Autodesk Navisworks was mentioned in a previous post as our primary clash detection tool. Aside from simply bringing in the point cloud and visually confirming the models match, we can also use the Clash Detective window within Navisworks to coordinate what's been built versus what's about to be installed with significantly more intelligence than a walk-through of the model.
One thing critical to understanding Navisworks Clash Detective is that you will only clash items that are visible in the model. In other words, if you have hidden the structure model (floors, columns, beams), for example, Clash Detective will not show any issues. Put another way, Navisworks only clashes what it is visible and unhidden in the model. What you see is what you clash.
For that reason, we often use section planes/boxes to divide large projects into more manageable areas/sectors. When you section a particular area, you will only clash with the visible portion of that view. This is particularly useful for point clouds. By applying a section box (or planes) to a portion of the model, we can better isolate clashes between individual points and solid geometry (i.e. conduit).
Denser point clouds are actually less ideal in the realm of clash detection. The reason being: more points equals more clashes. We recommend reducing the number of points in your point cloud file prior to bringing it into Autodesk Navisworks.
Zack Creach is a senior engineer for Holder Construction in Atlanta.