Why do you need to use buffers around breaklines?

LIDAR points are so dense that when introducing breaklines into a surface using LIDAR points, the points overwhelm or over-weight the introduced breaklines. By removing a buffer of LIDAR points around the breaklines, the weight of the points against the breaklines are reduced allowing the surface to be "constrained" to the breaklines.

Example of using NO buffer


Example of using a buffer


Technical feasibility also dictates the need for a buffer around breaklines. On many occasions points may fall along the edge of a breakline. Using breaklines when triangulating, requires that no triangle edge can cross a breakline thus allowing the surface to be "enforced" by the introduced breaklines. When a point falls along the edge of a breakline, a zero area triangle is formed between the LIDAR point and breakline segments. This condition creates the potential for division by zero errors and fails to create a surface.

Are the buffer classes still part of ground?

Yes, the points are put on the buffer classes for breakline enforcement only. When breakline enforcement's are not being used, the buffered points should be selected as part of the ground classes when modifying the Display Filter, otherwise gaps (i.e., the buffers around breaklines) in the LIDAR data will be prevalent.

How do I classify points within a buffer of my breaklines?

• Classify by Features Dialog
  
  
• Elevation Conflation Dialog