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AECbytes Product Review (June 26, 2007)

Revit Architecture 2008

Product Summary

Revit Architecture 2008 is the renamed new version of Autodesk's BIM application for architectural design that integrates elements, views, and annotations into a single, coordinated building information model. It was formerly known as Autodesk Revit Building.

Pros: Ease of use remains unmatched, despite the continued addition of features enhancing the power and sophistication of the application; critical improvements in groups and linked files, and the ability to split views, which make it easier to model and document large projects; several display enhancements that allow views to be customized as required; revamped color fill capabilities for creating color-coded plans; improved export of materials to 3ds Max; API expanded to provide access to more Revit functionality for developing supporting tools; tutorials have been expanded to cover most aspects of the application.

Cons: The room element introduced in the last release is still problematic and not fully developed; some illegal operations such as overlapping elements continue to be allowed, making it difficult to guarantee model integrity; limited capabilities for conceptual modeling or the detailed modeling of complex forms; built-in rendering capabilities not on par with those in other modeling and BIM application; only marginal improvements made to the main documentation; tutorials are good but need to be separately downloaded and installed.

Price: Suggested retail price is $5295 for Revit Architecture and $5695 for the AutoCAD Revit Architecture Suite.

In last month's newsletter on the AIA 2007 National Convention and Expo, I provided a brief overview of the new release of Revit Architecture (formerly known as Revit Building), which was demonstrated by Autodesk at the show. Going by the officially released seat count, the adoption of the Revit platform has doubled in the past year, which doesn't come as much of a surprise, given the growing interest in BIM among all the players and stakeholders in the AEC industry. This, in turn, allows Autodesk to continue to invest heavily in the development of all the Revit-based disciplinary BIM solutions. Let's look at the improvements that this annual development cycle has engineered for the architectural users of Revit in the 2008 release.

To compare Revit Architecture 2008 with previous releases, please see my reviews of Revit Building 9, Revit Building 8/8.1, and of Revit 7 and Revit 6 from the days when Revit was still a single application rather than a platform of multiple products.

Improvements in Usability and Workflow

Of the three discipline-specific BIM solutions that are now available on the Revit platform, Revit Architecture is the one with the longest development history, as Revit started off being an architectural design tool all the way back in April 2000, when the first version of its parametric building modeler was released. With over seven years of development, it does, by now, have a fairly complete feature set of modeling tools for architectural design, allowing the development efforts to focus on other aspects of the application such as improved usability, robustness, and workflow. These improvements span across several tools and tasks of the application in Revit Architecture 2008.

Let's start by looking at the Groups feature, which allows you to combine elements into a larger entity and is particularly useful for modeling repeating units in building types such as apartments, hotels, offices, and so on. A change made to one instance of the group is automatically updated in all the other instances. This kind of group editing is made easier in Revit Architecture 2008 with a Group Edit mode where the rest of the model, except the selected group, is grayed out, as shown in Figure 1-a. Also, all the tools in the Design Bar now continue to remain active in this mode, making it easy to add additional elements to the group. In addition to being able to remove elements from the group in the Group Edit mode, as shown in Figure 1-a, it is now also possible to exclude an element only from a specific instance of a group without affecting the other instances. This is done by using the Tab key to highlight and then select a group element in the normal rather than Group Edit mode, and then simply clicking on a icon to exclude it from that group instance, as shown in Figure 1-b. The ease with which individual elements can be excluded from specific instances of groups means that you can get by with creating fewer groups and customize the instances with minor variations as needed. Excluded elements can be restored to their group instances at any time.

Figure 1. (a) Editing a group in the Group Edit mode. (b) Selecting an element to exclude it only from that group instance.

Other Group-related enhancements include the ability to save a group as a Revit project file (RVT) if you are working in a project, or as a Revit family file (RFA) if you are working in the Family Editor. The corresponding options to load an RVT file into a project or an RFA file into the Family Editor as a group are also available. This lets groups be edited independently of the project or family in which they are loaded. Groups are no longer saved in the Revit Group file format (RVG); however, existing RVG files can still be loaded into projects and families for use as groups. A closer relationship between groups and linking has been established by the ability to convert groups to linked Revit models and vice versa. This is useful in the scenario where a linked model needs to be edited against the main model to take care of joins, overlaps, inserts, and so on. The linked model can be converted to a group and edited in the context of the main model, and then converted back into a link. This feature is also useful for interference checking or conflict detection between linked models.

