Incorrect geo information for EPSG:27700

[Nicholas Pilkington]

las2las.exe -i {pointcloud}.las -o tmp.laz -epsg 4326 -target_epsg 27700 -target_utm auto -target_meter -target_elevation_meter

And subsequently converting to a TIFF give a TIF with the following meta information:

PROJCS["OSGB 1936 / British National Grid",

    GEOGCS["Unknown datum based upon the Airy 1830 ellipsoid",

        DATUM["OSGB_1936",

            SPHEROID["Airy 1830",6377563.396,299.3249646000043,

                AUTHORITY["EPSG","7001"]],

            AUTHORITY["EPSG","6277"]],

        PRIMEM["Greenwich",0],

        UNIT["degree",0.0174532925199433],

        AUTHORITY["EPSG","4001"]],

    PROJECTION["Transverse_Mercator"],

    PARAMETER["latitude_of_origin",49],

    PARAMETER["central_meridian",-2],

    PARAMETER["scale_factor",0.9996012717],

    PARAMETER["false_easting",400000],

    PARAMETER["false_northing",-100000],

    UNIT["metre",1,

        AUTHORITY["EPSG","9001"]],

    AUTHORITY["EPSG","27700"]]

Instead of

```PROJCS["OSGB 1936 / British National Grid",

    GEOGCS["OSGB 1936",

        DATUM["OSGB_1936",

            SPHEROID["Airy 1830",6377563.396,299.3249646,

                AUTHORITY["EPSG","7001"]],

            TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],

            AUTHORITY["EPSG","6277"]],

        PRIMEM["Greenwich",0,

            AUTHORITY["EPSG","8901"]],

        UNIT["degree",0.0174532925199433,

            AUTHORITY["EPSG","9122"]],

        AUTHORITY["EPSG","4277"]],

    PROJECTION["Transverse_Mercator"],

    PARAMETER["latitude_of_origin",49],

    PARAMETER["central_meridian",-2],

    PARAMETER["scale_factor",0.9996012717],

    PARAMETER["false_easting",400000],

    PARAMETER["false_northing",-100000],

    UNIT["metre",1,

        AUTHORITY["EPSG","9001"]],

    AXIS["Easting",EAST],

    AXIS["Northing",NORTH],

    AUTHORITY["EPSG","27700"]]```

[Martin Isenburg]

Hello,

could you provide lasinfo reports before and after (or simply a link to a small test file that is like the input you use)?

But maybe the issue is simply that you are overriding the target EPSG of 27700 by also specifying the target as UTM. Hence you end up with a UTM projection and - I think - as your DATUM in the source LAS file seems to be based on the Airy 1830 and there is not Airy 1830 UTM definition you get a weird mix. Try simply removing ' -target_utm auto' from your command line as you should not use both -target_epsg 27700 and -target_utm auto but only one of them. I'll add a safety check to las2las in the next release that will prevent that.

las2las.exe -i {pointcloud}.las -o tmp.laz -epsg 4326 -target_epsg 27700 -target_meter -target_elevation_meter 

 

Regards,

Martin @rapidlasso

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[Nicholas Pilkington]

LasInfo Before:

lasinfo (171030) report for points.las

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             1

  global_encoding:            0

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

  version major.minor:        1.2

  system identifier:          'DroneDeploy'

  generating software:        'DroneDeploy'

  file creation day/year:     265/2018

  header size:                227

  offset to point data:       540

  number var. length records: 3

  point data format:          2

  point data record length:   26

  number of point records:    50454236

  number of points by return: 50454236 0 0 0 0

  scale factor x y z:         0.0000001 0.00000001 0.001

  offset x y z:               -1.6 52.469999999999999 100

  min x y z:                  -1.5943232 52.47809889 124.816

  max x y z:                  -1.5836609 52.48798706 213.268

WARNING: full resolution of min_y not compatible with y_offset and y_scale_factor: 52.478098889999998

WARNING: full resolution of max_y not compatible with y_offset and y_scale_factor: 52.487987060000002

variable length header record 1 of 3:

  reserved             0

  user ID              'LASF_Projection'

  record ID            34735

  length after header  112

  description          ''

    GeoKeyDirectoryTag version 1.1.0 number of keys 13

      key 1024 tiff_tag_location 0 count 1 value_offset 2 - GTModelTypeGeoKey: ModelTypeGeographic

      key 1025 tiff_tag_location 0 count 1 value_offset 1 - GTRasterTypeGeoKey: RasterPixelIsArea

      key 2048 tiff_tag_location 0 count 1 value_offset 4326 - GeographicTypeGeoKey: GCS_WGS_84

      key 2049 tiff_tag_location 34737 count 7 value_offset 0 - GeogCitationGeoKey: WGS 84

      key 2050 tiff_tag_location 0 count 1 value_offset 6326 - GeogGeodeticDatumGeoKey: Datum_WGS84

      key 2051 tiff_tag_location 0 count 1 value_offset 8901 - GeogPrimeMeridianGeoKey: PM_Greenwich

      key 2054 tiff_tag_location 0 count 1 value_offset 9102 - GeogAngularUnitsGeoKey: Angular_Degree

      key 2055 tiff_tag_location 34736 count 1 value_offset 0 - GeogAngularUnitSizeGeoKey: 0.01745329252

