reprojecting co-ordinates in las2las

Alice Thorne

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Sep 4, 2016, 5:05:54 AM9/4/16

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Hello,

Is it possible to reproject a LAS file currently in ESPG 3857 to ESPG 4326 using LAStools? ( I cannot find 4326 in the ESPG export options in Las2Las)

Best, Alice

Martin Isenburg

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Sep 6, 2016, 7:17:54 AM9/6/16

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Hello Alice,

the problem is not the target EPSG code 4326 that simply refers to longlat coordinates in WGS84 and that can be reprojected to if you have any supported projected coordinates that are also in WGS84 via both these commands below.

E:\LAStools\bin>las2las -i ..\data\fusa.laz -target_epsg 4326 -odix _4326 -olaz

E:\LAStools\bin>las2las -i ..\data\fusa.laz -target_longlat -odix _ll -olaz

using target projection 'longitude/latitude'

E:\LAStools\bin>lasdiff -i ..\data\fusa_4326.laz -i ..\data\fusa_ll.laz

checking '..\data\fusa_4326.laz' against '..\data\fusa_ll.laz'

headers are identical.

raw points are identical.

files are identical. both have 277573 points. took 0.634 secs.

But your source projection is EPSG code 3857 which uses the (rare?) Mercator_1SP projection (also see http://epsg.io/3857) that is not implemented at the moment.

E:\LAStools\bin>las2las -i ..\data\fusa.laz -epsg 3857 -target_epsg 4326 -odix _4326 -olaz

transform 1024 of EPSG code 3857 not implemented.

ERROR: unknown EPSG code in '-epsg 3857'.

This is the first time I hear of LiDAR being in this projection ... is anyone else using this projection for LiDAR?

Regards,

Martin @rapidlasso

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

E:\LAStools\bin>lasinfo -i ..\data\fusa_ll.laz

lasinfo (160804) report for ..\data\fusa_ll.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: 'las2las (version 160822)'

file creation day/year: 40/2010

header size: 227

offset to point data: 313

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: 0.0000001 0.0000001 0.01

offset x y z: 138 -35 0

min x y z: 138.5641483 -35.0180436 42.21

max x y z: 138.5669489 -35.0157388 64.35

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 2.4r2 c2 50000): POINT10 2 GPSTIME11 2

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

X 5641483 5669489

Y -180436 -157388

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)

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

E:\LAStools\bin>lasinfo -i ..\data\fusa_4326.laz

lasinfo (160804) report for ..\data\fusa_4326.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: 'las2las (version 160822)'

file creation day/year: 40/2010

header size: 227

offset to point data: 313

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: 0.0000001 0.0000001 0.01

offset x y z: 138 -35 0

min x y z: 138.5641483 -35.0180436 42.21

max x y z: 138.5669489 -35.0157388 64.35

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 2.4r2 c2 50000): POINT10 2 GPSTIME11 2

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

X 5641483 5669489

Y -180436 -157388

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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alice thorne

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Sep 7, 2016, 2:18:42 AM9/7/16

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Hi Martin,

The data set is a photogrametric point cloud rather than ASL. I am not sure why the EPSG code 3857 was used to generate it, and thanks very much for your advice,

Best, Alice

From: martin....@gmail.com
Date: Tue, 6 Sep 2016 13:15:51 +0200
Subject: Re: [LAStools] reprojecting co-ordinates in las2las
To: last...@googlegroups.com

Albert Godfrind

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Sep 7, 2016, 3:31:08 AM9/7/16

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3857 is a very special projection. It is also known as the “google projection”, introduced by Google for Google Maps. It is a Mercator projection - but based on a fully spherical representation of the earth. Nowadays it is used by pretty much all online mapping services (Google, Bing, Mapquest, Here, TomTom, etc). All GIS tools and projection libraries are able to transform between 3857 and any other coordinate systems. See

But it is not designed for storing data … I am also very surprised that LIDAR data (or any data) would be produced in that coordinate system. Maybe the source is really not in 3857 but in 3395. That is also a global mercator projection, but based on the WGS84 ellipsoid ...

Albert

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Albert Godfrind

albert....@oracle.com

+33 6 09 97 27 23

Terje Mathisen

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Sep 7, 2016, 4:37:13 AM9/7/16

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Albert Godfrind wrote:
> 3857 is a very special projection. It is also known as the “google
> projection”, introduced by Google for Google Maps. It is a Mercator

> projection - but based on a fully *spherical* representation of the

> earth. Nowadays it is used by pretty much all online mapping services
> (Google, Bing, Mapquest, Here, TomTom, etc). All GIS tools and
> projection libraries are able to transform between 3857 and any other
> coordinate systems. See

Very interesting.

Many, many years ago (1993) Microsoft produced a CD world atlas. I was
challenged by a friend who worked for MS to work out the projections
needed, it turned out that their model of the world was based on a cube
which touched a hypotethical spherical world in the center of each of
the 6 faces, and which had a long diagonal coinciding with the North
Pole - South Pole axis. I don't remember exactly but I believe they also
made sure that one of the top three faces was centered over the US which
meant that the next (going east) covered Europe and the third was over
Asia, i.e. placing the face boundaries mostly over oceans.

The projection is of course similar to the setup used by many spherical
photo viewers.

Terje

>
> But it is not designed for storing data … I am also very surprised
> that LIDAR data (or any data) would be produced in that coordinate
> system. Maybe the source is really not in 3857 but in 3395. That is
> also a global mercator projection, but based on the WGS84 ellipsoid ...
>
> Albert
>
>> On 6-Sep-2016, at 13:15, Martin Isenburg <martin....@gmail.com

>> http://lastools.org <http://lastools.org/>
>> http://rapidlasso.com <http://rapidlasso.com/>

>> Be social with LAStools at
>> http://facebook.com/LAStools
>> http://twitter.com/LAStools
>> http://linkedin.com/groups/LAStools-4408378
>> <http://linkedin.com/groups/LAStools-4408378>
>> Manage your settings at
>> http://groups.google.com/group/lastools/subscribe
>> <http://groups.google.com/group/lastools/subscribe>
>>
>>
>>
>> --
>> Download LAStools at

>> http://lastools.org <http://lastools.org/>
>> http://rapidlasso.com <http://rapidlasso.com/>

>> Be social with LAStools at
>> http://facebook.com/LAStools
>> http://twitter.com/LAStools
>> http://linkedin.com/groups/LAStools-4408378
>> Manage your settings at
>> http://groups.google.com/group/lastools/subscribe
>
> --
> Albert Godfrind

> albert....@oracle.com <mailto:albert....@oracle.com>

> +33 6 09 97 27 23
>
>
>
>

> --
> Download LAStools at
> http://lastools.org
> http://rapidlasso.com
> Be social with LAStools at
> http://facebook.com/LAStools
> http://twitter.com/LAStools
> http://linkedin.com/groups/LAStools-4408378
> Manage your settings at
> http://groups.google.com/group/lastools/subscribe

--

- <Terje.M...@tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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