In addition to the ability to convert a linked model to a group to edit it within the context of the project—a process termed as "binding" the link—Revit Architecture 2008 incorporates several other improvements in linked files to increase the usability of the application for large projects. Linked files are now organized and displayed in the Project Browser, and nested links can be seen under the links they belong to, allowing the project team to get a clear idea of the project structure. Links can be opened and edited from the Project Browser, and a context menu provides access to all the linking related tasks (see Figure 2). Nested links can be made visible or hidden in the host model. An element from a linked model can be highlighted with the Tab key, copied to the clipboard, and then pasted into the host model. Elements in the linked model can also be used as references for dimensions and aligning in the host model. It is even possible to create constraints between elements in the host model and elements in a linked model—for example, aligning a wall in the host with a wall in a linked model. While scheduling has worked across linked files in Revit for a while now, what is new in this release is the ability to schedule elements by link, as shown in Figure 2. Other enhancements include the ability to apply the host model color scheme to rooms and areas in a linked model, and show or hide areas and area boundaries. Overall, the improvements in linking make it easier to divide up a large project into multiple linked files, as the individual models can now interact more closely and behave like a more cohesive whole.

Figure 2. A site model with two linked files, as shown in the Project Browser. One of the linked files has two copies placed on the site, named Townhouse A and Townhouse B. The combined door schedule is shown, showing the linked file to which each door belongs.

Other new feature especially targeted towards large projects is the ability to split up a large floor plan, section, or elevation view into multiple smaller segments to place them on sheets at a readable scale. This is done by duplicating a view as a dependent view and then cropping the view as desired. Any number of dependent views can be created for a view. Figure 3 shows an example of a large floor plan which has been split into two views for placing on two different sheets. As you can see, this also makes it easier to illustrate the inclined portion of the building—the dependent view containing that portion (the West wing shown in the last image) has been rotated so that it is displayed horizontally. This can make dimensions and annotations easier and more readable. Dependent views are displayed in the Project Browser under the primary view. You can insert matchlines—shown in Figure 3 by the dashed blue line—to indicate where the view is split, as well as view references in the primary view to link to the dependent views. All the dependent views remain synchronous with the primary view and other dependent views, so that if any changes are made in one view, they are automatically reflected in all views. In addition to the main crop region which determines where the view is split, an annotation crop region has also been introduced which can be adjusted in each view to control which annotation elements are cropped and which are retained.

Figure 3. A large floor plan, shown in the top image, that has been split into two dependent views for placement on two separate sheets, as shown in the middle and bottom images.

Display Enhancements

Revit Architecture 2008 features a number of enhancements that provide the user with a lot more control over how a view is displayed. Previous versions of Revit included options to hide or isolate elements or categories, which were useful for seeing or editing only a few elements of a certain category in a view. These options were only temporary, and the element visibility reverted back to its original state once the project was closed and re-opened. The temporary hide/isolate also did not affect printing. Thus, this feature was really designed to be a modeling aid rather than a means for customizing the display of a view. In Revit Architecture 2008, the hide/isolate feature has been expanded so that the changes are permanent—in other words, they persist after the project is closed and also affect the printed output. As shown in Figure 4-a, you can select one or more elements in a view and then choose to hide all those elements or the entire categories to which they belong by selecting the corresponding option from the contextual menu. This change will now be permanent for that view unless the elements and categories are returned to their unhidden state. A new Reveal Hidden Elements mode has been introduced to facilitate this task—it allows users to see all the hidden elements in a view and selectively choose elements or categories to return to visibility, as shown in Figure 4-b.

Figure 4. (a) Selecting an entourage element and choosing to hide the entire category to which it belongs in the current view. (b) Seeing the hidden elements in the Reveal Hidden Elements mode, from where they can be restored to visibility if needed.

Another enhancement that allows greater control over how a view is displayed is the ability to apply graphic overrides to individual elements to display them differently from the graphic settings associated with their categories. Figure 5-a shows how this feature has been applied to display the different floor slabs in a plan view in different patterns. The same dialog can also be used to turn off the visibility of the element, or display it in a half-tone (where the color blends half-way with the background color) or transparent display (where only the edges of the element are displayed but not the surfaces). The contextual menu containing the graphic overrides by element option also has the options to override graphics by element category or by user-defined filters. These commands take you to the same Visibility/Graphics Overrides dialog for the view that was available in previous versions, except that they take you directly to the selected category or filter and work as convenient shortcuts. The Visibility/Graphics Overrides dialog has been expanded to include additional display options, as shown in Figure 5-b, including separate Lines and Patterns options for Projections/Surfaces as opposed to Cuts. This now allows, for example, walls in a 3D view to be displayed in a color other than the one associated with its material in the Object Styles dialog, which are applied at the level of the entire project. This is shown in Figure 5-c, where the walls are displayed in the Override options specified in Figure 5-b.

