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    Revit Architecture 2012: Part 1


    Once a point cloud in any of these raw formats is imported, it gets converted to a proprietary Autodesk file format for point clouds, the "PCG" format. While the conversion takes some time, the resulting .pcg file opens up much faster because it is indexed. However, this additional data and faster processing does come at a price — the resulting .pcg file is much larger in size than the original raw point cloud data file.

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    While importing the point cloud into Revit, you can choose from different positioning options to place it where required. Once it is imported, all of the regular display and navigation options can be applied to it. You can see plan and elevation views, generate section views using the Section tool, view it in 3D from any desired angle by using the View Cube, and apply clipping planes to see different parts of it. You can zoom in and out, and the display automatically adjusts to the zoom level — showing more points when you zoom in and fewer points when you zoom out — so that the display system is not overloaded, and is faster and more responsive. The Visibility/ Graphic dialog for views now includes an additional option for point clouds, allowing you to display or hide them as required.

    While there is no feature recognition yet, let alone automatic conversion of the point cloud to a 3D or BIM model — which is undoubtedly the holy grail of laser scanning for architecture, engineering, and construction (AEC) — Revit does have the capability to snap to implicit planar surfaces that are dynamically detected in the point cloud, making it easier to create building geometry in reference to it. Thus, you essentially have to re-model the whole building in Revit, except that you can do it in reference to the point cloud and thereby attempt to ensure that the model more accurately captures as-built conditions.

    In the future, there are plans for automatic plane recognition, which would enhance the ease with which you can model "on top of" an existing point cloud in Revit. But of course, the ultimate goal is automatic conversion of the point cloud to a BIM model, which could be a long way off. In the meantime, Autodesk has opened up the APIs (application programming interfaces) for point cloud development in Revit, allowing third-party vendors to develop plug-ins providing additional point cloud functionality. A good example of this is the "Scan to BIM" application developed by IMAGINiT, an Autodesk reseller, which was exhibited at Autodesk University 2010. While it essentially provides the same functionality as what Revit now offers, we can look forward to additional innovations in the area of laser scanning for BIM, both from Autodesk and from third-party vendors like IMAGINiT who are using the Revit point cloud APIs.

    In addition to the point cloud support, other key enhancements to the Revit platform include the Revit Server and the Conceptual Energy Analysis capability, which were released for subscription customers in September 2010 and have now been included in the general 2012 Revit release.

    The Revit Server is designed to help project teams in different locations to more easily collaborate on shared Revit models across a wide area network (WAN). It comprises a central server in one location where the central Revit models of projects are stored, and local servers at each of the office locations, which maintain local copies of the models that users in that office are working with. Team members work on a local copy of the central model, accessing it through a LAN (local area network), and thereby avoiding the slow speed and latency problems that existed earlier when accessing the central model across the WAN. Additionally, the central server and the multiple local servers are being constantly synchronized to ensure that changes made to the local models are updated in the central model, which are then, in turn, updated in all the local servers in different locations.

    The Conceptual Energy Analysis capability, which is now available in the regular release of Revit Architecture 2012, allows energy analysis to be performed on conceptual massing models. The analysis works on a massing model that has been divided into levels; it automatically uses this to create an analytical energy model by rationalizing the form into thermal zones and building surfaces, based on parameters such as site location, construction type, percentage of glazing, and several additional attributes that come from the main project settings or are defined specifically for the energy analysis. For the glazing, you can also actually draw it on the building's surfaces instead of just going with a uniform distribution of the glazing percentage. The actual analysis uses cloud-based tools and provides an estimate of the energy consumption and lifecycle costs of the proposed design. You can also compare the analysis results of multiple alternatives by modeling them in Revit as different design options. You can view the results within Revit itself, enabling sustainability to be taken into consideration earlier on in the design process.

    In addition to the enhancements described above, all the Revit applications are now Citrix XenApp6 ready, supporting users working from remote locations using a single server. This can help to enhance collaborative workflows, especially when used in conjunction with the Revit Server to share Revit models across a WAN.

    Going Beyond Architecture: Construction Modeling and Shop Drawings

    Another key development in Revit is the introduction of new tools for construction modeling, which allows contractors, or even architects, to explore constructability of design models. It allows construction methods to be added to building components; for example, breaking up a wall into its individual layers or breaking up a single slab into separate parts based on the sequence in which it will be poured on site.

    Selecting a construction element activates a new Create category in the Modify ribbon, from which you can choose the Create Parts option. For a construction element made up of multiple layers of materials, you can simply select the Enter key to break up the element into parts based on its layers. You can now select and manipulate the layers individually by setting the new Parts Visibility option in the Properties dialog of the view to Show Parts, and by activating the Shape Handles option for the part. If an element has to be subdivided into smaller parts, you can select the Divide Parts option, which allows you to subdivide the element in different ways: by drawing on it using different drawing tools or by using intersecting references such as level lines and grid lines. If the parent element is modified, the corresponding changes are also made to the parts.

