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Supplemental Info for ICTWS IGNITE! Talk

Playing with point clouds: what a conifer forest looks like from above

The video below shows a 50m radius clip of airborne lidar data collected on the Idaho Panhandle National Forest in 2016. This point cloud has been height-normalized (so all the trees look like they are on flat ground), and the video walks through four steps:

  1. We start by looking at different angles of the point cloud, colored by height above ground; as you can see there are enough points to allow us to view individual features of this forest -- with the ground in dark blue and tree tops mainly in red/orange.

  2. We switch to looking at the same plot but with the ground points removed, and the trees all different colors, based on an Individual Tree Detection (ITD) algorithm run in R (from the lidR package); this lets us get a better glimpse of what each tree looks like, and you may even spot a few snags

  3. We switch to focusing on the snags that were surveyed in the field (red, showing all points within a 3m radius of the center)

  4. We isolate those points around each snag, to get a better look at the canopy structure surrounding each; you can discern the standing dead tree at the center of each, and notice the partial live tree canopies creeping in at the edge of these 3m-radius clips

How can canopy gaps help us detect standing dead trees?
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