CONCATENATION OF LAS (or LAZ) FILES INTO ONE FILE

[D-man]

Hello,

I've got a bunch of small LAS tile files that I'd like to concatenate and process them as one file later on.

I had a look in the readme file but it's not entirely clear how to do this.

Can anyone provide an example of how to do this properly?

Cheers,

Stu

[Martin Isenburg]

Hello,

here an example. First we turn the venerable 'fusa.laz' file into a number of smaller files of 25000 points each using lasmerge with the '-split 25000' option:

lasmerge -v -i  ..\data\fusa.laz ^

                -split 25000 ^

                -o fusa_part0000.laz

merging headers took 0 sec. there are 277573 points in total.

splitting file 'fusa_part0000.laz' took 0.078 sec.

splitting file 'fusa_part0001.laz' took 0.078 sec.

splitting file 'fusa_part0002.laz' took 0.103 sec.

splitting file 'fusa_part0003.laz' took 0.081 sec.

splitting file 'fusa_part0004.laz' took 0.093 sec.

splitting file 'fusa_part0005.laz' took 0.063 sec.

splitting file 'fusa_part0006.laz' took 0.062 sec.

splitting file 'fusa_part0007.laz' took 0.081 sec.

splitting file 'fusa_part0008.laz' took 0.062 sec.

splitting file 'fusa_part0009.laz' took 0.062 sec.

splitting file 'fusa_part0010.laz' took 0.068 sec.

splitting file 'fusa_part0011.laz' took 0.015 sec.

Here are the resulting files:

dir fusa_part*.laz

02/04/2019  01:14 PM            89,259 fusa_part0000.laz

02/04/2019  01:14 PM            95,405 fusa_part0001.laz

02/04/2019  01:14 PM           106,906 fusa_part0002.laz

02/04/2019  01:14 PM           107,263 fusa_part0003.laz

02/04/2019  01:14 PM           104,879 fusa_part0004.laz

02/04/2019  01:14 PM            95,306 fusa_part0005.laz

02/04/2019  01:14 PM            96,441 fusa_part0006.laz

02/04/2019  01:14 PM           101,471 fusa_part0007.laz

02/04/2019  01:14 PM            99,295 fusa_part0008.laz

02/04/2019  01:14 PM           103,762 fusa_part0009.laz

02/04/2019  01:14 PM            96,483 fusa_part0010.laz

02/04/2019  01:14 PM             8,748 fusa_part0011.laz

              12 Datei(en),      1,105,218 Bytes

Now we merge them back together:

lasmerge -v -i fusa_part*.laz ^

               -o fusa_merged.laz

merging headers took 0.015 sec. there are 277573 points in total.

merging files took 0.868 sec.

Here is the merged result:

dir fusa_merged.laz

02/04/2019  01:16 PM         1,078,962 fusa_merged.laz

               1 Datei(en),      1,078,962 Bytes

lasview -i fusa_merged.laz

lasinfo -i fusa_merged.laz

lasinfo (190127) report for 'fusa_merged.laz'

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             0

  global_encoding:            0

  project ID GUID data 1-4:   00000000-0000-0000-0000-000000000000

  version major.minor:        1.1

  system identifier:          'LAStools (c) by rapidlasso GmbH'

  generating software:        'lasmerge (version 190127)'

  file creation day/year:     40/2010

  header size:                227

  offset to point data:       321

  number var. length records: 1

  point data format:          1

  point data record length:   28

  number of point records:    277573

  number of points by return: 263413 13879 281 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               0 0 0

  min x y z:                  277750.00 6122250.00 42.21

  max x y z:                  277999.99 6122499.99 64.35

variable length header record 1 of 1:

  reserved             43707

  user ID              'LASF_Projection'

  record ID            34735

  length after header  40

  description          'by LAStools of Martin Isenburg'

    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 32754 - ProjectedCSTypeGeoKey: WGS 84 / UTM 54S

      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

LASzip compression (version 3.2r9 c2 50000): POINT10 2 GPSTIME11 2

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

  X            27775000   27799999

  Y           612225000  612249999

  Z                4221       6435

  intensity          10      62293

  return_number       1          3

  number_of_returns   1          3

  edge_of_flight_line 0          0

  scan_direction_flag 0          0

  classification      1          6

  scan_angle_rank    79        103

  user_data           0        197

  point_source_ID     1          1

  gps_time 5880.963028 5886.739738

number of first returns:        263413

number of intermediate returns: 283

number of last returns:         263370

number of single returns:       249493

overview over number of returns of given pulse: 249493 27232 848 0 0 0 0

histogram of classification of points:

           17553  unclassified (1)

          180868  ground (2)

           37030  high vegetation (5)

           42122  building (6)

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