NavisWorks3

This issue of the AECbytes Product Review series takes a look at an application in the relatively new genre of 3D design publishing and review. Currently in version 3.3, NavisWorks was launched by the UK-based company, LightWork Design (developer of LightWorks, the leading 3D rendering engine), and spun off as a separate company in 2002.

What started off as a base level viewer and visualizer of 3D CAD models has matured into a product that can access all the popular 3D design file formats, has the ability to combine multiple models into one file, comes with an Application Program Interface (API) for customization, and includes plug-in modules for advanced capabilities such as interference checking and 4D construction simulation. With the growing interest and push towards 3D building modeling, applications like NavisWorks will become increasingly critical as a means to view and collaborate on 3D content outside of the one or more 3D authoring applications that create it.

Before looking at NavisWorks in detail, a quick overview of this new genre of applications should help to place it in the right context.

The New Genre of 3D Viewing, Checking, and Presentation Software

Current electronic publishing solutions such as PDF and DWF are primarily geared towards 2D drawing content. With the increased adoption of 3D modeling, a new genre of software solutions is emerging to address the need to visualize, review, and present 3D content outside of their authoring applications. Some applications in this genre I have reviewed over the last two years include o2c_Interactive!, Solibri Model Checker, and QuadriSpace Presenter.

Built on the highly-compressed, Internet-deliverable o2c format, o2c_Interactive! is an application that allows designers to interactively navigate through 3D content online, explore and present different variations of material finishes for 3D objects on the fly, and generate high-resolution photorealistic renderings of selected alternatives (see my review of this application). A low price tag of $149.95 makes the application very affordable, but its scope is mostly limited to exploring material alternatives for a design project.

At the other end of the cost spectrum is the $4,500 Solibri Model Checker, a tool for "design spell checking" of a building model in the IFC format to detect potential problems, conflicts, interferences, or design code violations, and ensure the integrity of the model to downstream building analysis applications. It has a good visualization interface, allowing viewing and walk through of the model, and enables parametric constraints for checking that can be configured to desired standards, which explains the high price tag (see my review of Solibri).

The third application, QuadriSpace Presenter, is a 3D publishing and presentation solution that falls between these two extremes from a cost perspective. Priced at $1,495, this is a tool for creating interactive multimedia presentations combining navigable 3D models, animation sequences, and , intended for use by design professionals to present their design concepts to clients. It includes some powerful features such as the ability to record animation sequences in 3D models and include these sequences in the presentation, the ability to synchronize a 3D model and the corresponding 2D vector drawing so that the position in the floor plan can be monitored during navigation through the 3D model, and collision detection in walkthrough animation (see my review of QuadriSpace Presenter).

NavisWorks includes a suite of several different tools that together provide many of the capabilities of the applications just described. The entry level solution is Roamer (priced at $950), which opens 3D design files in the most popular file formats, allowing review of geometry, object information, and materials (see Figure 1). The other NavisWorks tools are available as plug-in components for Roamer: Presenter ($450) is an authoring application that allows textures, materials, and lights to be applied to the 3D model and creates both still and animated photorealistically rendered output; Publisher ($1500) creates compressed and secure review files for sharing with other team members and clients, which can be viewed and navigated with Freedom, a free 3D viewer; Clash Detective ($4000) allows the geometry created by different 3D design applications to be reviewed together and checked against each other for interferences; and finally, TimeLiner ($1250) allows task schedules to be linked to 3D model data for performing 4D construction simulation.

Let us now move on to look at the key NavisWorks tools in more detail and see how its capabilities compare with those of the other applications in the 3D publishing and review genre.

Roamer: The NavisWorks Hub

You start in NavisWorks with the core application, Roamer. Here, you can open a 3D file in a variety of file formats including DWG, DXF, DGN, 3DS, IGES, and so on. Once a file is open, other files can be appended to it, allowing a complex scene to be built from a number of smaller models in the same or different file formats. If required, the scale, rotation, and origin of an appended model can be changed to synchronize it with the other models. The combined set of models can be published as a single highly-compressed NavisWorks .nwd file using the NavisWorks Publisher plugin, which can then be viewed with the free NavisWorks Freedom viewer. The files can also simply be saved an .nwf file. No geometry is saved in this format, but a list of appended files, along with their path relative to the .nwf file is saved, along with any overrides, color changes, comments, redlines, viewpoints, or other NavisWorks specific information.