    Additionally, you can create a workplane that coincides with any plane surface and use the Workplane Viewer option to see that surface head-on, making it easier to draw on an element to subdivide it more precisely.

    The different parts can be made up of different materials from their parent element, if required. For example, you can have one slab with different floor finishes on different parts of it. For this, you would first break the slab into different parts based on its layers — assuming you have chosen a composite structure for the slab when it was created — and then subdivide the top layer of it, representing the finish layer, into multiple parts representing different finishes. Once the shape handles for the parts are turned on, you can graphically manipulate them independently of other parts.

    The different parts that an element is subdivided into can be scheduled independently. Just as with elements, schedules of parts are also interactive, so any modification made to a part graphically will automatically update the schedule. The part information can be passed on to applications like Autodesk QTO for quantity takeoff and to Navisworks for construction scheduling and other construction-related tasks. It should be noted that while these different parts can be scheduled differently for 4D construction sequencing, thereby enabling a more accurate construction schedule, they still belong to the same building element from a design standpoint.

    Another new but related functionality is the ability to combine multiple elements into an assembly. The tool for this, Create Assembly, is also in the Create category of the Modify ribbon. In a way, it is the reverse of the Create Parts tool, where you are subdividing an element into parts. With the Create Assembly tool, you are grouping related elements into a larger assembly, typically for construction purposes. Examples include a complex column made up of multiple smaller elements, a column with its associated rebar, etc.

    You can create an assembly by selecting multiple elements and providing the assembly with a name. You can then replicate the assembly wherever required. If you select the same set of elements and try to create another assembly, you cannot, as Revit detects that you have already created an identical assembly. Needless to say, you can also add and remove elements from assemblies if required. You can use this new functionality to create assembly views that are different from detail views, and create separate sheets for assemblies with plans, sections, 3D views, and so on.

    The primary use case of this capability is to create shop drawings for construction, although many architects are also using it to show millwork assembly and so on. It should be noted that unlike Revit families that are accessible from all projects, assemblies are specific to the project in which they are created and are only available within it. Also, assembly views are separate and do not interfere with the main model views.

    Both these new capabilities for creating parts and assemblies are available in Revit Architecture 2012 as well as Revit Structure 2012, enabling design models to be used more easily by contractors, instead of the contractors having to start over and create a construction model from scratch.

    Discuss this article in the Architecture Forum...

    Lachmi Khemlani is the founder and editor of AECbytes, an online publication focused on researching, analyzing, and reviewing technology products and services for the building industry. She has a Ph.D. in architecture from the University of California, Berkeley, specializing in intelligent building modeling; a professional B.Arch. (honors) degree from the Indian Institute of Technology in Kharagpur, India; and an M.Phil. in architecture from the University of Cambridge. Khemlani has worked on design projects as a practicing architect, authored books on CAD and modeling, and taught CAD and 3D modeling at UC Berkeley. She currently consults and writes on AEC technology.

    This article is excerpted from "Revit Architecture 2012" by Lachmi Khemlani, copyright © 2011, with permission of the publisher, AECbytes.



    ArchWeek Image

    Revit's implicit snapping capability allows objects, such as the wall shown here, to be modeled using the point cloud as a reference.
    Image: AECbytes Extra Large Image

    ArchWeek Image

    Point clouds can facilitate the creation of models that more accurately reflect as-built conditions.
    Image: AECbytes Extra Large Image

    ArchWeek Image

    The Revit Server feature allows team members in different offices to collaborate on models. This capability was first made available in the subscription update to Revit Architecture 2011 in September 2010.
    Image: AECbytes

    ArchWeek Image

    Another such feature, now also included in the general release of Revit Architecture 2012, allows energy analysis to be performed on conceptual massing models.
    Image: AECbytes Extra Large Image

    ArchWeek Image

    A grid can be used as an intersecting reference to divide a single floor slab into multiple parts. The part schedule for the subdivided slab is also shown.
    Image: AECbytes Extra Large Image

    ArchWeek Image

    Using the Create Assembly command, multiple model objects comprising a single structural element, such as this reinforced concrete column, can be combined to create a specialized group called an "assembly." Multiple instances of the same assembly can then be placed within a model.
    Image: AECbytes Extra Large Image

    ArchWeek Image

    The primary purpose of an assembly is to enable creation of shop drawings such as this one, for use during construction.
    Image: AECbytes Extra Large Image


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