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I have a lidar dataset from which I am trying to extract a DSM and a DTM (in meters) from it for EPSG 32614 (WGS84). Below info:

lasinfo (220926) report for 'C:\LAStools\bin\Data\Cornfield Non\Backup 5\Raw\cloud92e02583c4eed578.las'
reporting all LAS header entries:
  file signature:             'LASF'
  file source ID:             0
  global_encoding:            1
  project ID GUID data 1-4:   00000000-0000-0000-0000-000000000000
  version major.minor:        1.2
  system identifier:          'REpJLUwxLURlbGwtNTc1MC4='
  generating software:        'DJI TERRA 3.10.6.0'
  file creation day/year:     195/2022
  header size:                227
  offset to point data:       1677
  number var. length records: 3
  point data format:          3
  point data record length:   34
  number of point records:    85751920
  number of points by return: 84817070 911128 23722 0 0
  scale factor x y z:         0.0001 0.0001 0.0001
  offset x y z:               3194320.982963833026588 9168216.618123717606068 77.185868757605689
  min x y z:                  3193840.1478 9167933.5993 44.6628
  max x y z:                  3194801.8181 9168499.6370 109.7089
WARNING: stored resolution of min_x not compatible with x_offset and x_scale_factor: 3193840.147787707392126
WARNING: stored resolution of min_y not compatible with y_offset and y_scale_factor: 9167933.599270919337869
WARNING: stored resolution of min_z not compatible with z_offset and z_scale_factor: 44.662826671902295
WARNING: stored resolution of max_x not compatible with x_offset and x_scale_factor: 3194801.81813995866105
WARNING: stored resolution of max_y not compatible with y_offset and y_scale_factor: 9168499.636976515874267
WARNING: stored resolution of max_z not compatible with z_offset and z_scale_factor: 109.708910843309084
variable length header record 1 of 3:
  reserved             43707
  user ID              'LASF_Projection'
  record ID            34735
  length after header  96
  description          'GeoTIFF GeoKeyDirectoryTag'
    GeoKeyDirectoryTag version 1.1.0 number of keys 11
      key 1024 tiff_tag_location 0 count 1 value_offset 1 - GTModelTypeGeoKey: ModelTypeProjected
      key 1025 tiff_tag_location 0 count 1 value_offset 1 - GTRasterTypeGeoKey: RasterPixelIsArea
      key 1026 tiff_tag_location 34737 count 58 value_offset 0 - GTCitationGeoKey: NAD83(2011) / Texas Central (ftUS) + NAVD88 height (ftUS)
      key 2049 tiff_tag_location 34737 count 12 value_offset 58 - GeogCitationGeoKey: NAD83(2011)
      key 2054 tiff_tag_location 0 count 1 value_offset 9102 - GeogAngularUnitsGeoKey: Angular_Degree
      key 3072 tiff_tag_location 0 count 1 value_offset 6578 - ProjectedCSTypeGeoKey: NAD83(2011) / Texas Central (ftUS)
      key 3076 tiff_tag_location 0 count 1 value_offset 9003 - ProjLinearUnitsGeoKey: Linear_Foot_US_Survey
      key 4096 tiff_tag_location 0 count 1 value_offset 6360 - VerticalCSTypeGeoKey: NAVD88 height (ftUS)
      key 4097 tiff_tag_location 34737 count 21 value_offset 70 - VerticalCitationGeoKey: NAVD88 height (ftUS)
      key 4098 tiff_tag_location 0 count 1 value_offset 5103 - VerticalDatumGeoKey: Vertical Datum Codes 5103
      key 4099 tiff_tag_location 0 count 1 value_offset 9003 - VerticalUnitsGeoKey: Linear_Foot_US_Survey
variable length header record 2 of 3:
  reserved             43707
  user ID              'LASF_Projection'
  record ID            34737
  length after header  92
  description          'GeoTIFF GeoAsciiParamsTag'
    GeoAsciiParamsTag (number of characters 92)
      NAD83(2011) / Texas Central (ftUS) + NAVD88 height (ftUS)|NAD83(2011)|NAVD88 height (ftUS)| 
variable length header record 3 of 3:
  reserved             43707
  user ID              'liblas'
  record ID            2112
  length after header  1100
  description          'OGR variant of OpenGIS WKT SRS'
reporting minimum and maximum for all LAS point record entries ...
  X            -4808352    4808352
  Y            -2830189    2830189
  Z             -325230     325230
  intensity           0        255
  return_number       1          3
  number_of_returns   1          3
  edge_of_flight_line 0          0
  scan_direction_flag 0          0
  classification      0          0
  scan_angle_rank   -35         35
  user_data           0          0
  point_source_ID     0          0
  gps_time 341930759.933908 341931289.757861
  Color R 0 65280
        G 0 65280
        B 0 65280
WARNING: 2 points outside of header bounding box
number of first returns:        84817070
number of intermediate returns: 23690
number of last returns:         84817572
number of single returns:       83906412
overview over number of returns of given pulse: 83906412 1774379 71129 0 0 0 0
histogram of classification of points:
        85751920  never classified (0)
WARNING: real max y larger than header max y by 0.000047
WARNING: real min y smaller than header min y by 0.000047

I am using the following workflow (tools):

  • las2las (to modify scaling factors and offset factor)
  • lasplit (to split dataset)
  • lasground (to classify dataset) using -feet -elevation_feet
  • las2las (to remove either ground points or non-ground points)
  • lasnoise (to remove noise) using -feet -elevation_feet
  • las2dem (to convert to tif & reproject)

Currently I am doing the reprojection in the last step of the workflow, but this seems not to be correct. QGIS does not overlap this reprojection with similar files I know they are in EPSG 32614.

1 Answer 1

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I had never before used lastools to reproject, so I was going by This when I said las2las wouldn't re-project. But I tried just now to use las2las to re-project a EPSG:6578 NAD83(2011)/Texas Central(ftUS) laz file to EPSG:32614 WGS84/UTM zone14N(Meters). It landed where it was supposed to. That said, I do not know if it handled the NAD83(2011) to WGS84 Datum shift correctly. To use lasdatum requires either an NTv2 grid file or seven parameter helmert transform parameters, neither of which I know where to find.

I used this command:

las2las -cpu64 -i "D:\Download\Liberty Hill\stratmap21-50cm_3097173d3.laz" -target_utm 14N -target_precision 0.01 -odir "D:\Download\Liberty Hill" -odix "_32614" -olaz

For best advice you might want to post in the LAStools Forum.

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  • I have the license, that is not a problem. Your answer will be accepted if you mention when it should be converted (beginning of workflow, end of workflow?). Giving the command would also be helpful. Oct 29, 2022 at 21:44

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