Building Design

Autodesk Revit 7

1 Nov, 2004 By: AIA ,H. Edward Goldberg

Building modeling software adds long-awaited API.


Less than one year after the last major release, Autodesk announced Revit 7, the latest update to its parametric building modeler. I reviewed a prerelease version of this program, as well as the Revit-based structural engineering and MEP engineering applications that are currently in beta release. I must admit that I am impressed.



In this new version, Revit retains its familiar graphic interface and methodology. Autodesk has refined existing features and added new ones. I often wonder how they figure out how to create features that I never realized I needed and then make them so easy to use that they become indispensable.

In the Revit parametric building model, every drawing sheet, 2D and 3D view, and schedule is a direct presentation of information from the same underlying building database (figure 1). Effectively, all the information about the model resides in the same place and any change to any part of the database is reflected throughout the collective database. The views of the building model generate the standard construction documents. As users work in any views, Revit collects information about the building project and coordinates it across all other representations of the project. Revit 7 automatically coordinates changes made anywhere in model views or drawing sheets, schedules, sections, plans, and renderings.

 Figure 1. In the Revit parametric building model, every drawing sheet, 2D and 3D view, and schedule presents information from the underlying building database.
Figure 1. In the Revit parametric building model, every drawing sheet, 2D and 3D view, and schedule presents information from the underlying building database.

Revit 7 supports all phases of the building process, preserving information from beginning to end. The same model that's rendered in design can also be used, for example, for energy analysis and other applications. Revit 7 implements a long-awaited API (application programming interface) that should facilitate direct links between the architectural software and other applications such as the structural engineering and MEP programs that Autodesk has in the works .

With so many new and innovative features, it's difficult to list all of them in the space available. I'll cover the most important features for architects.

Figure 2. Using Revit Building Maker, users develop conceptual models and can create an associated shell. As the design progresses, the conceptual model and the building model are in sync.
Figure 2. Using Revit Building Maker, users develop conceptual models and can create an associated shell. As the design progresses, the conceptual model and the building model are in sync.

At the Schematic Stage

More architects are designing in the virtual environment. Virtual massing studies often solve visual as well structural problems. By using rapid prototyping techniques, users can generate plastic 3D models of their concepts.

Building Maker is Revit 7's new modeling and design environment that integrates with the building model (figure 2). Revit Building Maker lets users develop conceptual models and apply building model components. The software captures design intent and details at conceptualization. This is a great improvement from v6.1's massing model system that is used to create the entire building shell automatically. In Building Maker, users select massing or generic model faces to create building components. Users can create walls from any vertical face, curtain wall systems from any face, roofs from sloping and horizontal faces, and floors from floor area faces.

Autodesk Revit 7
Autodesk Revit 7

Use the Right Tools

Revit 7 now features stacked walls that describe wall thickness changes at different building heights (figure 3). Stacked walls can be composed of walls that are designed for different uses and can be scheduled for easy quantity takeoffs.

The software includes profile-based mullion types, wall panels support, and improvements to curtain gridlines. The new Walls toolbar helps users draw walls, convert linework to walls, and convert faces to walls.

New tools for creating site plans include a Site Subregion tool for making parking lots and roads that stay associated with the topography. Revit's groups the best way to create repeating units, such as hotel rooms, offices, and apartment layouts. Groups have been substantially improved to better support repeating units.

Autodesk Extends BIM with Revit-based Structural and MEP engineering programs
Autodesk Extends BIM with Revit-based Structural and MEP engineering programs

Revise the Revisions

Revit 7 supports revision numbering by project or sheet. Revision tracking is easier with three new tools. The first is Revision Clouds that can be tagged to expose information such as revision numbers. Second is a new global table that lists all revisions in the current project. Users can create new revisions or merge with existing ones. For each revision, users enter information such as when the revision was made, to whom the revision was issued, and a brief description. In addition, they can toggle visibility of all revision clouds of a specific revision number and designate revisions as having been issued. Once a revision is marked as issued, revision tags can't be modified in any way, other than visible or invisible. The third component of revision tracking is the revision schedule. The schedules automatically record all the information from the revision clouds that appear on the sheet. To ensure accuracy, the schedules can't be modified.

Legends

Legend views provide a way to create needed drawings, such as typical wall types that architects normally produce in their construction document sets. The new legend view lets users create symbol legends without adding elements to a project with any model, annotation, and system family element displayed. A single legend can be placed on many sheets. Fully associated legends ensure that the graphics symbol displays stay coordinated.

