Thursday, March 30, 2006

Who Wins? A Battle of Constraints

Using multiple constraints Revit can find itself caught in the middle. As a result some constraints will take precedence over others. Objects that are aligned will override length constraints.

If you apply both an alignment and length constraint Revit will complain that it cannot maintain both kinds of constraints. You can choose to remove the constraints. Revit will remove the length constraint and try to keep the alignment constraint.

This image portrays windows that are aligned and locked to each other and the first window has a locked dimension to position it near the wall.

Next we try to move the last window on the top right.

...and Revit complains...

Choosing Remove Constraints...the result...

Revit removes the length constraint and honors the alignment of the windows.

Similarly, equality constraints lose to length constraints. Do both of these on elements and Revit will offer the same warning. When you choose to remove constraints Revit will try to keep the length constraint and remove the equality constraint.

Wednesday, March 29, 2006

Mastering Autodesk Revit Building

Paul Aubin has been working hard on finishing his book about Revit Building and he is pleased to announce that it is done and nearly shipping. You can check Amazon for availability and check his site for more information.

Well done! Another Revit resource for all the new Revit users to use!

Hey...while I'm plugging a new book don't forget that Christopher Lay Fox and Jim Balding's book has been updated. Check it at Amazon.

Tuesday, March 28, 2006

Do you Revit in French?

Then another Revit blog may come in handy? Daniel Hurtubise has started a blog and he's posting in French. He's the cadd manager for Lemay Michaud Architecture and they have offices in Quebec and Poland. He's also a frequent contributor to the Revit forums at AUGI.

I can even make out the basic content of his article's even though I do not know the language. I guess enough Revitese is present to give me a clue? Check out his BLOG when you get a chance.

Once Upon a Reference Plane

[Updated to reflect current version options - 09/20/08]

Once upon a time King Solid and his Voids prepared to journey across their great land, alas they weren't sure which vessel to use, Reference Planes or Reference Lines...abrupt end to segway...

Reference Planes have slightly different roles when you are making a family versus working in a project.

In a project they act as a construction line, a guide to layout your design. They do not have a real endpoint even though there is a grip at each end to adjust how much of the Reference Plane we see. Since there is no real endpoint you can’t snap to the midpoint of a Reference Plane. Just to confuse you though, you can snap to the endpoint of a Reference Plane, yes, the endpoint that doesn’t really exist.

They have the same 3D/2D toggle that Grids and Levels have. This gives you global or view specific control over how much Reference Plane you want to see. When you don’t want to see any of it you can choose the Right Click option Hide in View > Elements (or Category if you want to hide them all).

Change your mind later and want it back, click on the little light bulb on the View Control Shortcut Bar to turn on the Reveal Hidden Elements tool.

Find the reference plane or planes you want to restore, select them and then click the Unhide Element button on the options bar or via Right Click.

Related to their role in families they can also provide a work plane for elements like roofs created with Roof by Extrusion, model lines, In-Place Families and Massing. To act as a workplane they must be named first, just edit its properties and supply a name.

In the Family Editor their role is similar though with some additional responsibilities. Each Reference Plane has a parameter called IsReference. This is crucial to use properly so families behave themselves when exchanged for other families of the same category. It is also the key to making adjustable families that can be grip edited to change sizes when combined with instance parameters.

The 3D/2D behavior of Reference Planes in a project does not extend to the family editor environment (not entirely true since Revit 2010). They are invisible in a project except for how the IsReference parameter permits them to be used.

In both a project and the Family Editor the orientation of a Reference Plane determines which direction is positive. Huh? When you create a solid or void on a named Reference Plane the direction or depth of that solid/void that is a positive value is derived by the orientation of the Reference Plane. Still confused? Okay here’s an image.

When you sketch a Reference Plane the first point you place is the tail, the second the Head. When you name the Reference Plane the head is where the name appears. In the image above you should notice that the positive direction is to the left of the Head when the tail is “beneath” the Head. Try turning the image so the Head is at the top and the tail beneath (just try tipping your head to the right instead of trying to turn your monitor).

The positive direction is always to the left of the head when oriented this way. Or is it? The existing Reference Planes in the stock Revit family templates behave exactly opposite. If you sketch your own they will abide by the rule above. Just these existing Reference Planes do not. I do not know why…hmmm.

When you drag the grip endpoint of a Reference Plane across the other end, to flip the orientation, you’ll find that Revit will flip any objects that were using the Reference Plane.

Reference Lines
Since a Reference Plane has no real endpoint it can’t be relied upon to define angular constraints. In some cases you’ll get reliable behavior and you’ll flex a family and suddenly the angle seems to lose its bearings. Reference Lines were created to resolve this issue. So what about them, Reference Lines, that is?

Well first of all, Reference Lines have real endpoints. This is important to maintain angular constraints. They have no counter part in the project environment except that they look and behave more like model lines (Revit 2010 has changed this a bit, update to follow) family editor. Despite this similarity they are a separate annotation category and the option to Hide Ref/work Planes when printing, within the family editor, controls their visibility as well as Reference Planes.

They are associated with the workplane they were created on. This means you can add Reference Lines to the workplanes of other Reference Lines and/or Reference Planes allowing you to create complex nested relationships.

Straight Reference Lines contain four work planes, one flat/parallel to the view/workplane the line is sketched in and the second vertical, perpendicular to the first, as pictured here.

