| classify_ground {lidR} | R Documentation |
Classify points as 'ground' with several possible algorithms. The function updates the
attribute Classification of the LAS object. The points classified as 'ground' are assigned
a value of 2 according to las specifications.
classify_ground(las, algorithm, last_returns = TRUE)
las |
An object of class LAS or LAScatalog. |
algorithm |
a ground-segmentation function. |
last_returns |
logical. The algorithm will use only the last returns (including the first returns
in cases of a single return) to run the algorithm. If FALSE all the returns are used. If the attribute
|
If the input is a LAS object, return a LAS object. If the input is a
LAScatalog, returns a LAScatalog.
LAScatalogThis section appears in each function that supports a LAScatalog as input.
In lidR when the input of a function is a LAScatalog the
function uses the LAScatalog processing engine. The user can modify the engine options using
the available options. A careful reading of the
engine documentation is recommended before processing LAScatalogs. Each
lidR function should come with a section that documents the supported engine options.
The LAScatalog engine supports .lax files that significantly improve the computation
speed of spatial queries using a spatial index. Users should really take advantage a .lax files,
but this is not mandatory.
Supported processing options for a LAScatalog (in bold). For more details see the
LAScatalog engine documentation:
chunk size: How much data is loaded at once.
chunk buffer*: Mandatory to get a continuous output without edge effects. The buffer is always removed once processed and will never be returned either in R or in files.
chunk alignment: Align the processed chunks.
progress: Displays a progression estimation.
output files*: Mandatory because the output is likely to be too big to be returned
in R and needs to be written in las/laz files. Supported templates are {XLEFT}, {XRIGHT},
{YBOTTOM}, {YTOP}, {XCENTER}, {YCENTER} {ID} and, if
chunk size is equal to 0 (processing by file), {ORIGINALFILENAME}.
select: The function will write files equivalent to the original ones. Thus select = "*"
and cannot be changed.
filter: Read only points of interest.
LASfile <- system.file("extdata", "Topography.laz", package="lidR")
las <- readLAS(LASfile, select = "xyzrn", filter = "-inside 273450 5274350 273550 5274450")
# Using the Progressive Morphological Filter
# --------------------------------------
# (Parameters chosen mainly for speed)
ws <- seq(3,12, 4)
th <- seq(0.1, 1.5, length.out = length(ws))
las <- classify_ground(las, pmf(ws, th))
#plot(las, color = "Classification")
#' # Using the Cloth Simulation Filter
# --------------------------------------
# (Parameters chosen mainly for speed)
mycsf <- csf(TRUE, 1, 1, time_step = 1)
las <- classify_ground(las, mycsf)
#plot(las, color = "Classification")