Move Data Around

Revit imports, exports, and links data using the DWG format. Its native support for DWG and DXF formats enables smooth data exchange among team members. In Revit 7, identical instances in a view, such as furniture components, are written as instances of the same block during DWG and DXF exports.
Figure 3. Stacked wall types describe cases where wall thickness changes at different building heights. They can be composed of walls designed for different uses.
Figure 3. Stacked wall types describe cases where wall thickness changes at different building heights. They can be composed of walls designed for different uses.

The Output to MicroStation DGN feature ensures smooth coordination between Revit 7 and MicroStation. Identical instances in a Revit view are written as instances of the same cell definition in DGN exports. Revit 7 imports 3D solid geometry, except for general NURBS (nonuniform rational b-spline) surfaces, increasing collaboration opportunities with users of other CAD applications.

Additional functionality includes layer query and partial explode of imported DWG files as well as the ability to orient imported DWG files to Revit views.

In addition to the AccuRender-based rendering and animation capabilities provided in Revit, users can also visualize their designs with Autodesk VIZ 2005 via a plug-in, complete with Revit-assigned materials by exporting to DWG and then linking into VIZ 2005. The File Link feature of VIZ 2005 picks up changes from the model when the user reloads the link. Vectoral shadows use advanced model graphics and nonrendered views now support shadow casting. Shadows also work in 2D views such as elevations (figures 4 and 5).

Figure 4. Nonrendered views now support shadow casting, and shadows also work in 2D views such as elevations.
Figure 4. Nonrendered views now support shadow casting, and shadows also work in 2D views such as elevations.

The program can output quantity information about all the components. With skillful use of spreadsheets, users can create cost estimates.

Is BIM for Your Team?

Revit is specifically designed for BIM (building information modeling). Given this new release and what I've seen of the new structural and MEP engineering disciplines supported on Revit, I say the company is delivering on its vision. Autodesk continues to develop Architectural Desktop for architects who prefer an AutoCAD-based application for drawings. I was so impressed with Revit 7 that I'm now using it in my architectural practice alongside Architectural Desktop 2005.

If CAD users are familiar with and like the AutoCAD environment, Architectural Desktop is an excellent program. If your team is looking for a new CAD package, is just starting out with CAD, or is interested in what new technology and a purpose-built building modeling application can do, I highly recommend Revit 7.

Figure 5. Vectoral shadows can be shown without rendering a view.
Figure 5. Vectoral shadows can be shown without rendering a view.

I find Revit 7 more capable than Architectural Desktop 2005 for creating a building model. On the other hand, Architectural Desktop 2005's detailing capabilities are superior. Regardless, Revit and Architectural Desktop are both constantly being improved. For pricing and availability of Revit 7, please contact your local reseller or visit www.autodesk.com/revit.

Keep in mind that Revit 7 and other information-intensive programs need fast processors and 1- to 2GB of RAM. At minimum, Autodesk recommends users run Revit 7 on a Pentium 3 or AMD-based workstation with 512MB RAM and 250MB available disk space on Windows 2000/XP Service Pack 2.

Try the 30-day Revit 7 demo available at the Autodesk Web site. The program learning curve can be relatively short for simple structures, but users will probably need instruction for more difficult tasks. To increase skills, check out discussion groups and training CD-ROMs at www.scottonstott.com. Books are available from CDV Systems (www.cdvsystems.com), Schroff Development Corp. (www.schroff.com), and Autodesk Press (www.autodeskpress.com). See Revit City (www.revitcity.com) for helpful tips, tutorials, and components. There's also a thriving Revit community on the AUGI forums (www.augi.com).

Revit continues to gain popularity. In fact, it's the primary software application being used to develop the Freedom Tower that will sit next to the World Trade Center site and be the world's tallest structure. Highly Recommended.

H. Edward Goldberg, AIA, is a practicing licensed architect, industrial designer, and AEC industry analyst. Ed's book, Autodesk Architectural Desktop 2004: A Comprehensive Tutorial is available now (Prentice Hall, 2003, www.prenhall.com ). His new book, Autodesk Architectural Desktop 2005: A Comprehensive Tutorial, will be available soon. Reach Ed at ed.goldberg@cadalyst.com or via his personal web site at www.hegra.org.


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