      key 2056 tiff_tag_location 0 count 1 value_offset 7030 - GeogEllipsoidGeoKey: Ellipse_WGS_84

      key 2057 tiff_tag_location 34736 count 1 value_offset 1 - GeogSemiMajorAxisGeoKey: 6378137

      key 2059 tiff_tag_location 34736 count 1 value_offset 2 - GeogInvFlatteningGeoKey: 298.2572236

      key 2061 tiff_tag_location 34736 count 1 value_offset 3 - GeogPrimeMeridianLongGeoKey: 0

      key 4099 tiff_tag_location 0 count 1 value_offset 9001 - VerticalUnitsGeoKey: Linear_Meter

variable length header record 2 of 3:

  reserved             0

  user ID              'LASF_Projection'

  record ID            34736

  length after header  32

  description          ''

    GeoDoubleParamsTag (number of doubles 4)

      0.0174533 6.37814e+006 298.257 0 

variable length header record 3 of 3:

  reserved             0

  user ID              'LASF_Projection'

  record ID            34737

  length after header  7

  description          ''

    GeoAsciiParamsTag (number of characters 7)

      WGS 84|

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

  X               56768     163391

  Y              809889    1798706

  Z               24816     113268

  intensity        1542      65535

  return_number       1          1

  number_of_returns   1          1

  edge_of_flight_line 0          0

  scan_direction_flag 1          1

  classification      0          0

  scan_angle_rank     0          0

  user_data           0          0

  point_source_ID     1          1

  Color R 0 65535

        G 0 65535

        B 0 65535

number of first returns:        50454236

number of intermediate returns: 0

number of last returns:         50454236

number of single returns:       50454236

overview over number of returns of given pulse: 50454236 0 0 0 0 0 0

histogram of classification of points:

        50454236  never classified (0)

Conversion command: 

wine las2las.exe -i points.las -o tmp.laz -epsg 4326 -target_epsg 27700 -target_meter -target_elevation_meter

LasInfo After:

lasinfo (171030) report for tmp.laz

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             1

  global_encoding:            0

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

  version major.minor:        1.2

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

  generating software:        'las2las (version 171030)'

  file creation day/year:     265/2018

  header size:                227

  offset to point data:       321

  number var. length records: 1

  point data format:          2

  point data record length:   26

  number of point records:    50454236

  number of points by return: 50454236 0 0 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               400000 200000 0

  min x y z:                  427546.92 286806.27 124.82

  max x y z:                  428270.59 287905.59 213.27

variable length header record 1 of 1:

  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 27700 - ProjectedCSTypeGeoKey: OSGB 1936 / British National Grid

      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 3.1r0 c2 50000): POINT10 2 RGB12 2

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

  X             2754692    2827059

  Y             8680627    8790559

  Z               12482      21327

  intensity        1542      65535

  return_number       1          1

  number_of_returns   1          1

  edge_of_flight_line 0          0

  scan_direction_flag 1          1

  classification      0          0

  scan_angle_rank     0          0

  user_data           0          0

  point_source_ID     1          1

  Color R 0 65535

        G 0 65535

        B 0 65535

number of first returns:        50454236

number of intermediate returns: 0

number of last returns:         50454236

number of single returns:       50454236

overview over number of returns of given pulse: 50454236 0 0 0 0 0 0

histogram of classification of points:

        50454236  never classified (0)

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[Martin Isenburg]

Hello Nick,

unfortunately this will not give you the correct output as a *DATUM* change is not supported by las2las (unless you use a Helmert seven parameter transform). Your input coordinates seem to be geographic coordinates defined on the WGS_1984 datum. Your target coordinates are defined on the OSGB_1936 datum which is based on the "Airy 1830" ellipsoid. Currently las2las (and I should fix that) does not warn you about the fact that the datum is not being transformed properly. If you run the las2las command as shown you essentially wrongly "declare" the " WGS_1984 datum" to be the "OSGB_1936" datum and perform the long/lat to Transverse Mercator computation which should give results that are off.

The best solution is to remain on the WGS_1984 datum by convincing your customer not to go to the old British datum but rather convert other data from the old British datum to some newer Coordinate Reference System (CRS) that is also based on the WGS_1984 datum.

