How to convert Netherlands AHN3 LIDAR data (LAZ FORMAT) to WGS84 longitude/latitude??

dong chen

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Jul 24, 2018, 12:24:02 AM7/24/18

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Dear Martin,

I have AHN3 point clouds like below:

177030.670 503789.560 0.230 255 255 255 1.7

177030.600 503789.670 -2.110 255 255 255 15.8

177030.520 503788.960 0.260 255 255 255 12.7

177030.540 503788.960 -1.310 255 255 255 16.2

177028.310 503791.110 0.250 255 255 255 7.1

177028.490 503790.880 0.210 255 255 255 3.3

177030.420 503788.430 0.250 255 255 255 9.8

177030.470 503788.380 -1.050 255 255 255 10.9

177027.840 503791.180 0.270 255 255 255 9.6

177028.010 503790.960 0.180 255 255 255 1.7

177030.330 503788.010 0.220 255 255 255 6.9

177030.520 503787.770 0.260 255 255 255 2.9

177030.410 503787.930 -0.740 255 255 255 10.4

177027.380 503791.190 0.240 255 255 255 13.1

177027.590 503790.920 0.220 255 255 255 3.4

Could you tell me how to convert these points to longitude/latitude, using lastool? Many thanks.

Dong Chen

Martin Isenburg

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Jul 24, 2018, 1:33:48 AM7/24/18

to LAStools - efficient command line tools for LIDAR processing

Hello Dong,

Do you know what projection and what horizontal datum those points are currently in? I would need to know the current coordinate reference system (CRS) of the points to tell you how to convert them to geographic coordinates in long/lat format in WGS84.

Regards,

Martin

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dong chen

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Jul 24, 2018, 10:28:48 PM7/24/18

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Dear Martin,

the EPSG code is 7415 (xy Amersfoort / RDnew and z NAP height).

Hope these info is enough for translation.

在 2018年7月23日星期一 UTC-6下午11:33:48，Martin Isenburg写道：

Martin Isenburg

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Aug 2, 2018, 9:44:06 AM8/2/18

to LAStools - efficient command line tools for LIDAR processing

Hello,

try this workflow but be careful with each step:

E:\LAStools\bin>txt2las -i ahn3.txt -epsg 28992 -o ahn3.laz

done with 'ahn3.laz'. total time 0.015 sec.

E:\LAStools\bin>lasinfo -i ahn3.laz

lasinfo (180731) report for 'ahn3.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: 1.2

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

generating software: 'txt2las (version 180731)'

file creation day/year: 214/2018

header size: 227

offset to point data: 321

number var. length records: 1

point data format: 0

point data record length: 20

number of point records: 15

number of points by return: 15 0 0 0 0

scale factor x y z: 0.01 0.01 0.01

offset x y z: 100000 500000 0

min x y z: 177027.38 503787.77 -2.11

max x y z: 177030.67 503791.19 0.27

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 28992 - ProjectedCSTypeGeoKey: Amersfoort / RD New

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 3.2r4 c2 50000): POINT10 2

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

X 7702738 7703067

Y 378777 379119

Z -211 27

intensity 0 0

return_number 1 1

number_of_returns 1 1

edge_of_flight_line 0 0

scan_direction_flag 0 0

classification 0 0

scan_angle_rank 0 0

user_data 0 0

point_source_ID 0 0

number of first returns: 15

number of intermediate returns: 0

number of last returns: 15

number of single returns: 15

overview over number of returns of given pulse: 15 0 0 0 0 0 0

histogram of classification of points:

15 never classified (0)

E:\LAStools\bin>las2las -i ahn3.laz -target_ecef -odix _ecef -olaz

using target projection 'earth-centered earth-fixed'

E:\LAStools\bin>lasinfo -i ahn3_ecef.laz

lasinfo (180731) report for 'ahn3_ecef.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: 1.2

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

generating software: 'las2las (version 180731)'

file creation day/year: 214/2018

header size: 227

offset to point data: 305

number var. length records: 1

point data format: 0

point data record length: 20

number of point records: 15

number of points by return: 15 0 0 0 0

scale factor x y z: 0.01 0.01 0.01

offset x y z: 3800000 300000 5000000

min x y z: 3869209.00 387032.66 5037862.47

max x y z: 3869211.95 387036.06 5037865.29

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 4004 - GeographicTypeGeoKey: GCSE_Bessel1841

