Problem with lasoverage

[João Fonte]

Hi,

I'm using a batch file to process with LAStools (latest available version, unlicensed) a large volume of airborne LiDAR data, using a combination of lastile, lasoverage, lasground and blast2dem commands. However, every time it gets to the lasoverage processing, LAStools crashes, but if I only use the other commands I have no problem with the processing. Anyone had a similar problem with lasoverage? Any ideas?

Many thanks!

João Fonte

[Martin Isenburg]

Hello Joao,

could you upgrade to the latest version of LAStools (180620 from yesterday) and see if the problem is gone:

http://rapidlasso.com/LAStools

other CHANGES:

20 June 2018 -- LASlib, all LAStools: fix for '-set_classification 0' transform for new LAS 1.4 point types 6-10

20 June 2018 -- lascontrol: generate report even if input point data does not cover any of the control points

17 June 2018 -- LASlib, all LAStools: fix in flag copy from old LAS 1.3 (0-5) to new LAS 1.4 point types (6-10)

16 June 2018 -- txt2las: new option '-set_global_encoding 1' because this bit is simply so often set wrong

12 June 2018 -- las2las: new option '-set_global_encoding_gps_bit 1' because this bit is simply so often set wrong

11 June 2018 -- lasview: new option '-points_all' loads all points from input (especially useful for manual editing)

10 June 2018 -- LASlib, all LAStools: fix for additional attributes in "extra bytes" combined with '-buffered 15'

Regards,

Martin @rapidlasso

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[David Friedrich]

Hi João,

well you will have to provide more information. For exaamle the exact lascoverage command you are using and the error message thrown.

Cheers,

David

--

[João Fonte]

Hi Martin,

I have updated LAStools to the last version and now lasoverage seems to be working fine, many thanks!

David, basically I was using -step and -remove_overage with lasoverage.

Best wishes,

João

[João Fonte]

Hi Martin,

Sorry again, but I'm having some problems with the DTM interpolation,
in particular continuous strips that seem to be due to the lack to
data on those areas (please see attached image), but is not really a
problem of lack of points because the point clouds had data on those
areas. Any ideas?

This is the command I'm using:

mkdir 1-tiles
lastile -i *.las -tile_size 500 -buffer 20 -odir 1-tiles -o tile.laz -cores 8

cd 1-tiles

mkdir 2-overage
lasoverage -i *.laz -odir 2-overage -o overage.laz -step 1.2
-remove_overage -cores 8

cd 2-overage

mkdir 3-dem
blast2dem -i *.laz -translate_raw_xy_at_random 2 2 -odir 3-dem -o
dem.tif -use_tile_bb -keep_class 2 -step 1 -kill 500 -cores 8

Many thanks!

Best wishes,

Joao

[Martin Isenburg]

Hello João,

It seems that your data is already ground classified. If you first perform the ground classification and then drop the overage points from the flightline overlap then there is a possibility that you drop entire strips of ground points.

http://rapidlasso.com/lasoverage

http://lastools.org/download/lasoverage_README.txt

It would be better to remove the overage points before doing the ground classification. I assume that you will find the missing ground points if you only visualize the class 2 (ground) points that you are triangulating with blast2dem.

Regards,

Martin @rapidlasso

[João Fonte]

Many thanks Martin! Yes, my data is already ground classified. So, if
I want to keep that classification, should it be better to remove the
overage points in relation only to the ground points or for the
overage calculation I really need to do another ground classification?
Sorry, but it's just to sure sure on this.

Best wishes,

João

[Martin Isenburg]

Hello,

for data that is already ground classified you do not have to remove the overage. Just use all points that pass the '-keep_class 2' filter. This will also save you from having this - then unnecessary - run of lasoverage in your pipeline. The decision whether or not to remove the overage for ground classified data should only be of relevance for the (rare) case that each flightline was ground-classified individually (as it is possible with lasground's option '-by_flightline').

http://rapidlasso.com/lasground
http://lastools.org/download/lasground_README.txt

Usually you will use all remaining ground points as the removal / classification of overage points tends to happen before the ground classification step.

Regards,

Martin @rapidlasso

[Tobias K Kohoutek]

Dear Martin,

following up on the original problem, I'm facing also a crash of lasoverage (version 181520 and 180706) of several flightline files with the following Error:

.

.

.

ERROR: cannot alloc LASrasterTile

ERROR: cannot alloc tile

ERROR: cannot get tile (844865/14464700)

ERROR: cannot alloc LASrasterTile

ERROR: cannot alloc tile

ERROR: cannot get tile (844800/14464698)

abnormal program termination

Any ideas?

lasinfo report of one of the input lines is the following:

EPSG code 0 not found in 'pcs.csv' file

set_ProjectedCSTypeGeoKey: look-up for 0 not implemented

lasinfo -i "d:\2752_1803_CE_Taltal\temp\reprojection\cld_180627_01_145643_002CL.laz" -cd

lasinfo (180706) report for 'd:\2752_1803_CE_Taltal\temp\reprojection\cld_180627_01_145643_002CL.laz'

reporting all LAS header entries:

  file signature:             'LASF'

  file source ID:             2

  global_encoding:            1

  project ID GUID data 1-4:   01139D6D-0000-0000-6F42-746F0000724E

  version major.minor:        1.2

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

  generating software:        'las2las (version 180520)'

  file creation day/year:     199/2018

  header size:                227

  offset to point data:       323

  number var. length records: 1

  point data format:          1

  point data record length:   28

  number of point records:    10411968

  number of points by return: 10411942 26 0 0 0

  scale factor x y z:         0.01 0.01 0.01

  offset x y z:               500000 7224000 0

  min x y z:                  408235.51 7221213.01 1858.64

  max x y z:                  409312.68 7224019.11 1942.37

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 32719 - ProjectedCSTypeGeoKey: WGS 84 / UTM 19S

      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

the header is followed by 2 user-defined bytes

LASzip compression (version 3.2r3 c2 50000): POINT10 2 GPSTIME11 2

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

  X            -9176449   -9068732

  Y             -278699       1911

  Z              185864     194237

  intensity          46      14703

  return_number       1          2

  number_of_returns   1          2

  edge_of_flight_line 0          1

  scan_direction_flag 1          1

  classification      1          1

  scan_angle_rank   -19         19

  user_data           0          0

  point_source_ID     2          2

  gps_time 214146607.080926 214146684.751486

number of first returns:        10411942

number of intermediate returns: 0

number of last returns:         10411942

number of single returns:       10411916

covered area in square meters/kilometers: 1499640/1.50

point density: all returns 6.94 last only 6.94 (per square meter)

      spacing: all returns 0.38 last only 0.38 (in meters)

overview over number of returns of given pulse: 10411916 52 0 0 0 0 0

histogram of classification of points:

        10411968  unclassified (1)

Cheers,
Tobias

[Martin Isenburg]

Hello,

the same problem here. Out of memory. In the future the ERROR message will be more clear. But you now have the 64 bit compile 'lasoverage64' that can be started simply by adding '-cpu64' to your existing command line. This is as of version 180911.

http://rapidlasso.com/LAStools

Regards,

Martin