Copy z into extra bytes attribute

[josevim]

Hello colleagues,

I've been trying to copy z coordinate value into a new extra byte attribute:

las2las -i file.las -add_attribute 10 "temp_z" "adding Z to attribute" 0.01 -o file_addAttrib10.las

las2las -file_addAttrib10.las -copy_z_into_attribute 10 -o file_copyZtoAttrib10.las

Not sure if both instructions above should be scripted in one, but nothing happens even in two steps. Z values had also a 0.01 scale. This old post is clear on the solution but I cannot make it work:

https://groups.google.com/g/lastools/c/qhNnZu18ChQ/m/eB6AIR7_BAAJ

My LAS file has up to 9 extra bytes attributes and I'm adding a 10th one. Is that an issue?

The goal is to reserve the z coordinate for a later scaling and translation.
Link for a sample LAS file: 10003_Sample_copyZattrib10.las
Regards

[LAStools - efficient tools for LiDAR processing]

Hi,

to answer your question about the number of extra bytes: This is easy to test - we did this for you:

las2las -i lake.laz -add_attribute 10 "temp_z1" "adding Z to attribute" 0.01 -o tmp1.laz
las2las -i tmp1.laz -add_attribute 10 "temp_z2" "adding Z to attribute" 0.01 -o tmp2.laz
las2las -i tmp2.laz -add_attribute 10 "temp_z3" "adding Z to attribute" 0.01 -o tmp3.laz
las2las -i tmp3.laz -add_attribute 10 "temp_z4" "adding Z to attribute" 0.01 -o tmp4.laz
las2las -i tmp4.laz -add_attribute 10 "temp_z5" "adding Z to attribute" 0.01 -o tmp5.laz
las2las -i tmp5.laz -add_attribute 10 "temp_z6" "adding Z to attribute" 0.01 -o tmp6.laz
las2las -i tmp6.laz -add_attribute 10 "temp_z7" "adding Z to attribute" 0.01 -o tmp7.laz
las2las -i tmp7.laz -add_attribute 10 "temp_z8" "adding Z to attribute" 0.01 -o tmp8.laz
las2las -i tmp8.laz -add_attribute 10 "temp_z9" "adding Z to attribute" 0.01 -o tmp9.laz
las2las -i tmp9.laz -add_attribute 10 "temp_z10" "adding Z to attribute" 0.01 -o tmp10.laz
las2las -i tmp10.laz -add_attribute 10 "temp_z11" "adding Z to attribute" 0.01 -o tmp11.laz

We see you can add more then 10 arguments, so this is not the issue.

It looks more like your second command is just invalid: You forgot the -i argument (and we use the 64 bit version and LAZ as file format).

Try 

    las2las64 --i file_addAttrib10.laz -copy_z_into_attribute 10 -o file_copyZtoAttrib10.laz -v

It it does not work please report in detail what output the command gives you and we will try to help.

Good luck,

Jochen @rapidlasso

[josevim]

Hi Jochen,

Yes, I missed the i argument in my initial message. I tried your command(s) example and adding the attribute 10 works fine but then running,

las2las64 -i tmp1.laz -copy_z_into_attribute 10 -o tmp1_copyZ.laz -v

Does not. This is  tmp1_copyZ.laz header:

reporting all LAS header entries:
  file signature:             'LASF'
  file source ID:             10003
  global_encoding:            17
  project ID GUID data 1-4:   00000000-0000-0000-0000-000000000000
  version major.minor:        1.4
  system identifier:          'LAStools (c) by rapidlasso GmbH'
  generating software:        'las2las64 (version 250402)'
  file creation day/year:     93/2025
  header size:                375
  offset to point data:       4143
  number var. length records: 8
  point data format:          6
  point data record length:   69
  number of point records:    0
  number of points by return: 0 0 0 0 0
  scale factor x y z:         0.01 0.01 0.01
  offset x y z:               500000 2800000 0
  min x y z:                  587277.78 2870666.80 -56.55
  max x y z:                  592442.72 2871058.99 308.49
  start of waveform data packet record: 0
  start of first extended variable length record: 0
  number of extended_variable length records: 0
  extended number of point records: 11211016
  extended number of points by return: 5087964 3070747 3052305 0 0 0 0 0 0 0 0 0 0 0 0
variable length header record 1 of 8:
  reserved             0
  user ID              'LASF_Spec'
  record ID            4
  length after header  1920
  description          'by LAStools of rapidlasso GmbH'
    Extra Byte Descriptions
      data type: 4 (short), name "(pseudo-) reflectance", description: "Radiometric calibration output", scale: 0.01, offset: 0 (not set)
      data type: 1 (unsigned char), name "sigma xy", description: "XY coordinate uncertainty", scale: 0.01, offset: 0 (not set)
      data type: 1 (unsigned char), name "sigma z", description: "Z coordinate uncertainty", scale: 0.01, offset: 0 (not set)
      data type: 1 (unsigned char), name "water column optical depth", description: "Water column optical depth", scale: 0.25, offset: 0 (not set)
      data type: 1 (unsigned char), name "figure of merit", description: "FOM for bottom measurement", scale: 1 (not set), offset: 0 (not set)
      data type: 1 (unsigned char), name "Bathymetry flags", description: "Flags", scale: 1 (not set), offset: 0 (not set)
      data type: 10 (double), name "Pitch (radians)", description: "Pitch (radians)", scale: 1 (not set), offset: 0 (not set)
      data type: 10 (double), name "Roll (radians)", description: "Roll (radians)", scale: 1 (not set), offset: 0 (not set)
      data type: 10 (double), name "Heading (radians)", description: "Heading (radians)", scale: 1 (not set), offset: 0 (not set)
      data type: 10 (double), name "temp_z1", description: "adding Z to attribute", scale: 0.01, offset: 0 (not set)
variable length header record 2 of 8:
  reserved             0
  user ID              'LASF_Projection'
  record ID            34735
  length after header  40
  description          'by LAStools of rapidlasso GmbH'
    GeoKeyDirectoryTag version 1.1.0 number of keys 4
      key 1024 tiff_tag_location 0 count 1 value_offset 1 - GTModelTypeGeoKey: ModelTypeProjected
      key 3072 tiff_tag_location 0 count 1 value_offset 6346 - ProjectedCSTypeGeoKey: NAD83(2011) / UTM zone 17N
      key 3076 tiff_tag_location 0 count 1 value_offset 9001 - ProjLinearUnitsGeoKey: Linear_Meter
      key 4099 tiff_tag_location 0 count 1 value_offset 9001 - VerticalUnitsGeoKey: Linear_Meter
variable length header record 3 of 8:
  reserved             0
  user ID              'LASF_Spec'
  record ID            0
  length after header  96
  description          'Classification Lookup'
    40 Seafloor    41 Water Surface    42 Synthetic Surf.    43 Submerged Obj.    44 IHOS57 Object    45 No Bottom Found
variable length header record 4 of 8:
  reserved             0
  user ID              'LASF_Spec'
  record ID            3
  length after header  5
  description          'RPM Version'
    4.1.0
variable length header record 5 of 8:
  reserved             0
  user ID              'LASF_Spec'
  record ID            3
  length after header  559
  description          'RPM CLI Arguments'
    rpm.exe  --boresight -0.3177 0.9502 -0.9763 --depth-bias 0.05625 --glare --show-aircraft --show-derived-water --vertical-shift-tolerance 1 --shift-data --bf 0 --sbet-offset 0
variable length header record 6 of 8:
  reserved             0
  user ID              'LASF_Spec'
  record ID            3
  length after header  16
  description          'Depth Bias Model Coefficients'
    Slope: 0.05625

variable length header record 7 of 8:
  reserved             0
  user ID              'LASF_Spec'
  record ID            3
  length after header  70
  description          'Model information'
    Version: 6.0.0
Description: ramms-mvit-50-triplet-v6-model-rpi-1094

