2012

Table Of Contents
File Terminology
cache files (.nwc) When any native CAD file is opened or appended, Autodesk Navisworks
creates a cache file (.nwc) if the write cache option is set. When the file is next opened or
appended, Autodesk Navisworks will read data from the corresponding cache file rather
than re-converting the original data if the cache is newer than the original file. If the original
file is altered, Autodesk Navisworks will re-create the cache file when it is next loaded. Cache
files speed up access to commonly used files. They are particularly useful for models made
up of many files of which only a few are changed between viewing sessions. Cache files can
also be exported from some CAD applications where a native file reader is not available with
Autodesk Navisworks. Cache options can be edited in the Options Editor (application
button
Options Model node).
external references External references (sometimes called reference files or XRefs) are
shown in Autodesk NavisworksSelection Tree as an inserted group. Autodesk Navisworks
looks for the externally referenced files in the same place as AutoCAD or MicroStation would.
If the Unresolved XRef dialog box is shown, then this link has somehow been broken
and the referenced files need to be relocated to where AutoCAD or MicroStation would
expect them to be.
If these XRefs are not important for the current session, then you can Ignore the reference
and the file will load without that XRef inserted. Similarly, Ignore All will load the file
without any unresolved XRefs.
You can also customize the options for the DWG/DXF and DGN file readers in the Options
Editor to set whether external references are loaded or not. This gives you more control
over file appending into Autodesk Navisworks.
faceting factor During an export from a CAD package to NWC format, or while Autodesk
Navisworks is reading a native CAD file, decisions must be made as how a curved surface is
reduced to flat facets. For most applications and file formats, you have control over the level
of faceting that takes place.
All items, no matter what their size, will use the same faceting factor and so have the same
number of sides to curved entities. Therefore, you need to experiment a little with different
values to account for the size that these items will appear on screen.
The faceting factor must be greater or equal to 0, where 0 results in the faceting factor being
turned off. The default value is 1, if you double the value you get twice the number of facets,
if you halve the value you get half as many facets. Larger faceting factors will result in more
polygons to a model and larger Autodesk Navisworks files. There is little point having a
large faceting factor if these curved entities are golf balls viewed from 200 yards!
For AutoCAD exports, the faceting factor is set from the NWCOPT command. MicroStation's
faceting factor is set from Options, which is available from the NWCOUT export dialog.
744 | Chapter 17 Glossary