Once the file or files have been brought into Roamer, their 3D content can be viewed and navigated in a variety of ways. NavisWorks guarantees interactive navigation of virtually any size model with a guaranteed frame rate, and I found this to be true. With eight different kinds of navigation modes-Zoom, Pan, Orbit, Examine, Look Around, Turntable, Walk, and Fly-the model can be easily seen from any desired angle. Complementing these modes is another set of navigation tools for aligning the current view along the X, Y, or Z axes, viewing the whole model or a selected element, setting the view to perspective or orthographic mode, and some other functions. A tilt slider is also available for controlling the tilt angle of the view, particularly useful in the Walk mode for looking up and down. Plan and section thumbnail views are available with a triangular marker representing the current viewpoint, as shown in Figure 1; this marker can be dragged to quickly relocate the camera to a different position within the model. Critical views can be saved for easy access in a Viewpoints palette, which also includes any saved views from the original file(s). In addition, preset views such as left, right, top, and so on are readily available as menu options.

In addition to navigation, NavisWorks provides an extensive set of options for selecting individual elements or element groups within the model. A Selection Tree palette provides a hierarchical view of the structure of the model, as defined by the CAD application in which the model was created. Using this palette, items can be selected at different levels: an individual item of geometry, a group such as a block or cell, a layer or level, or a whole model. Figure 2 shows an example of this hierarchical structure in the Selection Tree palette with the "restaurant seating" layer selected; all the corresponding items in the model are selected, as indicated by the blue selection color in the main graphics window. An option to search and select items by properties such as material, geometry, and so on is also available. Selected groups of items can be stored in the form of selection sets for easy retrieval later.

What can you do with selected items? For a start, you can hide them or hide all the other non-selected items. This is useful for a detailed look at the items themselves or at the objects they might be hiding. Figure 3 shows how this capability is used for temporarily hiding a roof element in order to examine its supporting structure more closely. This is where the capabilities of NavisWorks start to extend from navigation alone to design review as well. Additionally for selected items, you can temporarily override their color and transparency attributes to explore material alternatives, as well as any hyperlinks that were attached to them in the original authoring applications. These overrides are saved into the .nwf files for future use, but can be reset to their original values at any time.

Other design review capabilities include the ability to attach comments and new hyperlinks to selected items, and add redlines to saved viewports. These are also saved in the .nwf file and can be recalled when needed. Additional utilities in Roamer include a set of tools for measuring distances, areas, and angles in the model; 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, providing the ability to see inside models without hiding any item; and a choice of four interactive lighting modes and four different rendering modes. Animations can be created in Roamer in two ways: either by simply recording a real time walk through, or by assembling specific viewpoints that are then interpolated into an animation.

In addition to publishing to .nwd or saving to .nwf, NavisWorks Roamer has a few other output options. The current view can be printed or exported to one of three file formats: Windows BMP, JPEG, and Piranesi Epix. The option to export an animation as an AVI file is also available.

Presenter, Clash Detective, and Timeliner

As mentioned earlier, the other NavisWorks tools are available as separate plug-in modules for Roamer. They do not need to be installed separately, but simply require separate license codes that can be entered during the NavisWorks installation. If NavisWorks is to be used to create photorealistic output, the Presenter tool will be required. When installed, it is available as a menu option within Roamer and can be opened as a tool palette, as shown in Figure 4. From this palette, different materials, lights, and effects available in accompanying libraries can be dragged and dropped into the model. Textures automatically size themselves appropriately according to the scale of the model when they are applied to elements; if adjustments are needed, an option to edit them in texture space is also available. A Render button in the Presenter palette renders the scene photorealistically, complete with lights, shadows, and textures; the resulting image has additional export options such as TIFF and Targa, in addition to the basic options of Roamer. In addition to photorealistic output, Presenter can also produce renderings in a variety of sketch styles that are available under the Effects tab, along with a choice of background options and foreground effects such as fog and snow.

The most expensive application in the NavisWorks suite is Clash Detective, which allows the model to be checked for geometric interferences. From an AEC perspective, this can be used to check, for instance, a structural model and an HVAC model of the same building and detect and fix errors such as a duct passing through a beam. It is critical to fix such errors at design time rather than leave them unchecked till they are detected at the construction site, where they are so much more expensive to fix. However, since Clash Detective has no knowledge of building components as such and only works on the basis of geometry, it will be useful only when the building components in the original CAD applications are clearly differentiated into different categories such as walls, beams, columns, ducts, and so on by using layers, blocks, materials, and other grouping mechanisms.

