Article: "Not All BIM is Parametric"

[Scott D Davis]

Cadalyst has published an article titled "1-2-3 Revit: Not All BIM is Parametric" which was written by Rick Rundell, AIA, of Autodesk. Very good article to test if the "BIM" software you may be using is really parametric.

Here's the link:

http://aec.cadalyst.com/aec/article/articleDetail.jsp?id=146865

[Scott_Bloss]

Hey Scott this is a good artical thanks for posting it.

[stefan.boeykens]

To answer the survey the best I could in the few programs I happen to know something about...

1) Does your software use you to coordinate and manage change?
Revit = no
ADT = partly
ArchiCAD = no/partly

2) Are the terms "extracted" or "generated" used to describe the creation of drawings?
Revit = no
ADT = partly
ArchiCAD = no/partly

3) If you slide a section key across a plan view, does the section update immediately?
Revit = yes
ADT = yes
ArchiCAD = yes

4) Does the BIM solution rely on "smart" or "intelligent" objects?
Revit = yes
ADT = yes/partly
ArchiCAD = yes/partly

Now who writes such a text? A Revit defender.
And where does it say that the only good BIM solution is a 'parametric building modeler TM'?

This is not an article. It's a sales presentation.

[hand471037]

3) If you slide a section key across a plan view, does the section update immediately?
Revit = yes
ADT = yes
ArchiCAD = yes

Hold on there. What he's saying isn't that the section is generated, it's that the tag for one section shows up automatically on the other sections. For example, if I've got a South Elevation for my building, and I draw a Whole Building Section on the Floorplan that's looking West, do I then automatically see a Section Tag added to said Elevation, in the right place, pointing the right way, and tagged correctly- without having to do anything?

That's a big difference. We all know that all three systems will create sections automatically. Not all three systems however automatically coordinate the View Tags like Revit does, which is a major selling point of the software.


Now who writes such a text? A Revit defender.
And where does it say that the only good BIM solution is a 'parametric building modeler TM'?
This is not an article. It's a sales presentation.

'defender'. Heh. Who's slinging loaded comments now? When you say things like that it's hard to take you seriously. I mean, it looks like you're the one that's insecure here, suddenly posting into the middle of a Revit forum, saying that something pro-Revit is nothing but propaganda, and signing your message that you're an Archicad user. Instead, why don't you talk about something useful, like what Archicad can do that Revit can't. For the firm I'm at now tied to use Archicad, and it was such a dog (version 8 ) that they abandoned it for Revit. And they were trying out Archicad for ADT couldn't live up to it's hype and were looking for something better. So if things have gotten that much better on the ADT / Archicad side of things, or you've figured out how those systems could work better than Revit for us, man, I'm all ears. seriously.

FYI, Rick Rundell is head of Revit Marketing. So you have to take this with a grain of salt. But it's a real article, for it's getting at the heart of the matter: That a lot of systems are calling themselves 'BIM' and 'Parametric' when they are only kinda like that, and only if you know them well and use them in a certain way. As a long time Revit User, I have to say that I've been frustrated at times when people who have never really used Revit miss the point that there are a few things about it that are fundamentally different, and think that ADT or Vector works or Archicad are 'just like Revit'.

And he doesn't say that the only good BIM solution is the Parametric one. He's clarifying what a 'parametric building modeler' really is, why it's different, and why it can be a really good thing for some folks.

[Steve_Stafford]

This is not an article. It's a sales presentation.and...Graphisoft or someone who works for them has never written something that favors their product?

Sure it is obvious that the definition of parametric behavior that Rick uses is Revit minded. But that definition is what sets it apart from your favored one. I think (not surprisingly) the post by Leonid Raiz (one of Revit's founders) in our FAQ is the best summary of Bi-Directional Associativity (parametric behavior) and what makes Revit stronger than the rest A LINK (http://forums.augi.com/showthread.php?t=12813). Your own forum members are asking for some of these features in ArchiCAD as well.

Guess it comes down to your definition of parametric and BIM? I could get into how that relates to our past President...nah... ;)

[stefan.boeykens]

Hold on there. What he's saying isn't that the section is generated, it's that the tag for one section shows up automatically on the other sections. For example, if I've got a South Elevation for my building, and I draw a Whole Building Section on the Floorplan that's looking West, do I then automatically see a Section Tag added to said Elevation, in the right place, pointing the right way, and tagged correctly- without having to do anything?

That's a big difference. We all know that all three systems will create sections automatically. Not all three systems however automatically coordinate the View Tags like Revit does, which is a major selling point of the software.
The answer for ArchiCAD is 100% yes.
If you move the section on the plan, the section "drawing" will be updated. If you drag the side point of the section, the section "drawing" will be clipped.
You have the option to "unlink" the section drawing from the 3D model, but I have never felt the need to do that in ArchiCAD.

