Overview
The move to a BIM-centric design methodology as part of an integrated project delivery (IPD) strategy creates the need for a new responsibility and role within the organization: the model manager. Whether a full-time dedicated position or a secondary assignment to a manager with other responsibilities, the role is essential for facilitating model integration and maximizing the model’s utility to all of the parties across the project organization.
The model manager typically creates a Model Coordination Plan that establishes standards and lays out a framework for how the pieces that will be integrated into a composite project model will be created, shared, transferred, documented, and published. Standards and best practices must be established regarding software preferences, naming conventions, file transfer methods, and file sharing and editing permissions.
While model viewing software solutions, such as Autodesk® Navisworks® products, help make it relatively easy to integrate models from a wide variety of sources and in many file formats, each file format option has advantages and disadvantages. An experienced model manager must become familiar with the implications of these format differences on downstream workflow and recommend preferred choices.
Very few project teams work on a single software platform that all members can share. It is much more common that project team members each work with their own preferred software tools, and the outputs of these tools must be integrated to create a composite project model. For these teams, software that can aggregate many disparate models into a single analysis and viewing environment is essential.
In this lesson, students will explore the model importing capabilities of Autodesk®Navisworks® Manage software to create composite models that can be viewed and explored.
Model Management
Navisworks® Manage has its own native file formats (.nwd, .nwf, .nwc), but it can also import models created by many other modeling tools using common BIM and CAD file formats, such as the ones listed in the table below.
Creating a Composite Model
To prepare a model for review by the entire multidisciplinary team, it is essential to unite the models prepared by each discipline into one shared reviewing environment, such as Navisworks® Manage.
Many different types of models can be integrated into the composite model, depending on the specific needs and the nature of the project. For example, these might include site, existing utilities, existing buildings, roadwork, temporary structures (formwork or scaffolding), finished structure, architectural shell, MEP, and so on.
Creating a composite model requires an understanding of the available 3D modeling applications and their associated export and import functionalities. To aggregate the models in Navisworks® Manage, they must be exported to the native NWC file format or one of the other compatible 3D formats, such as DWG or IFC.
Each file format has its own strengths and limitations. So the project team should create and deploy a Model Coordination Plan within the design and construction team to avoid potential file and data compatibility problems.
Figure 5.1.1 - Navisworks Manage imports models using many common 3D file formats
Exploring a Composite Model
Having created a composite model that integrates models from the various design team participants, the team can now explore and interact with the unified composite model. Viewpoints of interest can be saved for later review, analysis, and presentation. These viewpoints might focus on finite issues requiring resolution, or, might present big picture views that show the interaction of building systems.
To create special scene views that more clearly communicate the design intent, model managers can:
- Use different camera positions.
- Hide or require selected elements or categories of elements.
- Change color and transparency overrides of individual elements or categories of elements to emphasize or diminish their appearance.
Viewpoints—snapshots of the model as it is displayed in the scene view—can be used for more than just saving a specific view of the model. Model reviewers can add annotations with redlines and comments that create a design review audit trail. When viewpoints are recalled, the redlines and comments saved with the viewpoint also appear.
Viewpoints can also save the color and transparency overrides, hidden items, section planes, navigation speeds, and modes that best convey and communicate the issues discovered during the model review. This guarantees that when someone reviews the viewpoints, they will see a view model that displays the information exactly as you intended.
Defining Sets of Model Elements
BIM models can contain detailed information that describes the properties and parameters of the model elements in addition to the geometry that enables the models to be utilized throughout the full lifecycle of the building. Navisworks® Manage enables reviewers to interrogate and use this information for many design, construction, and operational purposes without the need for the originating design software.
To prepare for the different types analyses that will run at various project stages, it is typically useful to create “intelligent” groups or sets of objects. These can be created as:
- Search sets—specified by finding items based on search criteria to select items having a common property or combination of properties.
- Selection sets—specified by selecting items directly in a scene view or in the element selection tree and manually assigning them to a set.
