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AECbytes Product Review (October 23, 2008)

Autodesk NavisWorks 2009

Product Summary

Autodesk NavisWorks 2009 is a family of applications for 3D design publishing and project review, repackaged by Autodesk into four standalone applications after it acquired NavisWorks in 2007. The top level application, NavisWorks Manage, has all its capabilities including model aggregation, visualization, and review, 4D construction simulation, and clash detection.

Pros: Ability to open and combine files in all the popular and critical file formats including IFC; file converters available for applications such as Revit and ArchiCAD; powerful compression technology that reduces model sizes dramatically; extensive repertoire of navigation and review tools; dynamic selection sets that can be re-used across projects to make object selection and clash detection setup easier; can import schedules from applications such as Primavera P3 and Microsoft Project; free viewer application available to share the review results with a wider audience; relatively easy to learn and use.

Cons: Minor interface issues such as a surfeit of floating palettes with unpredictable docking behavior, and the lack of a 3D-2D synchronized navigation ability to quickly navigate to the exact position required in the model; no object editing capabilities; does not allow objects to be divided into parts for more accurate scheduling; no integration with other applications such as cost-estimating, project management, construction management, and facilities management.

Price: Suggested retail prices for NavisWorks Review, NavisWorks Simulate, and NavisWorks Manage are $1995, $3995, and $8995 respectively; NavisWorks Freedom is a free downloadable viewer.

I last took a detailed look at NavisWorks in Feb 2004, when the genre of 3D design publishing and review was still relatively new. Since then, the use of NavisWorks has grown to the point where it is almost ubiquitous in construction firms as well as multi-disciplinary A/E firms using BIM. For example, see the case study of GHAFARI Associates published in AECbytes a few years ago, the work done by Mortenson as described in the BIM Symposium feature, its use by HOK and Skanska in the BIM award winning Royal London Hospital project, and many more that have been featured in AECbytes. In fact, it would be fair to say that many of the benefits of BIM showcased in landmark projects such as the Denver Art Museum and the Letterman Digital Arts Center could not have been achieved without the use of NavisWorks. As Mitch Boryslawski, who worked on the BIM implementation of the Letterman Digital Arts Center, put it in his article, “NavisWorks’ unique highly compressed technology and its ability to assemble 3D large and complex models from almost any CAD application on the market today makes NavisWorks a must in the project management tool box.”

Recognizing the tremendous potential of the application, Autodesk acquired NavisWorks last year and has reworked it so that it is no longer a single application with multiple components but three separate paid stand-alone applications targeted for a variety of uses, ranging from the entry level review need to the most advanced. This review explores the new NavisWorks product line-up, followed by a detailed look at its capabilities.

The NavisWorks 2009 Product Line-up

Prior to the acquisition by Autodesk, NavisWorks was available as a modular product called JetStream. It comprised a core component called Roamer, which provided for 3D CAD file aggregation and real-time navigation of projects, and also included a comprehensive project review toolkit. The other modules were available as plug-in components into Roamer and included Publisher, which created compressed and secure review files for sharing with other team members and clients that could be viewed and navigated with Freedom, a free 3D viewer; Presenter, which allowed textures, materials, and lights to be applied to the 3D model for creating both still and animated photorealistically rendered output; TimeLiner, which allowed task schedules to be linked to 3D model data for performing 4D construction simulation; and Clash Detective, which allowed the geometry created by different 3D design applications to be reviewed together and checked against each other for interferences.

The Autodesk 2009 version of NavisWorks replaces this modular structure with three separate products: Autodesk NavisWorks Review, Autodesk NavisWorks Simulate, and Autodesk NavisWorks Manage. In addition, the free 3D viewer is now available as Autodesk NavisWorks Freedom, and it continues to remain free. Autodesk NavisWorks Review is the entry-level application, and it combines the Roamer and Publisher modules of the earlier JetStream product. Next up is Autodesk NavisWorks Simulate, which adds the Presenter and TimeLiner modules to the Roamer and Publisher modules. And finally, the addition of Clash Detective makes for the complete feature set contained in the Autodesk NavisWorks Manage product, making it the top level application of the suite.

