Cloudcompare issue when exporting to las/laz

[a.cottin]

Martin,

For your information.

I downloaded the last build for OsX (2.5.5.2 from 2014-07-21) of Cloudcompare this morning, and did a quick merge of 5 las files.

I ended up with a file having ugly scale and offset values.

Original las file header of one of the file used:

  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:          'YellowScan'

  generating software:        'txt2las (version 120522)'

  file creation day/year:     333/2011

  header size:                227

  offset to point data:       227

  number var. length records: 0

  point data format:          0

  point data record length:   20

  number of point records:    885635

  number of points by return: 661786 195328 28521 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               200000 500000 0

  min x y z:                  286314.70 582804.85 6.76

  max x y z:                  286560.28 583813.26 66.48

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

  X             8631470    8656028

  Y             8280485    8381326

  Z                 676       6648

  intensity          12        496

  return_number       1          3

  number_of_returns   1          3

  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

overview over number of returns of given pulse: 415136 357681 112818 0 0 0 0

histogram of classification of points:

          885635 never classified (0)

Header of the merge saved file:

  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:          'libLAS'

  generating software:        'libLAS 1.7.0'

  file creation day/year:     250/2014

  header size:                227

  offset to point data:       227

  number var. length records: 0

  point data format:          3

  point data record length:   34

  number of point records:    5528589

  number of points by return: 0 0 0 0 0

  scale factor x y z:         0.000000394349976 0.000001145290039 0.000000071439995

  offset x y z:               286297.20001220703125 582804.849999904632568 3.619999885559082

  min x y z:                  286297.20001220703125 582804.849999904632568 3.619999885559082

  max x y z:                  286691.550003051757812 583950.1400146484375 75.05999755859375

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

  X                   0 1000000039

  Y                   0  999999979

  Z                   0 1000000040

  intensity          12        544

  return_number       1          3

  number_of_returns   1          3

  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

  gps_time 0.000000 0.000000

  Color R 0 0

        G 0 0

        B 0 0

WARNING: 1 points outside of header bounding box

number of points by return was not set in header: 4152318 1205568 170703 0 0

overview over number of returns of given pulse: 2594988 2237645 695956 0 0 0 0

histogram of classification of points:

         5528589 never classified (0)

real max x larger than header max x by 0.000000

I've been fooled one time... but not twice ;)

Antoine

[D Lague]

Hi Antoine,

maybe you could highlight the bug in the Cloudcompare forum and contribute to the development of this great piece of software.

Daniel Girardeau-Montaut develops it entirely on its free time, for free, and is generally quite responsive when it comes to correct bugs.

He has added the possibility to open and save las files following user suggestions, even though I know that he does not need it for his own usage.

La critique est facile, l'art est difficile ;-)

Dimitri

[Daniel Girardeau-Montaut]

See the more recent discussion about this 'issue' here: https://groups.google.com/forum/#!topic/lastools/fuKbmMbLHSo.

This is not a bug, and it doesn't change the data accuracy.

Not sure to understand this "fooled once, not twice" thing. Next time don't hesitate to post a message on CC's forum or send us an email. We are always keen to fix 'bugs' and improve the software (or even simply to be challenged on such questions - it's a good way to increase the confidence in a tool).