Classify vegetation by height

Question

Trying to further classify a las catalog that already has buildings, bridges, noise and ground classified. I want to break the unassigned points into vegetation classes by height but can't get it to work. some previous questions have used tree segmentation, I haven't run individual tree segmentation and I don't think I need to?

vegetation_class = function(Z)
{
  mz = max(Z)
  if (mz < 6)
    return(LASLOWVEGETATION)
  else if (mz >= 6 & mz <12)
    return(LASMEDIUMVEGETATION)
  else if (mz >=12 & mz <60)
    return(LASHIGHVEGETATION)
  else
    return(LASNOISE)
}

veg_ctg@data[Classification = vegetation_Class(Z)]

writeLAS(veg_ctg, "D:mypath/new1.las", index = FALSE)```


Any help is greatly appreciated.

Answer 1

This is what I'd do

library(lidR)

vegetation_class = function(mz)
{
  class = integer(length(mz))
  class[] = LASNOISE
  class[mz < 10] = LASLOWVEGETATION
  class[mz >= 10 & mz <20] = LASMEDIUMVEGETATION
  class[mz >=20 & mz <60] = LASHIGHVEGETATION
  return(class)
}

LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
las = readLAS(LASfile)

chm = rasterize_canopy(las, 2)
las = merge_spatial(las, chm, "chm")

las@data[Classification == LASUNCLASSIFIED, Classification := vegetation_class(chm)]

plot(las, color = "Classification")
plot(filter_poi(las, Classification == LASMEDIUMVEGETATION))