The most efficient method depends on how elements are organized by name or in the selection tree hierarchy. Generally, if search sets can be used, they offer the quickest method and can be saved and exported to other projects. While the method used to create sets can differ, the sets defined can be used interchangeably in analysis.
Sets can be used to facilitate many type of analysis, for example, to:
- Perform clash detections between model objects.
- Link model elements to schedule tasks.
Add material, light and effects for rendering. {/sliders}
Learning Objectives
After completing this lesson, you will be able to:
- Understand the importance of creating a composite model to facilitate whole project viewing.
- Describe the options available and tradeoffs of exporting and importing models using different file formats.
- Apply the concept of transforms to align separate models.
- Appreciate the value of creating and saving scene views to communicate design intent and document the model evolution through the project stages.
- Interrogate the composite model to explore how the integrated models relate to the whole.
- Create sets of elements that cut across all models and develop a model hierarchy for the integrated composite model.
Tutorials
Creating a Composite Model
In this exercise, you will learn how to:
- Export model files to different file format supported for transferring model information to Navisworks Manage (including NWC, DWG, and IFC).
- Set the appropriate global options for working effectively in Navisworks Manage.
- Open and append multiple model files to create a single composite model.
- Transform individual models to provide the proper alignment and positioning in the composite model.
Figure 5.1.2 - Setting the global options in Navisworks
- Export the Revit plumbing model named MEP_Plumbing.rvt to a NWC file using the Autodesk Navisworks 2010 Export Utility Add-in. Make sure that Geometry Compression is not enabled in the export settings.
- Export the Revit lighting model named MEP_Lighting.rvt to an IFC file.
- Open the composite model file named Unit5_Lesson1_Exercise1_Start.nwf, then append the two exported files—MEP_Plumbing.nwc and MEP_Lighting.ifc—from the previous steps.
- Adjust the offset of the MEP_Lighting.ifc to bring it into alignment with the composite model. Select the model in the selection tree, then click the Item Tools tab, and choose Move. Transform the model -20 feet (-6.10 m) in the x-direction by entering -20 into the pull-down menu.
Figure 5.1.3 - Transforming the Lighting model to new coordinate positions
Exploring a Composite Model
In this exercise, you will learn how to:
- Interact with the composite model in the scene view using the orbit, walk-through, and sectioning tools.
- Explore the hierarchy of elements in the composite model in the Selection Tree.
- Manipulate the appearance of elements in the scene view using the Hide, Require, and Override commands.
- Create and save viewpoints of interest that feature different systems or aspects of the model.
- Publish the model as a compressed .nwd file for sharing with others.
Figure 5.1.4 - A viewpoint employing a sectioning plane
- Create new viewpoints to illustrate specific points and features to reviewers of the composite model. Apply hide, require, and overrides to emphasize the key elements and eliminate extraneous items from each viewpoint saved. Create these viewpoints:
- Structural Frame-Overall—an overall view that isolates the Structural_Model and hides the other models.
- Structural-MEP—an overall view that shows the structural and MEP models and hides the Architectural_Shell.
- Restroom-Wet-Wall-Top—a perspective view of a restroom from the top and with a green color override to draw attention to the plumbing model.
- Exposed Ceiling-Level 1 Retail-Section Box—an internal camera view created by walking into the Level 1 retail space and aiming the camera up at the ceiling with the Look Around tool.
- Create new folders named Plumbing, Structural, and Mechanical to organize the viewpoints. Then move the new viewpoints into the appropriate folders that match their discipline.
- Save a new copy of the master NWF file to capture these changes and the current state of the composite model.
Figure 5.1.5 - Viewpoint of all Autodesk® Revit® Structure and Autodesk® Revit® MEP elements
Defining Sets of Model Elements
In this exercise, you will learn how to:
- Interrogate the composite model to find particular elements.
- Define selection sets of like elements that include elements from several of the appended models.
