normalizeH: Normalize photons height
In mqueinnec/icesat2R: Downloading and processing ICESat-2 data for forest analysis

Use local polynomial regression fitting with degree 0 (moving average) to interpolate ground surface and normalize photons using the interpolated surface

normalizeH(
  df,
  h = "h",
  beam = c("gt1l", "gt1r", "gt2l", "gt2r", "gt3l", "gt3r"),
  gap_dist = 10,
  min_ph_gap = 20,
  method = "loess",
  returnGaps = TRUE,
  keep_cols,
  dist_along = "cum_dist_along",
  segment_id = "seg_id",
  segment_idx = "seg_idx",
  ph_id = "ph_id",
  beam_n = "beam",
  ATL08_class = "ph_class"
)

`df`	Data frame
`h`	x Name of df column indicating photon height
`x`	Name of df column indicating photon x coordinate
`y`	Name of df column indicating photon y coordinate
`dh`	min and max height thresholds used to flag unsual photons height
`dx`	min and max horizontal distance

Segments with continuous ground points are first identified and interpolation is performaed at these segment level. THe continuity between ground point is determined by the gap_dist threshold: if two groudn points are more than gap_dist along-distance apart, a gap is detected and ground surface will be interpolated for each gap. Additionally, segments with less than min_ph_gap photons in them are discarded. Therefore, not all photons in the original df are guaranteed to be normalized.

mqueinnec/icesat2R documentation built on Feb. 18, 2022, 2:38 a.m.