Hello from @LAStools,
gilles_3Dreshaper wrote: ↑Fri Apr 06, 2018 2:42 pm
Here is a small zip file containing a LAS and a LAZ file exported from 3DReshaper.
LAS+LAZ.zip
Let me know what your findings are about the lasinfo report.
To export a LAS (or LAZ) file in 3DReshaper, just select the point cloud, go to File / Export / Export Selected Cloud(s) and choose the right extension!
I had a look at the
lasinfo report and it looks good except the scale factors and the offset values. This is not the way the LAS / LAZ format was intended to be used. The value in the scale factors specified with what resolution the coordinates are stored and it should match the expected accuracy of the point coordinates. For airborne scans we tend to use scale factors 0.01 0.01 0.01 (aka cm resolution). For mobile scans we tend to use scale factors 0.001 0.001 0.001 (aka mm resolution). For terrestrial scans we tend to use scale factors 0.00025 0.00025 0.00025 (aka quarter-mm resolution).
Your LAS/LAZ files store each point with approximately 9 decimal digits (the digits to the right of the decimal point) because it uses scale factors of 0.000000000150398 0.000000000169045 0.00000000020536. That corresponds to
nanometer resolution, which is clearly excessive unless you are scanning with an electron-microscope ... (-:
Also your offsets are really not nice to look at. We usually pick some "rounded" coordinate that is near the point coordinates. The offset is not really needed for local coordinate systems where numbers are close to zero. They are really needed only for projected coordinates (e.g. UTM), geocentric (ECEF), or geometric (long/lat) coordinates where the bounding box enclosing the points is far from zero.
Below I show how to rescale / reoffset the LAZ file you have provided using free and open source
las2las of
LAStools. Also note the reduction in file size of down to about a third. The nanometer coordinates are not actual information but just whatever "white noise" happened to be in the registers after the floating-point calculations. And "white noise" is more or less incompressible.
Code: Select all
E:\LAStools\bin>las2las -i "Cloud&Inspection.laz" ^
-rescale 0.00025 0.00025 0.00025 ^
-auto_reoffset ^
-odix _qmm -olaz
BEFORE (size 48,862 bytes)
Code: Select all
E:\LAStools\bin>lasinfo -i "Cloud&Inspection.laz"
lasinfo (180620) report for 'Cloud&Inspection.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: 'OTHER'
generating software: 'LASzip DLL 3.1 r0 (170823)'
file creation day/year: 95/118
header size: 227
offset to point data: 227
number var. length records: 0
point data format: 2
point data record length: 26
number of point records: 4348
number of points by return: 0 0 0 0 0
scale factor x y z: 0.000000000150398 0.000000000169045 0.00000000020536
offset x y z: -5.061584502268218 4.296448214330293 0.172332938826083
min x y z: -5.362380981254958 3.958358986653901 -0.238388005578519
max x y z: -4.760788023281478 4.634537442006685 0.583053883230685
LASzip compression (version 3.1r0 c2 50000): POINT10 2 RGB12 2
reporting minimum and maximum for all LAS point record entries ...
X -2000000000 2000000000
Y -2000000000 2000000000
Z -2000000000 2000000000
intensity 0 65535
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
Color R 29555 30840
G 22873 51914
B 5397 39064
number of first returns: 4348
number of intermediate returns: 0
number of last returns: 4348
number of single returns: 4348
WARNING: for return 1 real number of points by return is 4348 but header entry was not set.
overview over number of returns of given pulse: 4348 0 0 0 0 0 0
histogram of classification of points:
4348 never classified (0)
AFTER (size 15,951)
Code: Select all
E:\LAStools\bin>lasinfo -i "Cloud&Inspection_qmm.laz"
lasinfo (180620) report for 'Cloud&Inspection_qmm.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 180620)'
file creation day/year: 95/118
header size: 227
offset to point data: 227
number var. length records: 0
point data format: 2
point data record length: 26
number of point records: 4348
number of points by return: 4348 0 0 0 0
scale factor x y z: 0.00025 0.00025 0.00025
offset x y z: 0 0 0
min x y z: -5.36250 3.95825 -0.23850
max x y z: -4.76075 4.63450 0.58300
LASzip compression (version 3.2r4 c2 50000): POINT10 2 RGB12 2
reporting minimum and maximum for all LAS point record entries ...
X -21450 -19043
Y 15833 18538
Z -954 2332
intensity 0 65535
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
Color R 29555 30840
G 22873 51914
B 5397 39064
number of first returns: 4348
number of intermediate returns: 0
number of last returns: 4348
number of single returns: 4348
overview over number of returns of given pulse: 4348 0 0 0 0 0 0
histogram of classification of points:
4348 never classified (0)