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CHAPTER 2 Files and File Types
captures the current conditions or milestone events. This also includes clash tests and 4D simu-
lations, which will be covered in subsequent chapters. The file size of most NWDs is consider-
ably smaller compared to the corresponding CAD format.
NWC Fi l e Fo r m a t
NWC, or Navisworks Cache files, are generated when CAD files or laser scans are opened,
merged, or appended in Navisworks. They can also be created by using a designated file
exporter, which we’ll cover later in the section “File Exporters.” NWC files are read-only files
and can be thought of as a transfer mechanism to convert CAD, Autodesk Revit, and other
model data into a format that Navisworks recognizes. All geometry, relevant object property
information, and display settings from the original source files will carry over with the NWC
export. Once the file is opened in Navisworks, any changes made—such as redlines, markups,
viewpoints, or display overrides—cannot be saved back to this format.
When the native CAD format file is first brought in, Navisworks creates a file with the same
name but with the .nwc file extension in the same directory as the original source file. This is an
important concept of a successful Navisworks project, so keep in mind that good model man-
agement skills make this process easier.
When NWC files are opened, merged, or appended, Navisworks compares the original data
to the newly created NWC file and re-caches the file if data in the original file is newer than the
NWC. This ensures that as changes are made to the project design, they are reflected in your
Navisworks project. If no changes are detected, Navisworks opens from the original NWC file,
resulting in quicker loading. As a best practice, consider standardizing on using the Append
command instead of Open. Doing so reinforces this concept of file aggregation, which is an
important part of the overall project coordination process.
NWF Fi l e Fo r m a t
NWF files host no 3D geometry but rather contain links to the geometry from the original
native source files (see Figure 2.1). Besides the links, NWF files contain such items as markup
data, viewpoints, comments, graphical overrides, search/selection sets, TimeLiner, and Clash
Detective data. We’ll explore these topics in more detail in future chapters.
When working with the NWF file format, you’ll notice the file size for NWFs is extremely small
as compared to the NWC/NWD formats; however, remember the user must have access to the
original source files to view properly. As you work toward mastery of Navisworks, consider using
the NWF as the standard file format during your project. While NWD files can be thought of static
snapshots that capture specific milestones, using the NWF workflow is dynamic and allows for easy
updating of design changes from the original source files. Later in the book, you’ll explore clash
detection, 4D simulation, and other concepts, so having a good grasp of the file formats is crucial.
Figure 2.1
Source files linked
to the NWF file
format
NWF
Original Source Data Files
NWD DWG/NWC DGN/NWC
Laser Scan/
NWC
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