Convert 3dep lidar unit from feet to meters

JinYuan SHAO

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Dec 17, 2021, 1:38:05 AM12/17/21

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Hi there, I'm trying to use las2las to convert Indiana States 3DEP lidar point cloud.

I'm not sure my command is right or not.

las2las -epsg 2966 -target_epsg 32616 -feet -target_meter -elevation_feet -target_elevation_meter -i xxx.las -o xxx.las

The new file can be generated, but there is always a warning information:

SERIOUS WARNING: horizontal datum of source and target incompatible.

I'm not very clear about georeference system cause I'm new in this field.

Could you please tell me what is the right command that convert feet to meters?

Hope the attachment is helpful.

Thank you

3DEP1_1.las

George S. Mercier

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Dec 18, 2021, 1:00:06 PM12/18/21

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Seems you are trying to go from NAD83 Datum / State Plane projection to WGS84 Datum / UTM 16N:

if you use: las2las -i 3DEP1_1.las -o 3DEP1_1-utm-meter.las -sp83 IN_W -feet -elevation_feet -wgs84 -target_utm auto

the target_utm auto puts you in UTM 14N as show by lasinfo report below:

lasinfo -i 3DEP1_1-utm-meter.las
lasinfo (210720) report for '3DEP1_1-utm-meter.las'
reporting all LAS header entries:
file signature: 'LASF'
file source ID: 0
global_encoding: 1
project ID GUID data 1-4: 40541EE0-9961-4C2C-D58F-AF4F440E30D7
version major.minor: 1.2
system identifier: 'LAStools (c) by rapidlasso GmbH'
generating software: 'las2las (version 210720)'
file creation day/year: 38/2012
header size: 227
offset to point data: 1237
number var. length records: 3
point data format: 1
point data record length: 28
number of point records: 4792
number of points by return: 2824 1645 313 10 0
scale factor x y z: 0.01 0.01 0.01
offset x y z: 700000 4400000 0
min x y z: 711187.63 4479109.84 237.20
max x y z: 711266.55 4479188.81 269.75
variable length header record 1 of 3:
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 32614 - ProjectedCSTypeGeoKey: WGS 84 / UTM 14N
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 2 of 3:
reserved 43707
user ID 'NIIRS10'
record ID 1
length after header 26
description 'NIIRS10 Tile Index'
variable length header record 3 of 3:
reserved 43707
user ID 'NIIRS10'
record ID 4
length after header 10
description 'NIIRS10 Timestamp'
the header is followed by 772 user-defined bytes
reporting minimum and maximum for all LAS point record entries ...
X 1118763 1126655
Y 7910984 7918881
Z 23720 26975
intensity 1 240
return_number 1 4
number_of_returns 1 4
edge_of_flight_line 0 0
scan_direction_flag 0 1
classification 1 7
scan_angle_rank 5 7
user_data 149 156
point_source_ID 1096 1096
gps_time -15497519.168685 -15497518.054589
number of first returns: 2824
number of intermediate returns: 326
number of last returns: 2820
number of single returns: 1178
overview over number of returns of given pulse: 1178 2653 924 37 0 0 0
histogram of classification of points:
2108 unclassified (1)
2677 ground (2)
7 noise (7)

So maybe use this to force your target utm zone:

las2las -i 3DEP1_1.las -o 3DEP1_1-utm16-meter.las -sp83 IN_W -feet -elevation_feet -wgs84 -target_utm 16N

LASINFO: lasinfo -i 3DEP1_1-utm16-meter.las
lasinfo (210720) report for '3DEP1_1-utm16-meter.las'
reporting all LAS header entries:
file signature: 'LASF'
file source ID: 0
global_encoding: 1
project ID GUID data 1-4: 40541EE0-9961-4C2C-D58F-AF4F440E30D7
version major.minor: 1.2
system identifier: 'LAStools (c) by rapidlasso GmbH'
generating software: 'las2las (version 210720)'
file creation day/year: 38/2012
header size: 227
offset to point data: 1237
number var. length records: 3
point data format: 1
point data record length: 28
number of point records: 4792
number of points by return: 2824 1645 313 10 0
scale factor x y z: 0.01 0.01 0.02
offset x y z: -300000 4500000 0
min x y z: -307175.27 4519793.85 237.20000000000002
max x y z: -307095.59 4519873.29 269.74000000000001
variable length header record 1 of 3:
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 32616 - ProjectedCSTypeGeoKey: WGS 84 / UTM 16N
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 2 of 3:
reserved 43707
user ID 'NIIRS10'
record ID 1
length after header 26
description 'NIIRS10 Tile Index'
variable length header record 3 of 3:
reserved 43707
user ID 'NIIRS10'
record ID 4
length after header 10
description 'NIIRS10 Timestamp'
the header is followed by 772 user-defined bytes
reporting minimum and maximum for all LAS point record entries ...
X -717527 -709559
Y 1979385 1987329
Z 11860 13487
intensity 1 240
return_number 1 4
number_of_returns 1 4
edge_of_flight_line 0 0
scan_direction_flag 0 1
classification 1 7
scan_angle_rank 5 7
user_data 149 156
point_source_ID 1096 1096
gps_time -15497519.168685 -15497518.054589
number of first returns: 2824
number of intermediate returns: 326
number of last returns: 2820
number of single returns: 1178
overview over number of returns of given pulse: 1178 2653 924 37 0 0 0
histogram of classification of points:
2108 unclassified (1)
2677 ground (2)
7 noise (7)

Evon Silvia

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Dec 18, 2021, 1:00:17 PM12/18/21

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Hello and welcome to the list.

Your commands are attempting to transform from EPSG 2966 (https://epsg.org/crs_2966/NAD83-Indiana-West-ftUS.html) to EPSG 32616 (https://epsg.org/crs_32616/WGS-84-UTM-zone-16N.html).

las2las is correctly warning you that the underlying datums for the CRS selections – in this case, NAD83 and WGS84 – are different and it cannot transform from one to the other.

It probably won’t change any of the resultant XY positions, but the more correct target_epsg in your case is probably EPSG 26916 (https://epsg.org/crs_26916/NAD83-UTM-zone-16N.html).

If you actually want to switch from NAD83 to WGS84, however, that’s an entirely different thing… I doubt that's what you what.

--

Evon Silvia | Solutions Architect | ASPRS LAS Working Group Chair

NV5 Geospatial, formerly Quantum Spatial

Evon Silvia

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Dec 21, 2021, 1:58:56 AM12/21/21

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It's worth noting that the LAS file's header indicate that your file is in Indiana State Plane East zone, not the West zone. That's probably why "-utm auto" says it's in UTM zone 14 instead of UTM zone 16.

If that's true, you'll want to use EPSG code 2965 (https://epsg.org/crs_2965/NAD83-Indiana-East-ftUS.html) as your source CRS.

Evon

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