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PROGRAM:

NAME


las2las - Advanced LAS filtering and manipulation

SYNOPSIS


las2las [OPTIONS]

DESCRIPTION


las2las reads and writes LiDAR data in the ASPRS LAS 1.0, 1.1, and 1.2 formats while
modifying its contents. las2las is designed for filtering and transformation operations
of LAS files.

While lasinfo(1), can do a few simple operations like updating header information, more
drastic changes, like removing points or altering values, will require las2las. las2las
is expected to be used for modifying single files at a time, and some las2las operations
require multiple read passes through the points. Some examples of operations las2las can
be used for include:

· clipping of points to those that lie within a certain region specified by a bounding box
(--extent)

· eliminating points that are the second return (--drop-return 2),

· eliminating points that have a scan angle above some threshold (--drop-scan-angle "<5")

· eliminating points that have an intensity below some threshold (--drop-intensity "<15")

· extracting only first (--first-only) or last (--last-only) returns

· changing the format from LAS 1.0 to 1.1 or vice versa

· eliminating points of a given classification (--eliminate class 2)

las2las started a port of Martin Isenburg's las2las utility from LASTools ⟨http://
www.cs.unc.edu/~isenburg/lastools/⟩ to the libLAS library. It is much-improved from his
version, however, and provides a number of additional capabilities.

See also. libLAS’ Relationship to LAStools ⟨http://www.liblas.org/
lastools.html#lastools-liblas⟩ contains background information on the port of Isenburg and
Shewchuck's utilities to the libLAS library.

· Text output describing the operation(s) is only provided when the --verbose (-v) switch
is provided. Errors are reported to stderr.

· Coordinate reprojection, including vertical datum transformation when compiled with the
latest GDAL ⟨http://www.gdal.org⟩ .

· Coordinate system description and alteration.

· Variable Length Records (VLRs) are carried forward by default.

· VLR alteration, including adding your own VLRs with files and removal of VLRs

· File splitting based on a specified file size (--split-mb) or points (--split-pts)

· Ability to set coordinate offsets to minimum values of the existing coordinate space.

· Color filtering

OPTIONS


las2las2 options:

-h, --help
produce help message

--split-mb arg (=0)
Split file into multiple files with each being this size in MB or less. If this
value is 0, no splitting is done

--split-pts arg (=0)
Split file into multiple files with each being this many points or less. If this
value is 0, no splitting is done

-i arg, --input arg
input LAS file

-o arg, --output arg (=output.las)
output LAS file

-v, --verbose
Verbose message output

Header modification options:

--a_srs arg
Coordinate system to assign to input LAS file

--a_vertcs arg
Override vertical coordinate system information. Use --a_vertcs "verticalCSType
[citation [verticalDatum [verticalUnits]]]" For example: --a_vertcs 5703 "North
American Vertical Datum of 1988 (NAVD88)" 5103 9001

--offset arg
A comma-separated or quoted, space-separated list of offsets to set on the output
file: --offset 0,0,0 --offset "1234 5678 91011"

--scale arg
A list of scales to set on the output file. Scales cannot be negative, and should
always be a negative power of 10: --scale 0.1 0.1 0.00001

-f arg, --file-format arg
Set the LAS format of the new file (only 1.0-1.2 supported at this time):
--file-format 1.2 -f 1.1

--point-format arg
Set the LAS point format of the new file (0, 1, 2, 3): --point-format 3

--pad-header arg
Add extra bytes to the existing header

--min-offset
Set the offset of the header to the minimums of all values in the file. Note that
this requires multiple read passes through the file to achieve.

--file-creation arg
Set the header's day/year. Specify either as "1 2010" for the first day of 2010,
or as "now" to specify the current day/year

--add-schema
Add the liblas.org schema VLR record to the file.

--delete-vlr arg
Removes VLRs with the given name and id combination. --delete-vlr LASF_Projection
34737

--add-vlr arg
Add VLRs with the given name and id combination. --add-vlr hobu 1234 "Description
of the VLR" "filename.ext"

--system-identifier arg
Set the SystemID for the file. --system-identifier "MODIFICATION"

--generating-software arg
Set the SoftwareID for the file. --generating-software "liblas.org"

Transformation options:

--t_srs arg
Coordinate system to reproject output LAS file to. Use --a_srs or verify that your
input LAS file has a coordinate system according to lasinfo

--point-translate arg
An expression to translate the X, Y, Z values of the point. For example,
converting Z units that are in meters to feet: --point-translate "x*1.0 y*1.0
z*3.2808399"