LASzip compression (version 3.2r4 c2 50000): POINT10 2

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

X 6920900 6921195

Y 8703266 8703606

Z 3786247 3786529

intensity 0 0

return_number 1 1

number_of_returns 1 1

edge_of_flight_line 0 0

scan_direction_flag 0 0

classification 0 0

scan_angle_rank 0 0

user_data 0 0

point_source_ID 0 0

number of first returns: 15

number of intermediate returns: 0

number of last returns: 15

number of single returns: 15

overview over number of returns of given pulse: 15 0 0 0 0 0 0

histogram of classification of points:

15 never classified (0)

E:\LAStools\bin>las2las -i ahn3_ecef.laz -ecef -wgs84 -transform_helmert 565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725 -odix _towgs84 -olaz

using projection 'earth-centered earth-fixed'

using datum 'WGS 84' with ellipsoid 'WGS-84'

E:\LAStools\bin>lasinfo -i ahn3_ecef_towgs84.laz

lasinfo (180731) report for 'ahn3_ecef_towgs84.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: 1.2

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

generating software: 'las2las (version 180731)'

file creation day/year: 214/2018

header size: 227

offset to point data: 305

number var. length records: 1

point data format: 0

point data record length: 20

number of point records: 15

number of points by return: 15 0 0 0 0

scale factor x y z: 0.01 0.01 0.01

offset x y z: 3800000 300000 5000000

min x y z: 3869802.10 387059.10 5038341.34

max x y z: 3869805.05 387062.50 5038344.16

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 3.2r4 c2 50000): POINT10 2

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

X 6980210 6980505

Y 8705910 8706250

Z 3834134 3834416

intensity 0 0

return_number 1 1

number_of_returns 1 1

edge_of_flight_line 0 0

scan_direction_flag 0 0

classification 0 0

scan_angle_rank 0 0

user_data 0 0

point_source_ID 0 0

number of first returns: 15

number of intermediate returns: 0

number of last returns: 15

number of single returns: 15

overview over number of returns of given pulse: 15 0 0 0 0 0 0

histogram of classification of points:

15 never classified (0)

E:\LAStools\bin>las2las -i ahn3_ecef_towgs84.laz -target_longlat -o ahn3_longlat_wgs84.laz

using target projection 'longitude/latitude'

E:\LAStools\bin>lasinfo ahn3_longlat_wgs84.laz

lasinfo (180731) report for 'ahn3_longlat_wgs84.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: 1.2

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

generating software: 'las2las (version 180731)'

file creation day/year: 214/2018

header size: 227

offset to point data: 313

number var. length records: 1

point data format: 0

point data record length: 20

number of point records: 15

number of points by return: 15 0 0 0 0

scale factor x y z: 0.0000001 0.0000001 0.01

offset x y z: 5 52 0

min x y z: 5.7117488 52.5213127 40.58

max x y z: 5.7117972 52.5213436 42.97

variable length header record 1 of 1:

reserved 0

user ID 'LASF_Projection'

record ID 34735

length after header 32

description 'by LAStools of rapidlasso GmbH'

GeoKeyDirectoryTag version 1.1.0 number of keys 3

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

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

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

LASzip compression (version 3.2r4 c2 50000): POINT10 2

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

X 7117488 7117972

Y 5213127 5213436

Z 4058 4297

intensity 0 0

return_number 1 1

number_of_returns 1 1

edge_of_flight_line 0 0

scan_direction_flag 0 0

classification 0 0

scan_angle_rank 0 0

user_data 0 0

point_source_ID 0 0

number of first returns: 15

number of intermediate returns: 0

number of last returns: 15

number of single returns: 15

overview over number of returns of given pulse: 15 0 0 0 0 0 0

histogram of classification of points:

15 never classified (0)

ahn3.txt

dong chen

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Aug 6, 2018, 8:35:15 AM8/6/18

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Many thanks. Martin it works.

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