The other solution is to do the conversion and that is nicely described here:

https://digimap.edina.ac.uk/webhelp/digimapgis/projections_and_transformations/converting_between_osgb36_and_wgs84.htm

There are two ways:

1) Where accuracy is not essential,  a 7-parameter Helmert transformation can be used that is accurate to +/- 5 metres using the following parameters to go from WGS84 to OSGB36:

- 446.448 + 125.157 - 542.060 + 20.4894 - 0.1502 - 0.2470 - 0.8421

This can be done with LAStools as described here:

https://groups.google.com/d/msg/lastools/j_xCv9YtxO4/evB8H-fiCQAJ

2) Where accuracy is important the National Grid Transformation, OSTN02 should be used. It has an accuracy level of less than a metre.

This can be done with GDAL / OGR as described here:

https://digimap.edina.ac.uk/webhelp/digimapgis/projections_and_transformations/transformations_in_gdalogr.htm

We should add support for this in LAStools eventually (it's just really really boring and painstaking to implement and you always need to get the right grid file).

Regards,

Martin @rapidlasso

=====================================

EPSG 4326

GEOGCS["WGS 84",

    DATUM["WGS_1984",

        SPHEROID["WGS 84",6378137,298.257223563,

            AUTHORITY["EPSG","7030"]],

        AUTHORITY["EPSG","6326"]],

    PRIMEM["Greenwich",0,

        AUTHORITY["EPSG","8901"]],

    UNIT["degree",0.01745329251994328,

        AUTHORITY["EPSG","9122"]],

    AUTHORITY["EPSG","4326"]]

EPSG 27700

PROJCS["OSGB 1936 / British National Grid",

    GEOGCS["OSGB 1936",

        DATUM["OSGB_1936",

            SPHEROID["Airy 1830",6377563.396,299.3249646,

                AUTHORITY["EPSG","7001"]],

            AUTHORITY["EPSG","6277"]],

        PRIMEM["Greenwich",0,

            AUTHORITY["EPSG","8901"]],

        UNIT["degree",0.01745329251994328,

            AUTHORITY["EPSG","9122"]],

        AUTHORITY["EPSG","4277"]],

    UNIT["metre",1,

        AUTHORITY["EPSG","9001"]],

    PROJECTION["Transverse_Mercator"],

    PARAMETER["latitude_of_origin",49],

    PARAMETER["central_meridian",-2],

    PARAMETER["scale_factor",0.9996012717],

    PARAMETER["false_easting",400000],

    PARAMETER["false_northing",-100000],

    AUTHORITY["EPSG","27700"],

    AXIS["Easting",EAST],

    AXIS["Northing",NORTH]]

[Nicholas Pilkington]

I will try and Helmert Transform approach, in general where did you find the parameters for the transform between different datums?

[Martin Isenburg]

Hello Nick,

it would be great if you could share a small LAZ file (via a download link) so that I can post a complete example of how to do a datum transform with the Helmert Transform. I'm not sure where there is a complete collection of all known Helmert Transforms published. Often there is a TOWGS84 string in the CRS description that contains the 7 parameters so that "TOWGS84" is a good keyword to use in your google search for the particular  datum   transform to and from the WGS84 datum you are interested in.

Regards,

Martin 

[Nicholas Pilkington]

Here's a sample of the point cloud in .LAZ: https://www.dropbox.com/s/kw1pxau57r14ffk/points.laz?dl=0

[Martin Isenburg]

Hello,

That's a small LAZ file? 500MB? (-: Well ... it's a nice sample data set to play with. Thank you.

When data is in long/lat on the WSG84 ellipsoid (see lasinfo report of point.laz at the end) or when data is in some projection that uses the WGS 1984 datum then I tend to be happiest because it's so easy to display the data in Google Earth. That means I can quickly generate some raster for a "sanity check" of whether the data aligns horizontal to Google's earth. So let's do this first. For long/lat data you need to choose a very small step size in degrees.

:: generate RGB raster 

lasgrid -i points.laz ^

            -step 0.00001 ^

            -rgb ^

            -fill 2 ^

            -odix _rgb -opng

:: generate false color elevation raster with min max values hand-picked based on the 

:: histogram of all point elevation (see lasinfo report of point.laz at the end)

lasgrid -i points.laz ^

            -step 0.00001 ^

            -elevation -average ^

            -fill 1 ^

            -false -set_min_max 155 205 ^

            -odix _elev_155_205 -opng

The resulting images are attached.

The following command sequence converts from long/lat coordinates in WGS84 to EPSG projection 27700 in OSGB1936. Because the '-osgb1936' was just added now for convenience you should use this version of las2las to perform these steps:

https://www.dropbox.com/s/hi8p0q2q0u0meyl/las2las.exe 

:: convert to ECEF (earth-centered, earth-fixed)  WGS84

las2las -i points.laz ^

            -target_ecef ^

            -odix _ecef_wgs84 -olaz

:: convert to ECEF (earth-centered, earth-fixed)  OSGB1936

las2las -i points_ecef_wgs84.laz ^

            -transform_helmert -446.448,125.157,-542.06,-0.1502,-0.247,-0.8421,20.4894 ^

