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AEC

BIM and Visualization, Part 2 (1-2-3 Revit Tutorial)

31 Jul, 2007 By: AIA ,Rick Rundell

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Use a Revit building information model to experience an architect's design.

Google "Freedom Tower" and you'll get well over one hundred thousand image hits -- many of them photorealistic images of a building that hasn't been built. This is testimony to the power of today's design visualization applications and their ability to explore, validate, and convey architectural design concepts.

Last month, I began a two-part series examining how BIM improves the design visualization process and the advantages of using an existing building information model for visualization -- the most significant being avoiding the time and cost to create and coordinate redundant building models. This month, I continue the series by stepping through the process of extending the Revit building information model for visualization and then profiling two firms that use Autodesk 3ds Max to visualize, and thus experience, their Revit building designs before they're built.

Extending a Building Information Model for Advanced Visualization
Revit contains several automatic modes for visualizations, including Hidden Line and Shaded with Edges, shown in the screen capture and closeups below.

Revit also contains an internal rendering engine for quick visualizations, such as the one shown below.

For higher quality images, Revit users can transfer the building information model to 3ds Max by exporting the model to a 3D DWG format.

The 3ds Max user then imports and links the 3D DWG file. By linking the file, design changes that occur in Revit are reflected in 3ds Max.

Photorealistic renderings, such as the one shown below, can then be created with 3ds Max.

Case Study: RTKL
Founded in 1946, RTKL is a global architecture, engineering, and planning firm with more than 1,000 professionals in the United States and around the world. Several years ago, RTKL made the strategic decision to move to BIM and is currently using Revit on a variety of large-scale projects for a wide range of institutional, commercial, cultural, and governmental clients. It began to implement Revit Architecture in late 2003, followed by both Revit Structure and Revit MEP.

RTKL's Dallas office has used 3ds Max for visualization for many years, implementing it several years before using Revit. Colin Davis, a lead 3D artist in the company's internal visualization studio recalls, "We would start the visualization process by using AutoCAD to create a 3D model of the architect's design, usually based on their 2D drawings. When the architects began using Revit, we eliminated that whole step and began using 3D DWGs exported from Revit." Now, they just import those files into 3ds Max and get to work producing the visualization itself.

"Because we don't have to model the building anymore, we use the extra time to improve the realism of the visualization," explains Davis. "We can spend the time fine-tuning the materials, the textures, the lighting, and adding extra details like furniture and accessories, surrounding structures, and landscape -- even animated 3D people and cars."

In addition, RTKL's architects are making good use of the visualization capabilities within Revit for quick renderings and regular hidden-line views and color sections -- particularly in the early stages of design, leaving the visualization studio to focus on the high-quality presentation material needed for reviews, approvals, and marketing. In fact, Davis feels that one of the major benefits of using the Revit building model in 3ds Max is that their designers are spending more time fleshing out their ideas in the building information model. "The time saved by not having to create, develop, or coordinate the model means we can produce higher quality visualizations - ones that accurately portray the architect's design."

Case Study: Ayers/Saint/Gross
Ayers/Saint/Gross (ASG) specializes in design and planning for nonprofit institutions, with a specific focus on higher education. With offices in Baltimore, Phoenix, and Washington, D.C., ASG's 125-member staff includes architects, planners, urban designers, landscape architects, interior designers, graphic designers, and 3D visualization experts.

ASG began using 3ds Max in 2003 when the company formed its own in-house imaging studio by acquiring an architectural visualization company already using 3ds Max for their visualizations. Initially, this new group also used 3ds Max to recreate the architect's design (typically based on 2D AutoCAD drawings). As the 3D DWG format emerged as a high-fidelity vehicle to transfer model data, this in-house imaging studio purchased Revit for its modeling capabilities and began to use it, rather than 3ds Max, to build visualization models.

In parallel, the firm also began investigating BIM and BIM solutions because it was eager to use a common 3D building model throughout the design process -- to visualize and communicate building design solutions from early conception through construction administration without redundant modeling efforts. The success of Revit within the imaging studio influenced the firm's decision to pilot the software for its architectural design needs as well and the company launched a pilot project in early 2004. It was so successful that within a year the firm decided that all new projects would start in Revit.

"The architects now send us 3D DWG files exported from their Revit building information models, which we can import and link directly into 3ds Max," explains Brian Russell, an integrated practice manager in ASG's visual imaging studio. "Visualization technology has dramatically improved in the last few years, reducing rendering times and increasing the quality of the output. Now, we can save even more time by not recreating the architectural model." This has led to more visualizations (and higher quality ones) throughout the design process. For example, it used to produce only one or two renderings for a project, typically after the building design was complete, just prior to construction. Now for most projects, it produces at least one per design phase and often many more.

In addition, visualizations were typically reserved for marketing purposes or for milestone events such as client presentations and approval processes. But now they're also used for design investigations. "An architect will sit with me and we'll try on different finishes or change the lighting scheme," explains Russell. "We perform sun studies or lighting simulations, create renderings or animations -- whatever the design team needs."

3ds Max has also helped ASG to increase the amount and quality of animations it produces, using its advanced visualization capabilities such as character and crowd animation to study how a building information model will function with people -- humanizing the design for presentation purposes. It also uses Revit and 3ds Max to model and aggregate surrounding landscape or structures, another critical ingredient for convincing visualizations. In fact, using a combination of Revit, AutoCAD, 3ds Max, and Google SketchUp, they recently modeled a good chunk of downtown Baltimore to produce a 30-minute animation sequence for a combination of waterfront redevelopment projects. "We used Revit to model the proposed construction, as well as several nearby (existing) buildings for optimal building detail -- so when we dropped a camera in at street level, the results were very realistic," Russell explains. Initially, the assignment was just to produce a series of still images, but the real estate developer was so impressed he commissioned the animation to sell the project.

Efficient, Accurate Communication of Building Designs
Design visualizations are an exceptional medium to accurately visualize, thoroughly study, and effectively communicate building designs. BIM is making their creation even more efficient.

The ease and fidelity of transferring the Revit building information model to 3ds Max significantly reduces the time and cost to produce the visualization. Linking the Revit building information model to 3ds Max further minimizes the time required to coordinate the architectural design and the visualization. But, ultimately, it is the detail embodied in the building information model that ensures that the resulting visualization is a true reflection of the architect's vision.