--color-source arg
A string to a GDAL-openable raster data source. Use GDAL VRTs if you want to
adjust the data source or set its coordinate system, etc. --color-source
"afile.tif"

--color-source-bands arg
A list of three bands from the --color-source to assign to the R, G, B values for
the point --color-source-bands 1 2 3

--color-source-scale arg
A number used by --color-source to scale the input R, G, B values for the point.
For example, to scale the 8 bit color data from an input raster to 16 bit, the 8
bit data should be multiplied by 257. --color-source-scale 256

Filtering options:

-e arg, --extent arg
Extent window that points must fall within to keep. Use a comma-separated or
quoted, space-separated list, for example, -e minx, miny, maxx, maxy or -e minx,
miny, minz, maxx, maxy, maxz -e "minx miny minz maxx maxy maxz"

--minx arg
Extent must be greater than or equal to minx to be kept. --minx 1234.0

--miny arg
Extent must be greater than or equal to miny to be kept. --miny 5678.0

--minz arg
Extent must be greater than or equal to minz to be kept. If maxx and maxy are set
but not minz *and maxz, all z values are kept. --minz 0.0

--maxx arg
Extent must be less than or equal to maxx to be kept. --maxx 1234.0

--maxy arg
Extent must be less than or equal to maxy to be kept. --maxy 5678.0

--maxz arg
Extent must be less than or equal to maxz to be kept. If maxx and maxy are set but
not maxz *and minz, all z values are kept. --maxz 10.0

-t arg, --thin arg (=0)
Simple decimation-style thinning. Thin the file by removing every t'th point from
the file.

--last-return-only
Keep last returns (cannot be used with --first-return-only)

--first-return-only
Keep first returns (cannot be used with --last-return-only)

--keep-returns arg
A list of return numbers to keep in the output file: --keep-returns 1 2 3

--drop-returns arg
Return numbers to drop. For example, --drop-returns 2 3 4 5

--valid_only
Keep only valid points

--keep-classes arg
A list of classifications to keep: --keep-classes 2 4 12 --keep-classes 2

--drop-classes arg
A comma-separated list of classifications to drop: --drop-classes 1,7,8
--drop-classes 2

--keep-intensity arg
Range in which to keep intensity. The following expression types are supported:
--keep-intensity 0-100 --keep-intensity <200 --keep-intensity >400 --keep-intensity
>=200

--drop-intensity arg
Range in which to drop intensity. The following expression types are supported:
--drop-intensity <200 --drop-intensity >400 --drop-intensity >=200

--keep-time arg
Range in which to keep time. The following expression types are supported:
--keep-time 413665.2336-414092.8462 --keep-time <414094.8462 --keep-time
>413665.2336 --keep-time >=413665.2336

--drop-time arg
Range in which to drop time. The following expression types are supported:
--drop-time <413666.2336 --drop-time >413665.2336 --drop-time >=413665.2336

--keep-scan-angle arg
Range in which to keep scan angle. The following expression types are supported:
--keep-scan-angle 0-100 --keep-scan-angle <100 --keep-scan-angle <=100

--drop-scan-angle arg
Range in which to drop scan angle. The following expression types are supported:
--drop-scan-angle <30 --drop-scan-angle >100 --drop-scan-angle >=100

--keep-color arg
Range in which to keep colors. Define colors as two 3-tuples (R,G,B-R,G,B):
--keep-color '0,0,0-125,125,125'

--drop-color arg
Range in which to drop colors. Define colors as two 3-tuples (R,G,B-R,G,B):
--drop-color '255,255,255-65536,65536,65536'

For more information, see the full documentation for las2las2 at:
http://liblas.org/utilities/las2las2.html

EXAMPLE


Clipping with a rectangle

$ las2las in.las --output out.las --extent "63025000 483450000 63050000 483475000"

clips points of in.las with x<=63025000 and y<=483450000 or x>=63050000 and y>=483475000
and stores surviving points to out.las.

$ las2las in.las --output out.las --extent "63025000 483450000 0 63050000 483475000 100""

clips points of in.las with x <= 63025000 and y <= 483450000 and z <= 100 or x >= 63050000
and y >= 483475000 and z >= 0

note. The quotes around the extent values are important to aid the command line parsing.
An error will likely result of not quoting the values. Alternatively, you can use commas
to separate the --extent parameters to avoid quoting.

Eliminating specified returns

$ las2las --input in.las --output out.las --drop-returns 1

eliminates all points of in.las that are designated first returns by the value in their
return_number field and stores surviving points to out.las.

