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Clip LiDAR points within a given geometry from a point cloud (LAS object) or a catalog
(LAScatalog object). With a LAS object, the user first reads and loads a point-cloud
into memory and then can clip it to get a subset within a region of interest (ROI). With a LAScatalog
object, the user can extract any arbitrary ROI for a set of las/laz files, loading only the
points of interest. This is faster, easier and much more memory-efficient for extracting ROIs.
lasclip(las, geometry, ...)lasclipRectangle(las, xleft, ybottom, xright, ytop)
lasclipPolygon(las, xpoly, ypoly)
lasclipCircle(las, xcenter, ycenter, radius)
An object of class LAS or LAScatalog.
a geometric object. Many types are supported, see section 'supported geometries'.
optional supplementary options (see supported geometries)
numeric. left x coordinates of rectangles.
numeric. bottom y coordinates of rectangles.
numeric. right x coordinates of rectangles.
numeric. top y coordinates of rectangles.
numeric. x coordinates of a polygon.
numeric. y coordinates of a polygon.
numeric. x coordinates of discs centers.
numeric. y coordinates of discs centers.
numeric. disc radius or radii.
If the input is a LAS object: an object of class LAS, or a list of LAS objects if the query
implies several regions of interest will be returned.
If the input is a LAScatalog object: an object of class LAS, or a list of LAS objects if the query
implies several regions of interest will be returned, or a LAScatalog if the queries are immediately written into files
without loading anything in R.
WKT string: describing a POINT, a POLYGON or a MULTIPOLYGON.
SpatialPoints or SpatialPointsDataFrame in that case a parameter 'radius' must be passed in '...'
SimpleFeature that consistently contains POINT or POLYGON/MULTIPOLYGON.
In case of POINT a parameter 'radius' must be passed in '...'
matrix 2 x 2 describing a bounding box following this order:
min max x 684816 684943 y 5017823 5017957
This 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: Does not make sense here.
buffer: Not supported yet.
alignment: Does not makes sense here.
cores: How many cores are used.
progress: Displays a progress estimation.
stop_early: Leave this 'as-is' unless you are an advanced user.
output_files: If 'output_files' is set in the catalog, the ROIs will not be returned in R.
They will be written immediately in files. See LAScatalog-class and examples. The allowed templates in
lasclip are {XLEFT}, {XRIGHT}, {YBOTTOM}, {YTOP}, {ID}, {XCENTER},
{YCENTER} or any names from the table of attributes of a spatial object given as
input such as {PLOT_ID} or {YEAR}, for example, if these attributes exist. If empty everything
is returned into R.
laz_compression: write las or laz files
drivers: Leave this 'as-is' unless you are an advanced user.
select: The function will write files equivalent to the originals. This option is not respected.
filter: Read only the points of interest.
# NOT RUN {
LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
# Load the file and clip the region of interest
las = readLAS(LASfile)
subset1 = lasclipRectangle(las, 684850, 5017850, 684900, 5017900)
# Do not load the file(s), extract only the region of interest from a bigger dataset
ctg = catalog(LASfile)
subset2 = lasclipRectangle(ctg, 684850, 5017850, 684900, 5017900)
# Extract all the polygons from a shapefile
shapefile_dir <- system.file("extdata", package = "lidR")
lakes = shapefile(paste0(shapefile_dir, "/lake_polygons_UTM17.shp"))
subset3 = lasclip(ctg, lakes)
# Extract the polygons, write them in files named after the lake names, do not load anything in R
opt_output_files(ctg) <- paste0(tempfile(), "_{LAKENAME_1}")
new_ctg = lasclip(ctg, lakes)
# }
# NOT RUN {
plot(subset1)
plot(subset2)
plot(subset3)
# }
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