            -osgb1936 -ecef ^

            -ocut 6 -odix _osgb1936 -olaz

:: convert to EPSG 27700 

las2las -i points_ecef_osgb1936.laz ^

            -target_epsg 27700 ^

            -ocut 14 -odix _epsg27700 -olaz

The key is the correct Helmert Transformation applied to the points in an ECEF representation. I got the numbers for the transform here:

https://en.wikipedia.org/wiki/Helmert_transformation

To get the inverse Helmert Transformations one simply changes the signs on all numbers. The known transforms are also listed in the gsc.csv file that you find in the .\LAStools\bin\serf\geo folder. 

Below are all lasinfo reports for the original point.laz and all the intermediate and final files created.

=============================

C:\software\LAStools\bin>lasinfo -i points.laz -histo z 5

lasinfo (181108) report for 'points.laz'

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             1

  global_encoding:            0

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

  version major.minor:        1.2

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

  generating software:        'las2las (version 171030)'

  file creation day/year:     265/2018

  header size:                227

  offset to point data:       540

  number var. length records: 3

  point data format:          2

  point data record length:   26

  number of point records:    50454236

  number of points by return: 50454236 0 0 0 0

  scale factor x y z:         0.0000001 0.00000001 0.001

  offset x y z:               -1.6 52.469999999999999 100

  min x y z:                  -1.5943232 52.47809889 124.816

  max x y z:                  -1.5836609 52.48798706 213.268

LASzip compression (version 3.1r0 c2 50000): POINT10 2 RGB12 2

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

  X               56768     163391

  Y              809889    1798706

  Z               24816     113268

  intensity        1542      65535

  return_number       1          1

  number_of_returns   1          1

  edge_of_flight_line 0          0

  scan_direction_flag 1          1

  classification      0          0

  scan_angle_rank     0          0

  user_data           0          0

  point_source_ID     1          1

  Color R 0 65535

        G 0 65535

        B 0 65535

number of first returns:        50454236

number of intermediate returns: 0

number of last returns:         50454236

number of single returns:       50454236

overview over number of returns of given pulse: 50454236 0 0 0 0 0 0

histogram of classification of points:

        50454236  never classified (0)

z coordinate histogram with bin size 5.000000

  bin [120,125) has 4

  bin [125,130) has 111

  bin [130,135) has 36

  bin [135,140) has 114

  bin [140,145) has 394

  bin [145,150) has 983

  bin [150,155) has 2285

  bin [155,160) has 3811313

  bin [160,165) has 9758432

  bin [165,170) has 13035530

  bin [170,175) has 12361610

  bin [175,180) has 6756041

  bin [180,185) has 2726410

  bin [185,190) has 1299793

  bin [190,195) has 416096

  bin [195,200) has 204840

  bin [200,205) has 77126

  bin [205,210) has 3002

  bin [210,215) has 116

  average z coordinate 170.09930887015361 for 50454236 element(s)

C:\software\LAStools\bin>lasinfo -i points_ecef_wgs84.laz

lasinfo (181108) report for 'points_ecef_wgs84.laz'

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             1

  global_encoding:            0

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

  version major.minor:        1.2

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

  generating software:        'las2las (version 181108)'

  file creation day/year:     265/2018

  header size:                227

  offset to point data:       305

  number var. length records: 1

  point data format:          2

  point data record length:   26

  number of point records:    50454236

  number of points by return: 50454236 0 0 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               3800000 -100000 5000000

  min x y z:                  3890626.84 -108313.42 5035496.80

  max x y z:                  3891524.66 -107568.84 5036186.45

variable length header record 1 of 1:

  reserved             0

  user ID              'LASF_Projection'

  record ID            34735

  length after header  24

  description          'by LAStools of rapidlasso GmbH'

    GeoKeyDirectoryTag version 1.1.0 number of keys 2

      key 1024 tiff_tag_location 0 count 1 value_offset 3 - GTModelTypeGeoKey: ModelTypeGeocentric

      key 2048 tiff_tag_location 0 count 1 value_offset 4326 - GeographicTypeGeoKey: GCS_WGS_84

LASzip compression (version 3.2r8 c2 50000): POINT10 2 RGB12 2

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

  X             9062684    9152466

  Y             -831342    -756884

  Z             3549680    3618645

  intensity        1542      65535

  return_number       1          1

