As we have discussed in the last two issues of LP360 News, breaklines are two- or three-dimensional graphic data (points, lines, polygons) that we introduce into an elevation model to alter the topology. When working with Geographical Information System (GIS) models, we nearly always model complex, irregular elevation data as a Triangulated Irregular Network (TIN). The source of the elevation points need not be from a LIDAR sensor. Surveyed mass points, scanned contour lines, correlated stereo models, and myriad other sources produce irregular elevation data that can be modeled as a TIN, and tools (such as LP360) that can manipulate random points are generally adept at processing these various data sources. Figure 1 is a point rendering of a typical airborne LIDAR scene that has been processed via automatic classification in LP360 (but not edited). Note that due to the high point density in this particular data set, features are recognizable even though the point cloud provides a fairly crude rendering.