- Define search criteria to select sets of elements that share common properties or parameter values.
- Merge previously defined selection sets and organizing the sets into folders.
Figure 5.1.6 - Using the section box to expose the building systems in a 3D view
- Open the downloaded .NWF file in Navisworks Manage.
- Create a multicriteria Search Set, called Wood Framing, that contains the wood framing elements that meet at least one of the following constraints:
- Item Name Contains timber
- Item Name Contains joist
- Item Name Contains pine
- Item Name Contains wood
- Create a Selection Set, called Windows & Doors that includes all the windows and doors of the model, regardless of the family type.
Figure 5.1.7 - Selection set of the wood framing elements
Assessment
Creating a Composite Model
- Is there a limit to the number of models that can be appended to a composite model?
No.
- Navisworks Manage can also publish a composite model in the NWD file format—a highly compressed formation that cannot be edited and can be secured with password protection. For what purposes would this file format be useful?
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The NWD file is the recommended format for sharing the entire project with all stakeholders, enabling individual disciplines to see how their design fits within the overall project while protecting the original designs.
NWD files can be reviewed in the free viewer, Autodesk® Navisworks® Freedom software, as well as in the full Navisworks® Manage program if the ability to add markups and carry out full analysis of the project is needed.
- Considering that there may be several different audiences for the composite model, each with their unique set of concerns, would it be useful to save several different NWF files of the composite model? What might an NWF file to be shared with the project owner contain, as compared to an NWF created for the MEP consultants?
Yes; although each NWF file is based on the same composite model, the actions and viewpoints saved in each NWF could be quite different. This approach respects the needs of the various audiences, all of which may have differing objectives and reasons for using the model.
Exploring a Composite Model
- What techniques can you use to filter the information displayed in a scene view?
Scene views can filtered using the Hide, Require, and Override commands to emphasize the critical elements and deemphasize the model elements that provide context but are not central to the issue being illustrated
- What might be conditions under which we would not want a viewpoint to retain the saved hide/require and overrides, but instead to inherit all the real-time settings in the course of our view navigation?
Locking the saved hide/require and override settings for a viewpoint can limit the flexibility available to experienced model reviewers as they navigate though a model in Navisworks Manage. Experienced reviewers may prefer to save only the camera position, so their preferred hide/require and override settings are not lost when a new viewpoint is opened.
- Can you cut a section view using a cutting plane that is not vertical?
Yes. You can use the rotate tool upon any given section plane when sectioning is enabled. The viewpoint saves section plane angles on a per-view basis so that the section planes in other viewpoints are not affected.
Defining Sets of Model Elements
- Can you describe a quick method for merging two existing search sets into a joined set?
Select both search sets in the Sets dialog box, then define a new selection set which captures all of the selected items (the union of the two sets).
- Can you edit the search constraints that define a search set after it has been created?
Yes. Select the search set in the Sets dialog box, and then use the Find Items tool to modify, add, or delete search criteria as desired.
Key Terms
Key Term | Definition |
Selection Tree | The hierarchy of the files users have opened and appended into the current scene and the model elements in each of these files. This hierarchy reflects the structure of the data created by the original design application. |
Viewpoints | Viewpoints are saved camera positions and view settings that allow model reviewers to capture and easily return to specific views of the model. Viewpoints can also store information that facilitates design review audit trails and setting up model animations. |
Orthographic | A mode of view displaying all the points of a model being projected parallel to the screen, and thus making it easier to work with a model due to all the edges of the model appearing as the same size, regardless of the distance from the camera. |
Perspective | The mode of view as we see things in the real world, where with increasing distance objects recede. |
Selection Set | Selection sets are static groups of items used for saving a group of objects that you want to regularly perform some action on. They simply store a group of items for later retrieval, and do not dynamically update as the model changes. |
Search Set | Search sets are dynamic groups of items selected by specifying search criteria. They are used in ways similar to selection sets, but the search criteria can rerun at a later date to update the search set when the model changes. |