  number_of_returns   1          1

  edge_of_flight_line 0          0

  scan_direction_flag 1          1

  classification      0          0

  scan_angle_rank     0          0

  user_data           0          0

  point_source_ID     1          1

  Color R 0 65535

        G 0 65535

        B 0 65535

number of first returns:        50454236

number of intermediate returns: 0

number of last returns:         50454236

number of single returns:       50454236

overview over number of returns of given pulse: 50454236 0 0 0 0 0 0

histogram of classification of points:

        50454236  never classified (0)

C:\software\LAStools\bin>lasinfo -i points_ecef_osgb1936.laz

lasinfo (181108) report for 'points_ecef_osgb1936.laz'

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             1

  global_encoding:            0

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

  version major.minor:        1.2

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

  generating software:        'las2las (version 181108)'

  file creation day/year:     265/2018

  header size:                227

  offset to point data:       305

  number var. length records: 1

  point data format:          2

  point data record length:   26

  number of point records:    50454236

  number of points by return: 50454236 0 0 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               3800000 -100000 5000000

  min x y z:                  3890253.64 -108202.70 5035062.65

  max x y z:                  3891151.48 -107458.10 5035752.32

variable length header record 1 of 1:

  reserved             0

  user ID              'LASF_Projection'

  record ID            34735

  length after header  24

  description          'by LAStools of rapidlasso GmbH'

    GeoKeyDirectoryTag version 1.1.0 number of keys 2

      key 1024 tiff_tag_location 0 count 1 value_offset 3 - GTModelTypeGeoKey: ModelTypeGeocentric

      key 2048 tiff_tag_location 0 count 1 value_offset 4001 - GeographicTypeGeoKey: GCSE_Airy1830

LASzip compression (version 3.2r8 c2 50000): POINT10 2 RGB12 2

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

  X             9025364    9115148

  Y             -820270    -745810

  Z             3506265    3575232

  intensity        1542      65535

  return_number       1          1

  number_of_returns   1          1

  edge_of_flight_line 0          0

  scan_direction_flag 1          1

  classification      0          0

  scan_angle_rank     0          0

  user_data           0          0

  point_source_ID     1          1

  Color R 0 65535

        G 0 65535

        B 0 65535

number of first returns:        50454236

number of intermediate returns: 0

number of last returns:         50454236

number of single returns:       50454236

overview over number of returns of given pulse: 50454236 0 0 0 0 0 0

histogram of classification of points:

        50454236  never classified (0)

C:\software\LAStools\bin>lasinfo -i points_epsg27700.laz

lasinfo (181108) report for 'points_epsg27700.laz'

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             1

  global_encoding:            0

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

  version major.minor:        1.2

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

  generating software:        'las2las (version 181108)'

  file creation day/year:     265/2018

  header size:                227

  offset to point data:       321

  number var. length records: 1

  point data format:          2

  point data record length:   26

  number of point records:    50454236

  number of points by return: 50454236 0 0 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               400000 200000 0

  min x y z:                  427647.40 286765.12 75.88

  max x y z:                  428371.16 287864.57 164.34

variable length header record 1 of 1:

  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 27700 - ProjectedCSTypeGeoKey: OSGB 1936 / British National Grid

      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 3.2r8 c2 50000): POINT10 2 RGB12 2

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

  X             2764740    2837116

  Y             8676512    8786457

  Z                7588      16434

  intensity        1542      65535

  return_number       1          1

  number_of_returns   1          1

  edge_of_flight_line 0          0

  scan_direction_flag 1          1

  classification      0          0

  scan_angle_rank     0          0

  user_data           0          0

  point_source_ID     1          1

  Color R 0 65535

        G 0 65535

        B 0 65535

number of first returns:        50454236

number of intermediate returns: 0

number of last returns:         50454236

number of single returns:       50454236

overview over number of returns of given pulse: 50454236 0 0 0 0 0 0

histogram of classification of points:

        50454236  never classified (0)