Thus, even though there are three separate applications, they build up on each other. Let’s take a sequential look at their capabilities, starting with the model aggregation, visualization, and review tools contained in all three applications, the 4D analysis and scheduling tools available in the NavisWorks Simulate and NavisWorks Manage products, and finally, the interference checking and clash detection tools that are only available in the NavisWorks Manage product.

A quick word about the target market of NavisWorks before diving into a detailed exploration—it is intended not just for conventional building types but also for the design and construction of manufacturing and process plants/facilities. Essentially, it is useful for any project that has large 3D data sets such as commercial buildings, airports, power plants, automotive factories, and so on. It would be more difficult to justify its use on smaller scale projects such as residences. Also, it is entirely a 3D application, intended for 3D project review. If there’s no model, NavisWorks cannot be used at all. At the same time, it is intended to be used by CAD as well as casual reviewers and non-CAD users, by designers who create 3D information as well as those who need to use this information for other tasks related to the project.

Model Aggregation, Real-Time Visualization, and Review

The core model aggregation, visualization, and review capabilities in all three NavisWorks applications come from the Roamer and Publisher modules of the earlier JetStream product, as mentioned earlier, and remain essentially the same as those described in my review of NavisWorks3, so I will not describe them in detail again here. Let’s look at what has been enhanced in the application since that time, starting with the growing list of file formats that are supported. In addition to the traditional formats such as DWG, DXF, DGN, 3DS, IGES, and so on, NavisWorks 2009 also supports the direct opening of emerging important file formats such as 3D DWF, STL, and SKP (SketchUp files) as well as the open standards IFC file format. For applications whose native files it cannot directly read such as Revit and ArchiCAD, NavisWorks provides file exporters that can be used to export a native NavisWorks file format (NWC) directly from those applications. Figure 1 shows a Revit file being exported to the NavisWorks 2009 format, and subsequently opened within NavisWorks. An object in the model has been selected, and you can see in the Properties palette that many of its object properties are retained and can be viewed, including the source file it originated from.

A list of the file formats that can be directly opened in NavisWorks and the applications for which file exporters are available can be seen here. NavisWorks claims to compress individual models up to 70% of their original size, and I found this to be true: the Revit file shown in Figure 1 was close to 19 MB, while the NavisWorks NWC file exported from it was only 2.5 MB, which is a compression of over 85%.

Figure 1. Using a file exporter automatically installed by NavisWorks to convert a Revit Architecture 2009 file into the NavisWorks format, which is then opened in NavisWorks.

Of course, the real power of NavisWorks lies in its ability to combine multiple models, and an example of this is shown in Figure 2, which combines separate architecture, structure, and MEP models that were exported from their respective Revit BIM applications into a consolidated file that can now be reviewed as a whole. As shown to the left of the graphics windows, the Selection Tree automatically provides a hierarchical listing of the model components, starting with the files they came from followed by their floors and so on, making it easy to select and view different parts of the model. As with earlier versions, a model’s scale, rotation, and origin can be easily changed to synchronize it with the other models.

Figure 2. A new NavisWorks file created by consolidating three different models exported from Revit. The Selection Tree is being used to select a specific group of components in the structural model, shown in blue.

While the example shown in Figure 2 demonstrates the use of NavisWorks for multi-disciplinary real-time visualization and review, it can also be gainfully used within a single discipline. For example, if an architectural model in Revit is large and has been sub-divided into multiple linked models, they can be brought together as a whole in NavisWorks instead of in Revit—it would be much faster in NavisWorks because of the compression technology that it uses.

In addition to the various navigation tools I described in my review of NavisWorks3, there are now tools that can constrain the navigation to collision detection and gravity, providing a more real-world experience. You can also choose to display an avatar navigating through the model, providing a third person view and a sense of scale, as shown in Figure 3. While the navigation experience is nothing as slick as the experience of walking or flying around in virtual worlds such as Second Life (see my article on Second Life published last year), it is certainly functional and adequate for reviewing the model. Views can be saved for easy access in the Viewpoints palette.

