lasR uses LASlib/LASzip, the library developed by Martin Isenburg to read and write LAS/LAZ files.
Thus, the flags that are available in LAStools are also available in lasR.
Filters are strings to put in the filter arguments of the lasR algorithms. The list of available
strings is accessible with filter_usage. For convenience, the most useful filters have an associated
function that returns the corresponding string.
Usage
keep_class(x)
drop_class(x)
keep_first()
drop_first()
keep_ground()
drop_ground()
keep_noise()
drop_noise()
keep_z_above(x)
drop_z_above(x)
keep_z_below(x)
drop_z_below(x)
drop_duplicates()
filter_usage()
# S3 method for laslibfilter
print(x, ...)
# S3 method for laslibfilter
+(e1, e2)Examples
f <- system.file("extdata", "Topography.las", package="lasR")
filter_usage()
#> Filter points based on their coordinates.
#> -keep_tile 631000 4834000 1000 (ll_x ll_y size)
#> -keep_circle 630250.00 4834750.00 100 (x y radius)
#> -keep_xy 630000 4834000 631000 4836000 (min_x min_y max_x max_y)
#> -drop_xy 630000 4834000 631000 4836000 (min_x min_y max_x max_y)
#> -keep_x 631500.50 631501.00 (min_x max_x)
#> -drop_x 631500.50 631501.00 (min_x max_x)
#> -drop_x_below 630000.50 (min_x)
#> -drop_x_above 630500.50 (max_x)
#> -keep_y 4834500.25 4834550.25 (min_y max_y)
#> -drop_y 4834500.25 4834550.25 (min_y max_y)
#> -drop_y_below 4834500.25 (min_y)
#> -drop_y_above 4836000.75 (max_y)
#> -keep_z 11.125 130.725 (min_z max_z)
#> -drop_z 11.125 130.725 (min_z max_z)
#> -drop_z_below 11.125 (min_z)
#> -drop_z_above 130.725 (max_z)
#> -keep_xyz 620000 4830000 100 621000 4831000 200 (min_x min_y min_z max_x max_y max_z)
#> -drop_xyz 620000 4830000 100 621000 4831000 200 (min_x min_y min_z max_x max_y max_z)
#> -drop_duplicates
#> Filter points based on their return numbering.
#> -keep_first -first_only -drop_first
#> -keep_last -last_only -drop_last
#> -keep_second_last -drop_second_last
#> -keep_first_of_many -keep_last_of_many
#> -drop_first_of_many -drop_last_of_many
#> -keep_middle -drop_middle
#> -keep_return 1 2 3
#> -drop_return 3 4
#> -keep_single -drop_single
#> -keep_double -drop_double
#> -keep_triple -drop_triple
#> -keep_quadruple -drop_quadruple
#> -keep_number_of_returns 5
#> -drop_number_of_returns 0
#> Filter points based on the scanline flags.
#> -drop_scan_direction 0
#> -keep_scan_direction_change
#> -keep_edge_of_flight_line
#> Filter points based on their intensity.
#> -keep_intensity 20 380
#> -drop_intensity_below 20
#> -drop_intensity_above 380
#> -drop_intensity_between 4000 5000
#> Filter points based on classifications or flags.
#> -keep_class 1 3 7
#> -drop_class 4 2
#> -keep_extended_class 43
#> -drop_extended_class 129 135
#> -drop_synthetic -keep_synthetic
#> -drop_keypoint -keep_keypoint
#> -drop_withheld -keep_withheld
#> -drop_overlap -keep_overlap
#> Filter points based on their user data.
#> -keep_user_data 1
#> -drop_user_data 255
#> -keep_user_data_below 50
#> -keep_user_data_above 150
#> -keep_user_data_between 10 20
#> -drop_user_data_below 1
#> -drop_user_data_above 100
#> -drop_user_data_between 10 40
#> Filter points based on their point source ID.
#> -keep_point_source 3
#> -keep_point_source_between 2 6
#> -drop_point_source 27
#> -drop_point_source_below 6
#> -drop_point_source_above 15
#> -drop_point_source_between 17 21
#> Filter points based on their scan angle.
#> -keep_scan_angle -15 15
#> -drop_abs_scan_angle_above 15
#> -drop_abs_scan_angle_below 1
#> -drop_scan_angle_below -15
#> -drop_scan_angle_above 15
#> -drop_scan_angle_between -25 -23
#> Filter points based on their gps time.
#> -keep_gps_time 11.125 130.725
#> -drop_gps_time_below 11.125
#> -drop_gps_time_above 130.725
#> -drop_gps_time_between 22.0 48.0
#> Filter points based on their RGB/CIR/NIR channels.
#> -keep_RGB_red 1 1
#> -drop_RGB_red 5000 20000
#> -keep_RGB_green 30 100
#> -drop_RGB_green 2000 10000
#> -keep_RGB_blue 0 0
#> -keep_RGB_nir 64 127
#> -keep_RGB_greenness 200 65535
#> -keep_NDVI 0.2 0.7 -keep_NDVI_from_CIR -0.1 0.5
#> -keep_NDVI_intensity_is_NIR 0.4 0.8 -keep_NDVI_green_is_NIR -0.2 0.2
#> Filter points based on their wavepacket.
#> -keep_wavepacket 0
#> -drop_wavepacket 3
#> Filter points based on extra attributes.
#> -keep_attribute_above 0 5.0
#> -drop_attribute_below 1 1.5
#> Filter points with simple thinning.
#> -keep_every_nth 2 -drop_every_nth 3
#> -keep_random_fraction 0.1
#> -keep_random_fraction 0.1 4711
#> -thin_with_grid 1.0
#> -thin_pulses_with_time 0.0001
#> -thin_points_with_time 0.000001
#> Boolean combination of filters.
#> -filter_and
gnd = keep_class(c(2,9))
reader(f, gnd)
#> Warning: reader() is deprecated(). Use reader_las().
#> -----------
#> reader_las (uid:cgWfAl)
#> files : Topography.las
#> filter : -keep_class 2 9
#> buffer : 0
#> output :
#> -----------
triangulate(filter = keep_ground())
#> -----------
#> triangulate (uid:MkPN1W)
#> max_edge : 0
#> filter : -keep_class 2
#> output :
#> use_attribute : Z
#> -----------
rasterize(1, "max", filter = "-drop_z_below 5")
#> -----------
#> rasterize (uid:RZorR1)
#> res : 1
#> window : 1
#> method : max
#> filter : -drop_z_below 5
#> output : /tmp/RtmpI3nt3B/file1f7b15ed0d5c.tif
#> -----------