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MikesNotes

-                      v22
+                      v23
-== todo ==
 == Mirror torsion error correction ==
 This shouldn't need to be done with newer LIDARs, but included here in case.  Leica suggests checking for torsion errors if there seem to be problems in the boresight calibration and reporting to them if found.
+TBD
+Visible sign of torsion error is a smile effect.
+Detect torsion by:
+ * choose highest altitude pair of crossing lines
+ * pick a point at nadir on one swath and at the edge on the other
+   * torsion will be at max for the edge swath and at 0 for the nadir swath
+ * take cross sections to see if there is any consistent vertical difference
 == Ground classification ==
 …
 Steps:
  * remove very low, noisy points from consideration first
+   * e.g. remove groups of up to 3 points > 1m below neighbours (iterate a time or two so it settles)
+   * e.g. remove groups of up to 3 points > 1m below neighbours (iterate a few times so it settles)
+ * classify groups of low points as ground (run N times to settle), takes account of neighbours
+ * repeat with singletons
+ * remove isolated points (>5m from any other point)
+ * manually "add points to ground" for areas that should be ground but haven't been classified as such (e.g. peaks of hills) and rerun process above
+Run as a macro.  Terra->tools->macro->new.