Figure 5. (a) Using graphic overrides to display floor slabs in different colors and patterns only in the current view. (b) The enhanced display options for elements in the Visibility/Graphics Overrides dialog, with an override selected for the Walls category in a 3D view. (c) The 3D view showing the walls in the specified override color.

In addition to the general display enhancements described above, Revit Architecture 2008 also includes a number of enhancements specifically related to color fills for rooms and areas. Previously, color fills and color legends were combined in the Color Fill command. Also, the legend was an aggregated one showing the colors from all the views rather than only the colors seen in a specific view. All of these limitations have been addressed in this release. To start with, you can now create and manage color schemes independently of applying a color fill to a view. Figure 6-a shows the new Edit Color Scheme dialog, where multiple color schemes for Rooms have been defined based on different properties. The color scheme is now a property of a view, which means that different schemes can be applied to different plan views, allowing you to very easily create different displays for illustrating different aspects of the plan such as areas, occupancy, department, and so on. Other options include the ability to control whether the color fill appears in the background (with furniture and equipment on top of the fill) or in the foreground, and whether it applies to rooms and areas from linked files. In previous versions, deleting the color legend in a view also deleted the color fills, as the two were tightly integrated. Now, the color scheme is part of the view, which means that it can be displayed even without placing a legend. The legend element itself has been improved by the ability to display only view-specific values, so that the legend on a plan only shows the color fills appearing on that plan rather than on all the plan views, as shown in Figure 6-b. Other legend-related enhancements include the ability to resize it, resize the swatches (the color boxes that appear in the legend) and change their graphic appearance, and modify the order of items in the legend.

Figure 6. (a) The new Edit Color Scheme dialog, showing three different types of legends defined for Rooms. (b) Applying the Name legend shown in the dialog to the East and West split views from the project shown in Figure 3. The legend has been set to display only view-specific values.

Other Improvements

On the modeling front, Revit Architecture 2008 includes a new shape editing feature for roofs and floor slabs that allows you to subdivide its surface into parts that can slope independently, making it much easier to create, for example, sloping roofs in any desired configuration. It works by providing four additional slab modification tools that get activated when any flat, horizontal slab with straight edges is selected. You can create points on the surface at a specified elevation, which automatically subdivides its surface, or directly draw the lines to subdivide the surface and then modify its shape by manipulating the individual edges or points (see Figure 7). An additional tool allows you to select the supports of the slab such as linear beams and walls to create new split edges on the top face. A Reset Shape option can be used to quickly reset the slab to its original shape, allowing you to experiment freely with the slab editing tools. If the model is exported to Revit Structure, it is important to note, from a structural analysis perspective, that this kind of editing does not affect the shape of the analytical model which continues to be based on the original top face of the slab. Other modeling enhancements include the ability to cut openings on planar faces of structural beams, braces, or structural columns using the Opening by Face command. Rectangular openings can include fillets to avoid sharp corners on the opening. Wall sweeps that are used to add cornices to walls can now be independently scheduled using the Wall Sweeps category in the New Schedule dialog, allowing better estimates for the walls to be generated from the model.

Figure 7. Using the new slab modification tools to quickly create a complex roof configuration from a flat slab.

Some enhancements targeted towards drawing production include smarter dimension arrows that recognize when a dimension segment is too small to accommodate the arrows on the interior of the dimension line and automatically flip to the exterior of the dimension line. Spot dimensions that are used to mark spot elevations and spot coordinates can now be placed on non-horizontal surfaces and non-planar edges. Also, the value of the spot elevation or spot coordinate appears in the drawing area in ghosted form before it is placed, which is helpful. You can have different leaders for different spot dimensions, even if they are of the same type. There is now a dedicated masking tool for controlling which elements will obscure other elements in a view. You can create a masking region directly in a project to obscure desired elements, or in the Family Editor while creating a 2D family such as an annotation, detail, or titleblock. You can also create a masking region in the Family Editor while creating a 3D family. Masking regions created in a family allow its elements to mask the model and other detail elements when it is loaded into a project.

Revit Architecture 2008 continues to improve upon its interoperability with other applications. When you export a 3D view for use with 3ds Max or VIZ, the section box used to limit the exported content has been enhanced to make it easier to specify its size and location more accurately. An element that has different materials applied to interior and exterior surfaces in Revit retains the materials when exported using ACIS solids, as opposed to showing only one material for the entire solid, as in previous releases. Also, exported materials now use the more readable RevitMaterial Names. Revit Architecture 2008 can export to the AutoCAD 2007 DWG format, and it achieved IFC 2x3 certification last month. On the DWF front, the default zoom setting when publishing 2D DWF is now Fit To Page, which avoids getting a cropped portion of the 2D view in the DWF file. A link to Google Earth will soon be available to subscription members, allowing Revit Architecture to finally catch up with other CAD and BIM applications in allowing users to bring site information from Google Earth into Revit and export a Revit model back into Google Earth with the correct geo-referencing information, so that it can be viewed on the actual site. Revit's API (Application Programming Interface) continues to be expanded to make it easier for third-party vendors to develop supporting applications, such as those described in the recent article, Supporting Technologies for BIM Exhibited at AIA 2007.

