Viewpoints are the means to effective clash detection inside Navisworks for use with point clouds or otherwise. Saving viewpoints with section planes or boxes lets us better isolate areas of the building and more importantly, digest point cloud data clashing against model geometry.
Note: the following steps only apply to Autodesk Navisworks Manage or Simulate.
Here's our procedure to section the model (including the point cloud), save a viewpoint, and run clash detection in Navisworks:
1. Import (using the Merge or Append function) the point cloud into your overall model and align as needed.
2. Start with the Saved Viewpoints window (View Ribbon > Windows) and pin the window as you'll need it later.
3. Click the Viewpoint ribbon and choose “Enable Sectioning” to the far right.
4. Create a section box. In the new ribbon called “Section Options,” click the Planes dropdown and choose “Box.” The section box is much more efficient at isolating a portion of the model for clashing. From there you can use a combination of the Move, Scale, and Rotate options found in the ribbon until you have a box that properly encompasses the space. Remember that each point hitting solid model geometry is a clash, so this box shouldn't be terribly large to avoid sorting through 1,000+ clashes.
5. Save the viewpoint by right-clicking inside the Saved Viewpoints window and choosing “Save Viewpoint.” This will be our template for clash detection. Make sure it's the last viewpoint you select before hitting the “Run Test” button below.
6. Enable the Clash Detection window in the View ribbon using the Windows dropdown.
7. Create a test in order to select the proper geometry. We usually isolate electrical, mechanical, and fire protection as separate tests against each other, structure, or in this case a point cloud.
8. In the Select tab, choose the two files that you will be clashing against. Make sure you have the points button enabled.
Finally, click the “Run Test” button in the Select tab to see the results.
9. That's it! You have clashed your point cloud with model geometry. The usual approach at this point is to group clashes into common issues. For example, if a row of conduit is clashing with a soffit, we consider that one clash and all corresponding clashes can be grouped into a single clash group to better consolidate the overall problem.
Zack Creach is a senior engineer for Holder Construction in Atlanta.