$ las2las --input in.las --output out.las --drop-returns 2 3 4 5

eliminates all returns in the specified list.

Limiting based on scan angle

$ las2las --input in.las --output out.las --keep-scan-angle "<=15"

keeps all points of in.las whose scan angle is <= 15.

Limiting based on intensity

$ las2las --input in.las --output out.las --drop-intensity "<=1000"

eliminates all points of in.las whose intensity is below 1000 and stores surviving points
to out.las.

Extract last returns

$ las2las --input in.las --output out.las --last-return-only

extracts all last return points from in.las and stores them to out.las.

Throw out invalid data

$ las2las --input in.las --output out.las --valid-only

removes invalid (according to the ASPRS LAS file format specification) points. This
switch should only be required in a few special circumstances. Points that might be
invalid include those with larger-than-required scan angles.

Eliminate ground points

$ las2las --input in.las --output out.las --drop-classes 2

removes points with that have a classification of 2. Points with a classification of 2 are
conventionally called ground points, but that convention may not be followed for older LAS
1.0 files.

Eliminate ground and unclassified points

$ las2las --input in.las --output out.las --drop-classes 1 2

removes points that have a classification of 1 or 2.

Convert to 1.1

$ las2las --input in.las --output out.las --format 1.1

converts the in.las file to a 1.1-formatted file. For the most part, this conversion is
"in name only."

Alter vertical datum information

$ las2las in.las --a_vertcs 5703 "North American Vertical Datum of 1988 (NAVD88)" 5103 9001

sets the vertical datum information for the file to be NAVD88 with vertical units of
meters.

note. This may not be relevant depending upon the circumstances of the coordinate system
the file is already in. This option only changes the *description* of the points. It
does not reproject them in any way. Use a combination of --a_srs and --t_srs to do
perform reprojection of the file.

File splitting

$ las2las in.las --split-mb 10

splits the file into the required number of output-n.las files. Other filters or
operations may also be applied to the operation in combination with splitting. Each
outputted file will have its extents and point counts properly set.

$ las2las in.las --split-pts 100000

splits the file into the required number of output-n.las files with 100000 points each in
them. Other filters or operations may also be applied to the operation in combination
with splitting. Each outputted file will have its extents and point counts properly set.

note. --split-mb and --split-pts will not work exactly with --min-offset. --min-offset
will take the minimum offsets of the entire file, not each individual file that is a
result of the split.

VLR addition

$ las2las in.las --add-vlr CUSTOM_VLR 42 "A VLR description" "myfile.ext"

adds a new VLR with name CUSTOM_VLR and an ID of 42. "myfile.ext" can either be a
location to a file to read to write into the VLR, or properly escaped text that will be
inserted directly into the VLR.

warning. VLRs have a size limitation of 65536 bytes. Files that are read or escaped
arguments that are larger than 64k in size will cause an error to be thrown. Automatic
truncation will not happen.

note. If you attempt to add VLRs with an ID of 34735, 34736, or 34737, your VLR will not
be added. This is because libLAS expects to manage the GeoTIFF keys for you. You should
use the SRS handling facilities if you need to set GeoTIFF keys instead of attempting to
overwrite them directly.

VLR removal

$ las2las in.las --delete-vlr CUSTOM_VLR 42

removes all VLRs from in.las when writing the new output.las file.

Adding color from an image

It is possible to use las2las to set RGB color information from an image and set it on the
points. This requires a rewrite of the file and in some cases will require changing both
the format and point-format of the file. The following example takes the input.las file,
sets its format to 1.2, and sets the point format to 3 so it can store color information.
It also re-orders the color bands to have the 3rd band in the image be red, 1st band be
green, and second band be blue. Additionally, the color values are then multiplied by the
--color-source-scale factor or 256 to rescale the 8 bit image data to 16 bit color data.

las2las -i input.las \
--color-source image.img \
-o output.las \
--file-format 1.2 \
--point-format 3 \
--color-source-scale 256 \
--color-source-bands 3 1 2

note. If the coordinate system of image.img is not the same as the input coordinate
system of the LAS file, you should use GDAL VRTs to cause the image to be warped and
reprojected as part of the read process. See GDAL Virtual Format Tutorial ⟨http://
www.gdal.org/gdal_vrttut.html⟩ for more detail.

warning. GDAL ⟨http://www.gdal.org⟩ support must be enabled for this to work.

20 November 2015 las2las(1)

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