for most projects.

I can see that it may be useful for projects which are very large, very complex, and/or very repetitive, but the vast majority of projects built do not fit this profile. For the typical projects our structural firm works on (high-end residential, light commercial, schools, etc.), there's no sufficient justification for the significant increase in both fee and timeline that BIM modeling would require.

I think Jeffrey says it well when he calls a BIM model, "an integrated, virtual construction..." If there is complexity or scalability enough in a project to warrant assembling a building twice, once digitally and once physically, then it's a great tool. In my experience, though, this does not describe most projects.

We will probably get to that point someday, but I suspect it's farther off than most think. As far as I can tell, too many of the tools which would get us there (3D collision detection, simple yet robust tools for information tagging, etc.) just aren't developed enough. And I think you have to be pretty removed from the construction process to think that paper will be succeeded as the default medium for plan check submittals, on-site use, etc. any time in the near future.

Two cents from an engineering perspective...

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I agree that using BIM on most smaller projects is not a cost-effective investment, but there are other benefits to using BIM on large projects than what has been discussed so far. Hopefully I won't take this thread too far off track:

I have heard that some General Contractors here in the States have started training on Revit and other BIM packages for their own in-house use, whether or not the project was designed in BIM. As it was explained to me, their intent is to use BIM to find conflicts in the Contract Documents so that they can identify potential Change Orders in their bid.

I think that everyone can agree that there is no such thing as a 'perfect' set of contract documents, and this example outlines a situation where those imperfections can be exploited. The potential of BIM is to discover those imperfections before they have a financial impact.

Regards,

Tim

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