AEC Tech Trends #144

18 May, 2005 By: Michael Dakan

Cadalyst AEC Tech News

Bentley Takes Lead in Acrobat Support

MicroStation Users Can Embed Interactive 3D Designs Directly in PDF Files

I've written quite a lot recently about the new Adobe Acrobat Professional 7.0, and a couple of readers have taken me to task for not mentioning what Bentley Systems is doing with PDF support, one going so far as to accuse me of an anti-MicroStation bias. I admit I've been somewhat remiss in not covering it more.

My lack of coverage is related mostly to my personal and professional experience and history rather than a bias against MicroStation. I've lived and worked primarily in the American West, which is traditionally AutoCAD country, much like the Southeastern United States is often considered MicroStation territory. Most of my architectural and computer consulting practice involves CAD software other than MicroStation. I don't hear much demand for information about it in my daily work, and therefore I tend not to cover it in my writing as much as other CAD software. But I have been aware of the work that Bentley has invested in Acrobat technology as well as the complete functionality of MicroStation V8 to address the CAD needs of many users throughout the world.

Integrated PDF Support
Bentley has worked directly with Adobe engineers to develop the ability to directly write PDF files from within MicroStation V8, and in fact is a leader in supporting Acrobat's 3D capabilities. The latest version of MicroStation V8 2004 Edition writes and exports U3D models to an interactive Acrobat page or separate PDF file. The exported model file can encapsulate the model geometry, materials, lighting and texture maps within the PDF. Either method requires that you have a licensed copy of Adobe Acrobat Professional 7.0 to insert the U3D content into a final PDF.

U3D is a universal 3D model file format that Adobe has adopted for use with Acrobat, and it hasn't yet gained much direct support from CAD developers. Bentley is a notable exception. Most CAD developers will probably rely on third-party file translators and programming libraries that must be developed before we can expect to see much widespread support for U3D. Autodesk probably shouldn't be expected to provide much direct support for Acrobat files any time soon, because that company has its own competing compact universal file format, DWF, which provides much of the same functionality as PDF, but only for CAD files and models. One of the main reasons I prefer PDF over DWF is its ability to support any type of file that can be printed, not only CAD files.

Interactive 3D Designs
MicroStation will generate a U3D file for export that you can insert into a page using Acrobat Professional 7.0, or it will generate a separate, complete PDF file that contains the U3D content. Acrobat uses Javascript to create the required code to provide user interactivity and a control panel for navigation. MicroStation will also create a JS Javascript file with the same name as the U3D model file that provides the necessary controls the viewer can use to manipulate the model interactively. You can use MicroStation to export a wire frame model or a colored and textured rendered model and views. The file recipient, using Adobe Reader, can manipulate the model in real time. This 3D capability allows you to create an interactive presentation PDF that contains embedded models and scriptsat any point in the design cycle.

As far as I know, MicroStation V8 2004 Edition is the only CAD program to allow this one-touch creation of 3D PDF files and content. It remains to be seen whether the Adobe U3D file format will take off and become a standard that other CAD developers will support, and if we will see more support for this in other CAD programs in the future. It certainly expands the capabilities of PDF for creating design presentations that require only the free Adobe Reader 7.0 to view and manipulate interactively. Sign up now to receive a new e-mail newsletter from Cadalyst and Adobe — coming soon — that will include how-to information and tips for designers and engineers who use Adobe Acrobat Professional 7.0.

Bentley MicroStation
Adobe Acrobat Professional

Michael Dakan is an author and independent CAD and information technology consultant. E-mail him at

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