Figure 3. Navigating the interior of the combined model shown in Figure 3, using the Third Person tool.

Other visualization and review capabilities remain almost the same as in the version I reviewed previously. You can create and save selection sets of similar objects by searching for items having a common property or combination of properties. Figure 4-a shows an example of the Find Items tool being used to search the model for all the exterior wall types that are brick on metal stud, and then saving the results of the search as a selection set for easy retrieval later. What is also impressive is that these search selection sets are dynamic, which means they will automatically update the selection if the model is modified and re-imported or if a new model is added. You can also export these search sets to reuse them on other projects. Figure 4-b shows the same model but with a large number of additional selection sets that were imported into the project. Items that are selected can be viewed in isolation to study them better, or they can be hidden to examine other elements more closely.

Figure 4. (a) Searching the model to select all items having a specific property and then saving those search results, shown in blue, as a selection set. (b) Using additional selection sets that were imported into the project.

In addition to selection sets, other useful features that make it easier to explore different parts of the model include smart tags that display pop-up information about an item by moving over it without having to select it, sectioning tools that allow up to 6 sectional cuts to be made in any plane while still being able to navigate around the scene, a choice of four interactive lighting modes and four different rendering modes, and a set of tools for measuring distances, areas, and angles in the model. You can also create animations to be able to share specific aspects of the model with others. This can be done either by simply recording a real time walk through, or by assembling specific viewpoints that are then interpolated into an animation.

A critical part of the review process is being able to mark up models, and NavisWorks allows you to do this by adding comments and other redline marks to the model. Figure 5-a shows the Redline tool being used to add a comment tag to an object. A new viewpoint for that tag is automatically added to the Viewpoints palette, making it easy for reviewers to quickly see the comments and the objects they relate to. It is also possible to export a Viewpoints report in HTML format, as shown in Figure 5-b, which lists all the viewpoints, showing a screenshot of the tagged item and any comments associated with it. This allows the review comments to be distributed to a wider audience without requiring them to use any additional software other than a browser.

Figure 5. (a) Adding a redline tag to an object in the model. (b) The HTML report exported from the model that shows all the redlined views and associated comments.

The combined set of models that has been used so far can be published as a single highly-compressed NavisWorks .nwd file, which can then be viewed by those willing to download and use the free Autodesk NavisWorks Freedom application. This also ships with all the paid versions of the product. As shown in Figure 6, the interface of Freedom is very similar to the other NavisWorks applications, except that it has a reduced toolset that only allows for model viewing and navigation and for reviewing the comments that have been added. It retains the viewpoints from the original file, allowing the user to quickly navigate through the redlined views and see the associated comments. It does not have any markup capabilities, so it cannot be used to actually participate in the review process.

Figure 6. Viewing the single published model with the free NavisWorks Freedom application, and using the saved views to go through the comments that have been added.

In addition to publishing the model as a NavisWorks file for viewing with NavisWorks Freedom, it can also be exported as a 3D DWF file which can then be used with Autodesk Design Review, also a free application. (See the recent review of Autodesk Design Review 2009 published in AECbytes.) Also available is the ability to publish the model as a KML file that can be subsequently geo-located and viewed in Google Earth in the context of the actual site of the project.

4D Construction Simulation and Enhanced Visualization

Let’s move on to look at the additional construction simulation and visualization options that are available in the higher level products, NavisWorks Simulate and NavisWorks Manage. The 4D construction simulation works by linking the 3D model with a construction schedule, which can be brought in from popular project scheduling applications such as Primavera P3 and Microsoft Project. NavisWorks can also work with task schedules in the common MPX format created by other applications such as Primavera SureTrak. All the individual tasks from the linked task schedule file can be imported, associated with a task type such as Construct, Demolish, or Temporary, and finally, assigned the model items that need to be associated with them. Items can be selected and manually attached to tasks, or if the task names correspond with the names of layers, selection sets, or the items themselves, the assignment can be made automatically using the appropriate rule. After all the items in the model have been assigned to tasks, the display settings for the simulation can be defined and the simulation can be played, showing the sequence in which the project will be built. Figure 7 shows the simulation created in the Timeliner by importing a basic schedule that had been created in the MPX format. The convenient visual feedback allows many what-if scenarios for the scheduling to be explored so that the construction time and other aspects of the project can be optimized.