And finally, some improvements have been made in the documentation accompanying the application, the quality of which I have criticized in previous reviews. There is now a New Features Workshop, similar to the one that comes with AutoCAD, which provides an overview of many of the new features of the application. While it is not very comprehensive and does not show you how to actually work with any of the new features, I found it a useful way to get acquainted with the new features before moving on to the rest of the documentation for further information. The detailed documentation itself has been marginally improved with the addition of some more illustrations to counter my earlier criticism of having an overabundance of text that was insufficiently illustrated. In contrast, the tutorials have been better developed, with well illustrated exercises demonstrating most of the functionality of the application, accompanied by the datasets used in the exercises. The only downside is that the tutorials are not installed with the application, and are not even included on the application CD; they have to be downloaded from the Autodesk website and require multiple downloads to get all of them.

Analysis and Conclusions

Revit Architecture 2008 continues to build upon its solid foundation as an easy-to-use, powerful, and comprehensive BIM application for architectural design, with a steady pace of development that adds a set of enhancements and improvements in every release targeted towards different aspects of the application. The main focus in this release was to make it easier to work with groups and large projects, with improvements in the editing of groups, working with linked files, and the ability to split large plan, section, and elevation views into smaller dependent views that can then be placed on sheets at a more readable scale. The other main focus was on enhancing the display options so that different views can be customized to look exactly as desired, with the ability to permanently hide some elements in a view and apply graphic overrides to other elements to display them differently from the graphic settings associated with their categories. The substantial improvements in color fills should make it much easier to create color-coded plans for presentation drawings as well as space planning and facilities management tasks.

The number of improvements to modeling, detailing, and annotation tasks are limited in this release, but users will still appreciate the benefits of slab editing, scheduling wall sweeps, automatic positioning of dimension arrows for readability, the ghosting of spot dimensions before placement, and being able to control which element obscures another element through masking. The interoperability with Google Earth is long overdue, and with most Revit users relying on 3ds Max or VIZ to generate high-quality photorealistic renderings, the improvements in exporting the Revit materials will be extremely useful. The considerable expansion of the API, while invisible to the average user, will serve to support the growing universe of supporting applications that integrate with Revit to expand the power and scope of its BIM capability.

On the flip side, this release of Revit Architecture does not address many of the problems I had pointed out in my review of the last release. The Room element that was introduced in Revit Building 9 still does not have full automatic detection of its vertical footprint with roofs and ceilings, making it difficult to represent all but the simplest building sections with rooms correctly. Despite having a large number of built-in constraints that regulate the modeling to prevent inaccuracies and errors, Revit continues to allow illegal operations such as overlapping doors, columns, windows, etc., which require interference checking to be used to detect them. Thus, while Revit may be "smart," it is not yet smart enough to guarantee full model integrity and a conflict-free model, even within a single disciplinary solution like Revit Architecture. Modeling non-regular building forms continues to be a challenge in Revit and its conceptual modeling capabilities are not good enough to avoid the need for applications like SketchUp and form.Z. The improvements that have been made to the documentation in this release are quite marginal; I still found it a poor resource for learning to use the application, in contrast to the tutorials which were a lot more useful.

Hopefully, some of these limitations can be addressed in future releases of the application. Also, I hope that Autodesk does not stay content with simply continuing to develop Revit with an incremental set of improvements in every release, but can also take a step back and explore the potential for some dramatically new ways of modeling and working. A case in point is the Groups feature. Even though it is an efficient way of modeling repeating units in a project, it does not actually reduce the file size since the geometry is being duplicated for each instance of the group. There should be a smarter way to represent repeating units so that the file size is reduced—with some kind of reference capability that still works with Revit's centralized data model rather than the distributed nature of Xrefs in AutoCAD. The idea of smart referencing can be applied at a much broader level as well. For example, does the geometry of a window really need to be repeatedly represented in the model each time it is inserted, increasing the size of the model? Can't it be represented just once in the model and then intelligently referenced from the other locations in which it is placed?

This was just one example of a possible change in the application that could have a radical impact on usability and performance. There could be several more, and it is important for BIM vendors like Autodesk to continue to invest some of their resources into broader R&D efforts rather than on simply improving what they have developed so far. The latter is undoubtedly important for day-to-day usability but it is the broader research and development that will lead to real innovation and ultimately shape the future of BIM.

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at

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