Filters are strings used in the filter argument of lasR stages to process only the points of
interest. Filters follow the format 'Attribute condition value(s)', e.g.: Z > 2, Intensity < 155,
Classification == 2, or ReturnNumber == 1.
The available conditions include >, <, >=, <=, ==, !=, %in%, %out%, and %between%.
The supported attributes are any names of the attributes of the point cloud such as X, Y, Z, Intensity,
gpstime, UserData, ReturnNumber, ScanAngle, Amplitude and so on.
Note that filters never fail. If a filter references an attribute not present in the point cloud
(e.g., Intensity < 50 in a point cloud without intensity data), the attribute is treated as if it
has a value of 0. This behavior can impact conditions like Intensity < 50.
For convenience, the most commonly used filters have corresponding helper functions that return
the appropriate filter string. Points that satisfy the specified condition are retained for
processing, while others are ignored for the current stage.
Usage
keep_class(x)
drop_class(x)
keep_first()
drop_first()
keep_ground()
keep_ground_and_water()
drop_ground()
keep_noise()
drop_noise()
keep_z_above(x)
drop_z_above(x)
keep_z_below(x)
drop_z_below(x)
drop_duplicates()
# S3 method for class 'laslibfilter'
print(x, ...)
# S3 method for class 'laslibfilter'
e1 + e2Examples
f <- system.file("extdata", "Topography.las", package="lasR")
gnd = keep_class(c(2,9))
reader_las(gnd)
#> -----------
#> reader (uid:5541)
#> filter : Classification %in% 2 9
#> output :
#> -----------
triangulate(filter = keep_ground())
#> -----------
#> triangulate (uid:38ec)
#> max_edge : 0
#> filter : Classification == 2
#> output :
#> use_attribute : Z
#> -----------
rasterize(1, "max", filter = "Z > 5")
#> -----------
#> rasterize (uid:6b06)
#> res : 1
#> window : 1
#> method : max
#> filter : Z > 5
#> output : /tmp/RtmpUXX9w7/file1f161f3a8f28.tif
#> -----------