And that's the way it should be: the section symbol on the plan view IS the section.


'defender'. Heh. Who's slinging loaded comments now? When you say things like that it's hard to take you seriously. I mean, it looks like you're the one that's insecure here, suddenly posting into the middle of a Revit forum, saying that something pro-Revit is nothing but propaganda, and signing your message that you're an Archicad user.
I am an ArchiCAD user, with working experience in AutoCAD and VectorWorks and main knowledge (not real working experience) with ADT, Arkey, Microstation and Revit.
And be sure that I am interested in Revit, much more then ADT. Otherwise, I wouldn't be here.
I agree with the 'loaded comments' part, though. But if an article is describing the world from a very narrow point of view, the article is certainly not objective. And that is precisely what I expect from articles.

Revit is always called the "Parametric Building Modeler", but that's a marketing term.
ArchiCAD uses the term "Virtual Building" and that's marketing too.

Anyway, don't take it too hard. I'm here especially for comparisons, just as Scott is at ArchiCAD-talk to do that. And he somehow seems to survive these discussions (probably because Revit is good and he knows his stuff).

[Scott D Davis]

Stefan,

I think what Jeffrey was eluding to, is that in Revit, if you place a section marker in plan, the same section marker will also show up in any other view where that section applies. If you place it in plan, and then switch to an elevation that is perpendicular to the section, you will see the same marker, but now oriented vertically in elevation. If the section is placed on a sheet, all the section callouts for that section update with sheet number and detail number. If you move the section, all markers and the section drawings themselves update instantly.

Does ArchiCAD do the same? Or do you need to place another marker for the same section in the other relevant locations? How long does it take to update a section if the marker moves?

[Wes Macaulay]

Yes indeed... our man Rick is another part of the Autodesk sales machine.

But he's right. I'm not going to slight ArchiCAD here... because it at least is very close to Revit. Instead I'll reserve that for my favourite whipping-boy: Vectorworks. This program makes graphically good-looking 2D CAD drawings, and while it has great 3D modeling capabilities, the developers have the gall to call it a BIM product.

It's not.

Sections and elevations are dead. If you want multiple users working on the different stories as part of a building model paradigm, then you have to model each floor in a different file, and VW users will tell you what they think of workgroup referencing, which is similar to ADT xrefs.

Sections and elevations generated in VW are worse than ADT. It's disgusting that they've hijacked the term. It's $1500 CDN compared to about the 5 or 6k that Revit costs up here, so everyone thinks it's a bargain. It is amazing how often people compare software on price alone!

All software is the same right? We should just get the cheapest one!

:banghead:

[stefan.boeykens]

Stefan,

I think what Jeffrey was eluding to, is that in Revit, if you place a section marker in plan, the same section marker will also show up in any other view where that section applies. If you place it in plan, and then switch to an elevation that is perpendicular to the section, you will see the same marker, but now oriented vertically in elevation. If the section is placed on a sheet, all the section callouts for that section update with sheet number and detail number. If you move the section, all markers and the section drawings themselves update instantly.

Does ArchiCAD do the same? Or do you need to place another marker for the same section in the other relevant locations? How long does it take to update a section if the marker moves?
In ArchiCAD you draw a section "symbol" on the planview (and only there) and then a seperate section view becomes available. This is a "generated view", but each "line" you select actually gives you access to the real object. You can change objects in the section view. It's not realtime and not so instant (at least not on my old computer - it's not installed on my new one yet). It works fine, unless you enable vectorial shadowing in the section view and combined with vectorial hatching. It can generate very clean and legible drawings but at a cost of a longer generation time. And trees with lot's a polygonal leaves can slow things down considerably. In fact, I sometimes do the finishing of the drawing in a view without shadows and hatching and only re-activate them for the final plotter drawings.

The section line is not visible in other sections. It's visible on all plan views.

You can generate clipped 3D views as well (a perspective setting).

There is a far and near setting, which enables elements with three looks:
- the section plane, using material hatches or using one single fill and a fat line
- the near elements in a medium line
- the far elements using a thin line
Very graphic but gives strange effect with sloped roofs...

And vectorial shadows can be calculated from the sun or from an arbitrary angle.

In fact, the whole section drawing can be almost fully complete from the 3D-model. You usually add text and dimensions and some smaller additional lines or hatches to finish up your drawing, but nothing major. Sections through windows correctly show the window reveals, which is a common building practice in Belgium.


[...]But he's right. I'm not going to slight ArchiCAD here... because it at least is very close to Revit. Instead I'll reserve that for my favourite whipping-boy: Vectorworks. This program makes graphically good-looking 2D CAD drawings, and while it has great 3D modeling capabilities, the developers have the gall to call it a BIM product.
VW is a fast and efficient drawing program with 3D modelling tools. It's definitely not BIM ;)
It's not as expensive as the others so it fits into the market rather well. It's popular in Belgium.