Figure 7. Creating a construction simulation using the Timeliner capability, with the help of a schedule imported in the MPX format.

In addition to construction simulation, the Simulate and Manage products have some additional visualization capabilities that are not available in the entry-level Review product. One of these is the ability to use the material data that is included when a model is brought in or apply new materials to objects, as well as apply lighting and other effects to the model to create photorealistic renderings. This comes from the Presenter plug-in of the earlier version of NavisWorks, and was described in my review of NavisWorks3. While the quality of the renderings can hardly be described as mind-blowing, it does allow NavisWorks to be used as a convenient and low-cost alternative to a full-blown rendering application like 3ds Max.

Another visualization feature is object animation, and this is new to NavisWorks 2009. Not only can you add animations to objects, you can also write scripts to control the animation. A common use of object animation would be to add more realism to the model. For example, you could have a script that automatically opens a door when the user navigating through the model arrives within a certain distance of the door. This is particularly important if the Collision Detection option has been turned on, which will prevent the user from getting inside the building by walking though the walls or glass. You could also have object animations that show the movement of vehicles or cranes around a construction site. While users don’t have to be expert programmers to be able to create these object animations and scripts, it does take some extra effort to learn to do this, and I don’t expect it to become a heavily used feature of the application.

Interference Checking and Clash Detection

Finally, let us take a look at the interference checking and clash detection capability that is only available in the NavisWorks Manage application. Again, this has not fundamentally changed since I last reviewed NavisWorks. It works by selecting the elements or element groups that are to be checked against each other, specifying a tolerance value, and setting options for clash type and interference method, after which the clash test can be run. The results window lists all the detected clashes, and allows each instance to be inspected more closely in the graphics window. Figure 8 shows the clash detection being run to check the interference between two groups of elements, the Supply Air System from the MEP model and the Structural Framing in Steel from the structural model. These were selected from the selection sets that were earlier imported into the model, shown in Figure 4. As you can see in the Results window, five clashes were detected, of which the third one is currently being inspected. Various display options are available so that the clashing elements can be seen more clearly.

Figure 8. Setting up a clash detection between two sets of elements, and reviewing the results.

Clashes can be set to a different Status depending upon whether they are new, active, approved, or resolved. Some clashes can be approved as they are, but some would require changes to be made to the models in the original authoring tools, as NavisWorks does not include any object editing capabilities. If AutoCAD and MicroStation were the original authoring applications, there is a convenient SwitchBack option that takes you directly back to that application with the model open and zoomed at the correct spot of the clash, allowing it to be conveniently modified to resolve the conflict. It can then be re-imported into NavisWorks for testing. An Update option is available for uploading all the changed files and re-running the clash tests.

In addition to the HTML and text formats for generating the reports capturing the results of the clash tests, a new feature is the ability to export the clash results as viewpoints. This creates a folder in the Viewpoints palette with the name of the test. Each clash is saved as a viewpoint in this folder, with a comment attached containing the clash result details. While this allows anyone with access to that NavisWorks file and the Freedom application to view the areas in which the clashes are occurring, it does not automatically highlight the clashed objects the way in which they are highlighted in the Clash Detective results window, so I found its usefulness somewhat limited.

Strengths and Limitations

Taking a detailed look at NavisWorks after a long gap of over four and a half years, what surprised me was how little the application has really changed, apart from some enhancements and the repacking into four separate applications. On the surface, this might seem like a bad thing as it could be indicative of a lack of progress in the application. On the other hand, it could also be reflective of how good the original application was that it warranted such little change over the last few years. It is also one of those interesting and unique cases in which an application grows in strength not because of its own development and enhancements, but because of the changing circumstances of the industry that it serves. Prior to the Autodesk acquisition, NavisWorks was a small company with limited resources. However, the product it had developed solved such a critical problem in the 3D and BIM workflow in AEC that the company didn’t really need to expend much effort on developing it further—it was probably spending most of its resources just coping with the growing demand as more and more firms started transitioning to BIM.

