Point Group Tracing and Squaring Property Page

*This feature is available in the Advanced license level of LP360.

About Point Group Tracing and Squaring

The Point Group Tracing and Squaring point cloud task is used to extract traced outlines around points of a particular classification value (e.g., buildings classification), and optionally the traced outlines can be squared producing an approximation of objects such as the roof outlines of buildings.

Extracted outlines are saved to shapefiles with attributes that describe the traced objects. Attributes captured for each object include Area, and if squaring the polygons fit metrics (i.e., RmsError, MaxErr, ForceFit). If squaring is performed, two shapefiles will be generated; one for the traced outlines, and other containing a "_sqr" suffix representing the squared outlines.

The Point Group Tracing and Squaring point cloud task is both an extractor and a filter. The filtering capabilities are limited to clean-up duties as described by the various reclassification options on the property page. When using any of the reclassifying options the point cloud data must be opened for read/write when using the tools on the LP360 Point Cloud Tasks Toolbar.

The Point Group Tracing and Squaring task assumes that points exist in the point cloud data on the selected boundary trace class, such as tracing outlines for buildings requires points classified on the building classification. If you do not already have points on your boundary trace class such as for the buildings example, use the Planar Point Filter to classify the points before executing the Point Group Tracing and Squaring extractor. These two point cloud tasks (i.e., Planar Point Filter, and Point Group Tracing and Squaring) can be combined into a one-step process by creating a macro and including a Planar Point Filter as the first task and then the Point Group Tracing and Squaring as the second task.

How to use the Point Group Tracing and Squaring Point Cloud Task

1. Use the Add Files command to open the LAS files that contain the data you want to use.  

2. Use the Add Task command to create a new point cloud task. When you are selecting a Task Type in the Add Point Cloud Task dialog, select Point Group Tracing and Squaring. Once you click OK, you should see the unique name that you gave your task selected in the list and the Point Group Tracing and Squaring property page displayed on the Point Cloud Task tab.

3. Specify the settings for the Point Group Tracing and Squaring operation in the Properties page that displays.

Picture of the Point Group Tracing and Squaring Property Page

Example of Point Group Tracing and Squaring

Example use to extract building outlines from points classified on the building class

Learn how to select a boundary trace class

Learn how to modify the units

Learn how to modify the grow window

Learn how to modify the trace window

Learn how to modify the minimum area

Learn how to classify point groups that are too small

Learn how classify points within small areas

Learn how select a classification for minimum area points

Learn how to classify points within the interior of outlines

Learn how to square the outlines

Learn how to modify the squaring angle

Learn how to dissolve overlapping polygons (e.g. vegetation outlines)

Learn how to modify the maximum patch area