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 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
VisualizationLet’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.
Strengths and LimitationsTaking 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.
ConclusionsIn 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!
Read the full article: http://www.aecbytes.com/review/2008/NavisWorks2009.html
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