Figure 5 shows Clash Detective in action to detect clashes between the outer skin and supporting truss of the same model. After 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, 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 by using the Auto Zoom and Dim Other options. Details of the clashed items can be reviewed for every clash. Clashes can be set to a different Status depending upon whether they are still active, approved, or resolved. And finally, reports in various formats, including HTML, can be generated that capture the results of one or more clash tests.

The latest entrant to the NavisWorks suite is TimeLiner, which further extends the capabilities of the model to perform 4D construction simulation. The TimeLiner plug-in within Roamer provides direct links to popular project scheduling applications such as Primavera P3 and Microsoft Project, and 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.

Strengths and Limitations

The key strength of the NavisWorks suite is its comprehensiveness. It has a complete repertoire of 3D navigation and design review tools, with the added capability of generating sophisticated renderings, detecting geometric interferences, and linking the model to project scheduling applications to generate time-based simulations. The Roamer application is able to handle even large models with ease-the files load quickly and the interactive navigation is very smooth with no noticeable jerkiness. Overall, the application is relatively easy to learn and use.

In particular, NavisWorks' ability to combine files of different formats into one model and synchronize them with relative ease is a tremendous feature that can facilitate cross-disciplinary collaboration in the building industry. The different disciplinary models such as architectural, structural, mechanical, and so on can be easily combined into the entire building model, which can then be reviewed in totality. This is particularly critical since most building design solutions are still stand-alone and discipline-specific, rather than integrated suites of architectural and engineering applications where this cross-disciplinary review is built in.

The biggest limitation of NavisWorks from a building design perspective is that it is a generic, geometry-based solution that works for any industry dealing with 3D design, rather than being a building-specific solution. One of the biggest limitations of traditional CAD solutions is that they represent only geometric entities rather than self-aware building entities, and it is because of the limited intelligence of these solutions that the AEC industry is gradually moving towards building information modeling or BIM (see my cover story, "Should We BIM?" in the June 2003 issue of Cadence). NavisWorks can read in the properties that have been attached to objects in the original authoring application, which can be used to search and categorize objects into selection sets for performing operations, but it has no intrinsic intelligence about the building model.

From that perspective, NavisWorks falls squarely into the CAD category rather than the BIM category. This makes it distinctly different from an application like Solibri Model Checker that represents building entities, understands about concepts such as space, wall, door, etc., and can be used to review the building model in a more intelligent fashion by checking for code violations, satisfaction of specified constraints, and so on. In contrast, the similarly priced NavisWorks' Clash Detective is based on geometry only, and can be used gainfully only if the original model has all the building elements properly categorized. Even then, it cannot match the effectiveness of an application such as Bentley Interference Manager that can detect spatial interferences between the architectural, structural, and HVAC models created in Bentley's integrated suite of AEC applications. At some point, other BIM vendors like Autodesk and Graphisoft are likely to provide similar integrated suites with built-in conflict detection capabilities, and this might diminish the importance of external geometry-based interference checking solutions like NavisWorks in the building industry.

Other limitations include the current lack of IFC support, an issue that is fast becoming critical from an interoperability perspective, and the relatively high cost of the entire suite. While the Roamer's price tag of $950 is easily justified by the extent of its capabilities, the Publisher module at $1500 and Clash Detective at $4000 seem over-priced, especially taking into consideration the lack of building element intelligence in the application. At this price, widespread adoption will be a challenge, and NavisWorks will likely be confined only to projects large enough to justify its cost. On the interface front, some minor improvements could be made: there is a surfeit of floating palettes which have unpredictable docking behavior, without a Reset option to take you back to the original layout. And even though the plan and section thumbnails (shown in Figure 1) are useful, they don't match up to the 3D-2D synchronized navigation ability that QuadriSpace Presenter offers, as described in the first section.

Conclusions

NavisWorks belongs to a new genre of 3D viewing and navigation applications that are needed in the AEC industry for allowing design content to be reviewed by clients and the extended building team without requiring the use of the original authoring applications. What makes NavisWorks compelling is the additional functionality of imaging, interference checking, and construction simulation that goes beyond just viewing and navigating. As electronic publishing takes off in the AEC industry, solutions like NavisWorks will become significant as alternatives to the 2D-based DWF and PDF.

However, as the industry moves away from CAD and towards the adoption of BIM, it is not clear whether a generic geometry-based application, designed for use across several industries, can fit seamlessly into a BIM workflow in the long run. If the company can develop a building-specific version of its product suite, NavisWorks can nicely complement the capabilities of existing and upcoming BIM applications rather than run the risk of being superseded by them.

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 lachmi@aecbytes.com.

Reviews > NavisWorks3 > Printer-friendly format