[gravelin]

This is a "generated view", but each "line" you select actually gives you access to the real object. You can change objects in the section view.
Thank you for all your informations.
Can you precise these points ?

In this generated view, can you
Change the type of wall or windows ?
Move a wall retaining the wall's joins ?
Place a new door or windows in an extiting wall ?

If you do it, what do you need to do yourself to guarantee the coordination of all plan views, sections, elevation, schedules and sheets ready to plot ?

Merci pour toutes ces informations.
Peux-tu préciser ces queslques points ?

Dans ces "vues générées", peux tu
Changer le type de mur ou de fenêtre ?
Déplacer un mur en conservant les jonctions entre les murs ?
Ajouter une nouvelle porte ou fenêtre dans un mur existant ?

Si tu le fais, que dois-tu faire pour garantir la coordination de toutes tes vues en plan, coupes, élévations, nomenclatures et feuilles de mise en page prètes à l'impression ?

[stefan.boeykens]

> In this generated view, can you
> Change the type of wall or windows ?

yes

> Move a wall retaining the wall's joins ?

No. ArchiCAD doesn't know such connections. It automatically cleans up wall and floor connections, but it doesn't make a real link, meaning moving a single wall doesn't alter the connected walls.

> Place a new door or windows in an extiting wall ?

Partly... You can't directly create a new window or door in such wall, but you can copy paste existing windows around. A bit cumbersome.

> If you do it, what do you need to do yourself to guarantee
> the coordination of all
> plan views,

Nothing. They are the same building model.

> sections, elevation, schedules and sheets ready to plot ?

Update/regenerate (= let the computer work)

[ppelegrin]

>
> sections, elevation, schedules and sheets ready to plot ?

Update/regenerate (= let the computer work)


Hi Stefan.

And if Bill Shorten is around I invite him to comment as well. With a genuine interest in getting the facts right on ArchiCAD, can I please ask you to comment on the following items, and forgive me if I demonstrate any ignorance:

Can a working/construction drawing be generated without plotmaker? Many ArchiCAD users often refer to the ability of ArchiCAD being live just like Revit, I wonder if this is due to confusion of the terms 'drawings' and 'views'. Let me suggest that a view is simply another 3D view of the same model, used while designing/creating your model. I can appreciate that views in ArchiCAD would be live and instantaneous, am I right to assume that views in ArchiCAD are simply seperate 'windows' in your design interface, different to working/construction Drawings?

Is the 2D drafting (annotation, dimensions and linework) created within Plotmaker?

How are dimensions, annotation and 2D linework applied? If any of these are added after the drawing is generated, what happens after these are regenerated due to a change in the design, using small and significant changes as examples? Appreciating that say the position of an annotation tag, "East Elevation" is unlikely to affected by a design change.

Bill Shorten and many other ArchiCAD users respond to Revits ability to have 'live' drawings with the statement that ArchiCAD has this same feature, Quoting Bill from another thread: "yes, you 'can' unlink elevations and sections but if you don't then the views are fully bi-directional". Can you please expand on Bills comment, what are the normal factors in requiring these to be unlinked?

My experience with 3rd party Architectural ACAD add-ons was that at some point in a project, preferably when the design changes were minimal and drawing production was the focus, we would begin to unlink the views which were converted into working drawings; effectively breaking the link between the 3D model and the working drawings. With this system, it was often inpractical or impossible to automatically manage a change from the 3D model back into these drawings (or regenerating them) without the need to lose small or large amounts of drafting - how does this compare with ArchiCAD?

And lastly, reading on the ArchiCAD forums, there is reference to Open GL views, what are these and how are they different, if at all, to a normal view - does this relate to specific 3D views or is it a system configuration item, for general performance improvements. I assume this is not related to Plotmaker?


Regards
P Pelegrin

[Marek Brandstatter]

I think Leonid Raiz articulated quite well the significance of "full bi-directional associativity between all 3 main classes of elements" in Revit. The Parametric BIM test becomes somewhat more stringent.

ArchiCAD 9 http://forums.augi.com/showthread.php?t=8021

"There is some amount of confusion regarding full bi-directional associativity and it may be useful to spell out what it means. I don't really want to focus on the "my software is better than yours" aspect but would rather describe the meaning of terms "live" and "bi-directional associativity". Any product making claims to support bi-directional associativity has to be able to support examples of parametric and associative changes listed below.

Many existing products have some ability to update elements of a design when other elements change. However with an exception of Revit in many cases such updates are not automatic. Every case when a user has to take an explicit action to do an update creates a possibility of error and uncoordinated design documents. It also necessitates additional work by an end user. We also should not confuse the ability to display or edit a single underlying data model in multiple views with full parametric associativity between various elements of design.