You’ll have to use the TAB key to select the second plane. These workplanes cannot be named nor can the Reference Line itself, you can only select them by using the Pick a Plane option when setting a work plane.

Arc Reference Lines do not define any workplanes.

Reference Lines only have three IsReference options, Not a Reference, Weak and Strong. Accordingly, they will behave the same as Reference Planes when loaded into a project. In the family editor, Reference Lines are also visible in a 3D view where Reference Planes are not.

When you need to define workplanes that will flex according to angular constraints reliably, think Reference Lines. Possible uses for Reference Lines might be parametric trusses, 3D panel door swings or the “Pixar” articulated lamp example David Conant has posted at AUGI.

When you place nested components or create solids/voids using the workplane of a Reference Line they will maintain their position according to their relationship to the Reference Line.

And upon a Reference Plane/Line they lived happily ever after!

Monday, March 27, 2006

Where did he go?

Who? You! Me? Yeah you!

I'm sorry I've let the blog slide for so long this month. I could tell you how busy I've been, but that would seem like whining and I'm not because busy is great! Just sometimes busy means too busy to find enough to write another article. Fortunately other bloggers are keeping busy providing useful insight into Revit. So I may have been quiet but the information keeps flowing and I thank each of the others for that.

So what is new? Revit Building 9, Revit Structure 3 and Revit Systems 1!! That's what!! The release of these new versions of Revit draws near!

I attended three Revit user groups last week and saw presentations of each courtesy of Autodesk, LA CAD, South Coast Revit User Group, Inland Empire Revit User Group and LA Revit User Group.

Amy Fietkau, an application specialist for Autodesk (also "Ask Amy"), presented the beta software and we were released from the quiet period on Thursday night at the last show. She did a fine job of showing/explaining and fielding the myriad questions thrown her way. I hope she got some rest over the weekend because not only did she do a whirlwind tour of three user groups but she also visited a bunch of area firms in between with Chuck Keeley, Southern California Autodesk Sales Representative. Almost rock stars! Just missing the tour bus and the deli trays, actually there was just the bus then. Next time if you want a bus, let me know, I know some places you can contact from my old roadie days...

The LA presentation drew the largest crowd of over 100 folks and John A. Martin & Associates provided the venue. The majority of those in attendance at each meeting were architects and primarily interested in Revit Building 9 with a few engineers in attendance in LA.

So what can I say about the new software? Too much to mention in this brief post unfortunately.

I can say the new room features are very nice. The ability of colums, in-place walls and curtain systems to be room bounding is great! Keynoting will be a very welcome addition for many. The very significant increase in control over the visibility of linked files is huge! Additional copy/monitor control for walls and slabs and additional API changes allowing creating views and sheets will be an asset too. Probably the biggest feature is the way we can save views from one project and use them in another. If you save a sheet view it will bring along all the related views on the sheet as well!!!

One of my favorites that Revit Building inherits from Revit Structure is the improved options for sloping steel making it much simpler to slope steel under a warping roof surface.

Revit Systems looks great! One feature, the creation of air flow analysis through a third party application like Trane Trace and the resulting color fill plan in Revit, drew the comment that it could save WEEKS in the engineering process alone.

We do need to keep in mind that it is release one software. As such the focus has been on providing engineering data and not on completing the documentation of the design. Therefore, Revit Systems will be sold only as a bundle with Autodesk Building Systems until the documentation features are filled out more completely. The intended workflow is to only use Revit Systems if you are working with an architect using Revit Building. There is no intended workflow for using it with an architect using AutoCAD or other 2d/3d cad software at this time. I surmise that it is possible, just not intended...

All for now!!

Thursday, March 02, 2006

Department of Subtle - Chain Option

Sketching walls (or lines) every so often you want to sketch several sequentially and that is where the Chain option comes in.

No surprises there really, expected actually. The thing I find to be subtle and elegant is that when I sketch a wall that touches another the command ends there. It doesn't try to continue sketching another segment from that intersection. It just makes sense to me. It is one of those things that you don't necessarily notice because it just happens and you can take it for granted.

Subtle and elegant, NICE!

Wednesday, March 01, 2006

Active Workset

Anyone who spends significant time in a project using Worksharing has put things in the wrong workset...maybe once at least? There really isn't a fool proof way to make sure that you always put them in the right place either, except somehow training yourself to always check it. I'm trying...really...

So I had the pleasure of spending a couple hours with a pair of Revit afficionados in Minneapolis tonight. The first, Tom Dorner with Jafvert Mueller Architects and the proud owner of the blog Reviteer. The second, Rolly Stevens with Elness Swenson Graham Architects who I am embarrassed to say does not have a blog...YET! No worries Rolly...there are enough for now? I also met Dick Bates with Ryan Construction the night before. My thanks to Tom, Rolly and Dick for the chance to hang out with them while in town!

Where am I going with this? Oh, yes...while chatting we ended up talking about Revit believe it or not and I was reminded of this idea I had see...what if?

Let's say a scope box could be assigned a workset and any model object that landed inside could automatically belong to that workset? Well...after a couple of Newcastle's it seemed coherant. I'm sure something better is possible. This issue deserves some devoted thought since it remains one little chink in the armor of what is a really great feature of Revit.

Again I'm one week too early to catch a local Revit user's meeting!!! Drat!