variable length header record 8 of 8:
  reserved             0
  user ID              'LASF_Projection'
  record ID            2112
  length after header  630
  description          'by LAStools of rapidlasso GmbH'
    WKT OGC COORDINATE SYSTEM:
    PROJCS["NAD83(2011) / NAD83(2011) / UTM zone 17N",GEOGCS["NAD83(2011)",DATUM["NAD_1983_2011",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","1116"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","6318"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-81],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","6346"]]
LASzip compression (version 3.4r4 c3 50000): POINT14 3 BYTE14 3
reporting minimum and maximum for all LAS point record entries ...
  X             8727778    9244272
  Y             7066680    7105899
  Z               -5655      30849
  intensity           0      65535
  return_number       1          3
  number_of_returns   1          3
  edge_of_flight_line 0          1
  scan_direction_flag 0          0
  classification      0          7
  scan_angle_rank   -26         26
  user_data           1        100
  point_source_ID 10003      10003
  gps_time 372077587.701670 372077683.749338
  extended_return_number          1      3
  extended_number_of_returns      1      3
  extended_classification         2    100
  extended_scan_angle         -4413   4407
  extended_scanner_channel        0      2
  attribute0          0          0  ('(pseudo-) reflectance')
  attribute1          0          0  ('sigma xy')
  attribute2          0          0  ('sigma z')
  attribute3          0          0  ('water column optical depth')
  attribute4          0          0  ('figure of merit')
  attribute5          0          0  ('Bathymetry flags')
  attribute6  -0.121401 0.00724537  ('Pitch (radians)')
  attribute7 -0.0371566  0.0977106  ('Roll (radians)')
  attribute8          0    1.69472  ('Heading (radians)')
  attribute9          0          0  ('temp_z1') \\----------------------------->Z range expected here!
number of first returns:        5087964
number of intermediate returns: 3052305
number of last returns:         5087707
number of single returns:       2016960
overview over extended number of returns of given pulse: 2016960 37141 9156915 0 0 0 0 0 0 0 0 0 0 0 0
histogram of classification of points:
          934215  ground (2)
           29797  noise (7)
 +-> flagged as synthetic: 5764
  +--->            5764  of those are classification (100)
histogram of extended classification of points:
         3066978  extended classification (40)
         4107284  extended classification (41)
         3066978  extended classification (42)
            5764  extended classification (100)

It still does not appear z is copied over. Would you give it a try yourself. If you want a sample file, a link is posted on the original post.

Best Regards

José

[LAStools - efficient tools for LiDAR processing]

Hi José,

please always tell the exact commands you are running and give the full verbose output.

Please see this example how we would like to see a problem report.

We tested once again: Is is working, please check again the workflow you are doing.

Starting with the file you supplied:

    lasinfo64 -i 10003_Sample_copyZattrib10.las -v

gives as output:

LAStools lasinfo (by in...@rapidlasso.de) version 250426
reading '10003_Sample_copyZattrib10.las' with 142927 points
lasinfo (250426) report for '10003_Sample_copyZattrib10.las'

reporting all LAS header entries:

... only WE are allowed to suppress some lines :)

variable length header record 1 of 8:

...

reporting minimum and maximum for all LAS point record entries ...

  X             8727778    8843057
  Y             7068579    7103337
  Z               -3220      -2761
...

  extended_scanner_channel        1      2

  attribute0          0          0  ('(pseudo-) reflectance')
  attribute1          0          0  ('sigma xy')
  attribute2          0          0  ('sigma z')
  attribute3          0          0  ('water column optical depth')
  attribute4          0          0  ('figure of merit')
  attribute5          0          0  ('Bathymetry flags')

  attribute6          0          0  ('Pitch (radians)')
  attribute7          0          0  ('Roll (radians)')
  attribute8          0          0  ('Heading (radians)')
  attribute9          0          0  ('temp_z')
number of first returns:        140163
number of intermediate returns: 0
number of last returns:         141975
number of single returns:       139211
overview over extended number of returns of given pulse: 139211 2917 799 0 0 0 0 0 0 0 0 0 0 0 0

histogram of classification of points:

          142927  ground (2)

So your 'temp_z' attribute is already there - just to show it works we add another 10th attribute/extra_byte:

    las2las64 -i  10003_Sample_copyZattrib10.las -o tmp1.laz -add_attribute 10 "temp_zz" "adding Z to attribute" 0.01 -v

We check if the field was added:

    lasinfo64 -i tmp1.laz -v

LAStools lasinfo (by in...@rapidlasso.de) version 250426
....

  attribute8          0          0  ('Heading (radians)')
  attribute9          0          0  ('temp_z')
  attribute10          0          0  ('temp_zz')
number of first returns:        140163
number of intermediate returns: 0
number of last returns:         141975
number of single returns:       139211
overview over extended number of returns of given pulse: 139211 2917 799 0 0 0 0 0 0 0 0 0 0 0 0

histogram of classification of points:

          142927  ground (2)

We see: The extra field was added as attribute10 but has no values set (value range 0...0).

Now we add the z values to this attribute:

    las2las64 -i tmp1.laz -copy_z_into_attribute 10 -o tmp1_copyZ.laz -v

LAStools las2las (by in...@rapidlasso.de) version 250426
reading 142927 and writing all surviving points ...
total time: 0.142 sec. written 142927 surviving points to 'tmp1_copyZ.laz'.

And we check the result again:

   lasinfo64 -i tmp1_copyZ.laz -v

LAStools lasinfo (by in...@rapidlasso.de) version 250426
...

  min x y z:                  587277.78 2870685.79 -32.20
  max x y z:                  588430.57 2871033.37 -27.61
...

  attribute7          0          0  ('Roll (radians)')
  attribute8          0          0  ('Heading (radians)')
  attribute9          0          0  ('temp_z')
  attribute10      -32.2     -27.61  ('temp_zz')
number of first returns:        140163
...

We see: The attribute10 is set with a value range equal to our z-range out of the header.

Everything works correct.

Please check again and report.

Cheers,

Jochen @rapidlasso

[josevim]

Thanks Jochen for the detailed explanation. I got the instruction working as desired.

I was trying to copy z to attribute "10" but the latter didn't exist. I used:

las2las64 -i 10003_Sample_copyZattrib10.las -add_attribute 10 "temp_z1" "adding Z to attribute" 0.01 -o tmp1.laz -v

But I just noticed attribute "10" was added as "9" because, either numeration starts at 0 or because the next available attribute is "9", not "10"

  attribute0          0          0  ('(pseudo-) reflectance')

  attribute1          0          0  ('sigma xy')
  attribute2          0          0  ('sigma z')
  attribute3          0          0  ('water column optical depth')
  attribute4          0          0  ('figure of merit')
  attribute5          0          0  ('Bathymetry flags')
  attribute6          0          0  ('Pitch (radians)')
  attribute7          0          0  ('Roll (radians)')
  attribute8          0          0  ('Heading (radians)')

  attribute9          0          0  ('temp_z1')

My mistake was I kept trying to add to Attribute10 when Attribute9 was needed. Then of course:

las2las64 -i  tmp1.laz  -copy_z_into_attribute 9 -o  tmp2.laz  -v

Works well:

 attribute0          0          0  ('(pseudo-) reflectance')
  attribute1          0          0  ('sigma xy')
  attribute2          0          0  ('sigma z')
  attribute3          0          0  ('water column optical depth')
  attribute4          0          0  ('figure of merit')
  attribute5          0          0  ('Bathymetry flags')
  attribute6          0          0  ('Pitch (radians)')
  attribute7          0          0  ('Roll (radians)')
  attribute8          0          0  ('Heading (radians)')

  attribute9      -26.7     -25.97  ('temp_z1')

I appreciate the prompt response and helping me to clarify the mix up.

Best Regards

josé

[LAStools - efficient tools for LiDAR processing]

Hi José,

thanks for the feedback, glad you solved the issue!

Jochen @rapidlasso