There are 3 main classes of elements in any building design
(A) Building components (walls, roofs, doors, windows, floors, etc.)
(B) Views including schedules and sheets
(C) Annotations (text notes, dimensions, spot elevations, etc.)

I do not want to diminish benefits of other products, they are quite good at what they do.
On the other hand Revit is the only product on the market today which was engineered from the ground up to provide full bi-directional associativity between all 3 main classes of elements.

Below are the examples of this associativity and corresponding parametric change propagation from elements of class to another.

Building components to building components
a. Move one wall and connected adjacent walls adjust to become longer or shorter
b. Move walls and a floor adjusts to cover area enclosed by walls
c. Raise/lower a roof and attached walls grow or shrink
d. Thicken a wall and door frames adjust to new thickness
e. Raise a level and all elements placed of this level will follow.

Building components to views
a. Change to a building component is automatically reflected in all graphical views without additional user actions
b. Move walls and room schedule updates room areas
c. Add or remove building components or change parameters of existing elements and schedules update automatically

Building components to annotations
a. Change geometry and dimension value updates
b. Move things higher or lower and spot elevation reflects new heights
c. Move walls and room tags update displayed area values
c. Changes to properties of wall, windows, doors, etc. are automatically reflected in their tags

Views to building components
a. Any graphical view (plan, elevation, section, callout) may be used to effect a change to building component
b. Changes to building components may be made by editing their parameters in schedules
c. Changes to view phase or level of detail automatically reflected in display of all building components shown by this view

Views to other views
a. Move section or detail view backward or forward and callouts move with their parent section
b. View and drawing schedules (view/drawing lists) may be used to change properties of other views and drawing

Views to annotations
a. Change view scale and all dimensions, text notes, etc. adjust to maintain their sizes on printed output
b. Place a view on a drawing sheet and view tags update to reflect sheet number
c. Change view scale and scale tag in view title on sheet updates

Annotations to building components
a. Change dimension value and building component changes accordingly
b. Changes to property values shown by tags automatically propagate to building components
c. Change elevation value displayed by level tag and level moves up or down
d. Impose dimension equality constraint or lock dimension value and building components behave accordingly

Annotations to views
a. Flip direction of section view tag and view forward direction flips.

Annotations to annotations
a. Change sheet number in a titleblock and the change will propagate through drawing to views placed on this drawing and then to their view tags (section and callout heads).

All these examples are made possible in Revit not only because it has a patent pending Parametric Change Engine (PCE) in the middle of its software architecture but also because all Revit's elements are implemented with parametric change in mind. There are countless other examples made possible by the PCE and the unifying notion of associativity between all 3 kinds of design elements.

Unless a product is implemented from the ground up with a PCE type of architecture its implementation may exhibit some examples of associativity but its change propagation capabilities are bound to be limited. "

[hand471037]

But if an article is describing the world from a very narrow point of view, the article is certainly not objective. And that is precisely what I expect from articles.

Then you shouldn't be reading articles in CAD magazines. ;)

There are a *lot* of misleading, half-truths, and misinformation within the CAD magizines. I blame a combo of lack of understanding (many times the person writting the article has no practicle experance with the tool in the field, or is many years removed from doing real work by just being a CAD expert for the last few years), marketing (the articles, like this one, are written by employees of the parent company, or the larger company directly supports the mag in ad revinue so they can sway things the way they want- see CADATLIST & Autodesk IMHO), or just simple lack of understanding (it's not like the folks writting the articles have that much time to delve fully into the software & keep up within everything).

With that said, I still think this article is approate, and not outright propaganda. The point here is that Revit *is* different than other BIM systems, at a fundamental level, and I beleve this article is trying to address that. Yes, it's biased toward Revit and Revit's way of doing things, as it's written by someone who's been with Revit since the start. But to get upset that it's not objective enough, when lots of the CAD press is a lot worse IMHO is, well, like getting upset at Fox News over something.

Take what info in useful, know that all sources of information are biased and tained, always think about where the info is coming from and don't take any wooden nickles. :D

[Gadget Man]

Until now I wasn't exactly convinced that I made a good choice switching from ADT to REVIT, about a year ago. I mean , for sure ADT is no good, but is REVIT the right choice..?

Throughout most of my posts here, I expressed various degrees of dissatisfaction with REVIT (and undoubtedly it will still continue, for if I am not happy with something, I'm not happy..) but after reading this thread I finally (I think) made up my mind!

I MADE THE RIGHT CHOICE...! (Not that it really makes any difference to any of you :wink: ...)

Thank all of you for this fantastic thread !!!!!!!!!!!!!! It surely clarified many things for me and I will try to be much more patient in recognition...

Jerry.

[beegee]

>>(Not that it really makes any difference to any of you :wink: ...)
.

That's harsh Jerry :shock: .
We DO care.
That's why most of us are here. To spread the word. And the word is Revit. ( here endeth the sermon... )