The key strength of the application continues to be its ability to import all the key 3D design file formats and combine multiple models into one file, with a powerful compression technology that allows them to be reviewed easily as a whole project, regardless of file size or format. Navigation options are plentiful, and the ability to save and import selection sets is extremely handy. The annotation tools are limited but quite adequate for marking up the model, and there are several options to share the review comments with others, including the free viewer application. The 4D construction simulation available in the Simulate and Manage products is much more powerful and intuitive than just relying on chart-based scheduling, and allows many more scheduling options to be explored. The benefits of interference checking and clash detection contained in the full-featured Manage product are already well understood and documented—the ability to coordinate the design fully prior to construction can greatly reduce change orders and construction errors, reducing waste and keeping costs under control. Other features such as object animation and the ability to generate photorealistic renderings are not mission-critical, but are useful to have for those who would like to use them. The application also continues to remain fairly easy to learn and use.
Of the limitations I had pointed out in my last review, the lack of IFC support has been fixed, but the minor interface problems I found earlier still remain. There is a surfeit of floating palettes which have unpredictable docking behavior, without a Reset option to take you back to the original layout. Also, it would be helpful to have a 3D-2D synchronized navigation ability so you could quickly navigate to the exact position required in the model instead of relying on tools such as Walk and Fly to make your way through where you want to be. In my last review, I had found the application somewhat overpriced, but given the tremendous value that it has demonstrated for its users in finding errors and avoiding change orders, the pricing now seems in line with the many benefits it is providing.

As I mentioned earlier, the core capabilities of the application haven’t really changed for the last several years. While this is not a limitation as such, I do think NavisWorks has the potential to do much more than what it currently does. For instance, it is able to read in object data from the models, but apart from using that to search the model and assemble selection sets, it is not using that capability in any meaningful way—most of its functionality revolves around the geometry of the building components. It would be great to see if this capability could be used for integrating with other applications such as cost-estimating, project management, construction management, facilities management, and so on, conceivably making NavisWorks the hub of many post-design, post-BIM activities. Also, while NavisWorks does not include any object editing capabilities, it would help to at least give it the ability to divide objects into parts for scheduling, for example, a single column spanning four stories that needs to be scheduled in four separate phases. This would allow the application to be used for accurate construction simulation even if the objects in the model have not originally been created taking the constructability perspective into account.


In my article last year on the AEC Technology Strategies 2007 Conference, I described a presentation by Jim Jacobi, Principal and Chief Information Officer at Walter P. Moore and Associates, Inc., a leading structural, civil, and transportation engineering firm, in which he provided an overview of the BIM implementation in his firm. This included the extensive use of NavisWorks to bring the different disciplinary models created in different BIM applications together for electronic review and conflict detection, substantially reducing field rework and improving schedule and cost reliability. Jacobi found the ability afforded by NavisWorks to walk through the facility with all the models in place so empowering that he expressed surprise that the application wasn't mainstream yet, given that it was such a “breakthrough technology.”

I would say that in the span of 16 months since that comment was made, NavisWorks is well on its way to becoming a mainstream application in the AEC industry, given that it now has the tremendous market reach and development resources of Autodesk behind it. It has become critical to the BIM workflow by allowing individual disciplines to use the application they prefer and not be forced to work on BIM applications built on one platform. Ironically, it is NavisWorks that diminishes the need for architects and engineers using non-Autodesk BIM tools to switch to Revit just for the sake of compatibility with the other disciplines! 

It remains be seen what direction NavisWorks will take now that it is part of the Autodesk family of products. A deeper integration with Revit would certainly open up some really exciting possibilities. I hope that Autodesk focuses more on broadening the scope of the application going forward, while continuing to remain supportive of all file formats, rather than narrowing it down to work more closely with only its own products.

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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