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lasdiff_README.txt
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lasdiff_README.txt
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****************************************************************
this file is deprecated - see *.md version of this file
****************************************************************
lasdiff:
compares the LIDAR data of two LAS/LAZ/ASCII files and reports
whether they are identical or whether they are different.
For updates check the website or join the LAStools mailing list.
http://lastools.org/
http://groups.google.com/group/lastools/
http://twitter.com/lastools/
http://facebook.com/lastools/
http://linkedin.com/groups?gid=4408378
Martin @lastools
****************************************************************
example usage:
>>> lasdiff lidar.las lidar.laz
verifies the original LAS file and the compressed LAZ file are
identical and if not prints out differences.
>>> lasdiff -i lidar1.las -i lidar2.las -o lidar3.las
in case two LiDAR files contain the same points that are in the
same order it can be interesting to compute a possible elevation
difference that will then be stored in lidar3.las
here is an interesting example application for that using the
data from the C:\lastools\data folder that is included in the
lastools.zip distribution.
(1) first we create a digital surface model (DSM)
las2dem -i ..\data\fusa.laz -step 2 -first_only -o dsm.asc
(2) then we create a digital terrain model (DTM)
las2dem -i ..\data\fusa.laz -step 2 -keep_class 2 -o dtm.asc
(3) now we create a difference of the two
lasdiff -i dsm.asc -i dtm.asc -o nsm.las
lasdiff -i dsm.asc -i dtm.asc -o nsm.xyz
(4) if the two rasters were identical then all z coordinates
would be zero. the variation in z coordinate can be used to
derive whatever answer is of interest. in this example here
the variation in z coordinate represents a normalized surface
model (NSM).
for more info:
D:\lastools\bin>lasdiff -h
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)
Filter points based on their return number.
-first_only -keep_first -drop_first
-last_only -keep_last -drop_last
-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_quintuple -drop_quintuple
Filter points based on the scanline flags.
-drop_scan_direction 0
-scan_direction_change_only
-edge_of_flight_line_only
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 their classification.
-keep_class 1 3 7
-drop_class 4 2
-drop_synthetic -keep_synthetic
-drop_keypoint -keep_keypoint
-drop_withheld -keep_withheld
Filter points based on their user data.
-keep_user_data 1
-drop_user_data 255
-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_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 wavepacket.
-keep_wavepacket 0
-drop_wavepacket 3
Filter points with simple thinning.
-keep_every_nth 2
-keep_random_fraction 0.1
-thin_with_grid 1.0
Transform coordinates.
-translate_x -2.5
-scale_z 0.3048
-rotate_xy 15.0 620000 4100000 (angle + origin)
-translate_xyz 0.5 0.5 0
-translate_then_scale_y -0.5 1.001
-clamp_z_below 70.5
-clamp_z 70.5 72.5
Transform raw xyz integers.
-translate_raw_z 20
-translate_raw_xyz 1 1 0
-clamp_raw_z 500 800
Transform intensity.
-scale_intensity 2.5
-translate_intensity 50
-translate_then_scale_intensity 0.5 3.1
-clamp_intensity 0 255
-clamp_intensity_above 255
Transform scan_angle.
-scale_scan_angle 1.944445
-translate_scan_angle -5
-translate_then_scale_scan_angle -0.5 2.1
Change the return number or return count of points.
-repair_zero_returns
-set_return_number 1
-change_return_number_from_to 2 1
-set_number_of_returns 2
-change_number_of_returns_from_to 0 2
Modify the classification.
-set_classification 2
-change_classification_from_to 2 4
-classify_z_below_as -5.0 7
-classify_z_above_as 70.0 7
-classify_z_between_as 2.0 5.0 4
-classify_intensity_above_as 200 9
-classify_intensity_below_as 30 11
Modify the user data.
-set_user_data 0
-change_user_data_from_to 23 26
Modify the point source ID.
-set_point_source 500
-change_point_source_from_to 1023 1024
-quantize_Z_into_point_source 200
Transform gps_time.
-translate_gps_time 40.50
-adjusted_to_week
-week_to_adjusted 1671
Transform RGB colors.
-scale_rgb_down (by 256)
-scale_rgb_up (by 256)
Supported LAS Inputs
-i lidar.las
-i lidar.laz
-i lidar1.las lidar2.las lidar3.las -merged
-i *.las - merged
-i flight0??.laz flight1??.laz
-i terrasolid.bin
-i esri.shp
-i nasa.qi
-i lidar.txt -iparse xyzti -iskip 2 (on-the-fly from ASCII)
-i lidar.txt -iparse xyzi -itranslate_intensity 1024
-lof file_list.txt
-stdin (pipe from stdin)
-rescale 0.01 0.01 0.001
-rescale_xy 0.01 0.01
-rescale_z 0.01
-reoffset 600000 4000000 0
Supported LAS Outputs
-o lidar.las
-o lidar.laz
-o xyzta.txt -oparse xyzta (on-the-fly to ASCII)
-o terrasolid.bin
-o nasa.qi
-odir C:\data\ground (specify output directory)
-odix _classified (specify file name appendix)
-ocut 2 (cut the last two characters from name)
-olas -olaz -otxt -obin -oqfit (specify format)
-stdout (pipe to stdout)
-nil (pipe to NULL)
LAStools (by info@rapidlasso.de) version 140301
usage:
lasdiff lidar.las
lasdiff lidar1.las lidar1.laz
lasdiff *.las
lasdiff lidar1.las lidar2.las -shutup 20
lasdiff lidar1.txt lidar2.txt -iparse xyzti
lasdiff lidar1.las lidar1.laz
lasdiff lidar1.las lidar1.laz -random_seeks
lasdiff -i lidar1.las -i lidar2.las -o diff.las
lasdiff -h
---------------
if you find bugs let me (info@rapidlasso.de) know.