lasgrid

[Susana Gonzalez]

Hi all,

Why lasgrid doesn’t merge .tif to a new TIF raster?

 

This line doesn’t work

C:\LAStools\bin\lasgrid.exe -v -i J:\Outputs_Raster\*_dns.tif -merged -step 4 -highest -o J:\Analysis\dns.tif

 

 

Later I have tried .bil and it’s working fine

C:\LAStools\bin\lasgrid.exe -v -i J:\Outputs_Raster\*_dns.bil -merged -step 4 -highest -o J:\Analysis\dns.tif

 

My LAStools version is 29 April 2016

Cheers

 

Susana Gonzalez

Forest Engineer, LiDAR Science

 

Interpine Group Ltd

NZ Office: 07 350 3209 extn 722

Australia: 02 8011 3645

Address: 99 Sala Street, PO Box 1209, Rotorua 3010, New Zealand

Website: www.interpine.co.nz

 

[Martin Isenburg]

Hello Susana,

lasgrid - as the name suggests - is for LAS / LAZ files. For convenience I have added support for a few other formats to the LASlib library (in particular the lasreader) so that points can be read from NASA's *.qi format, Leica's *.pts and *.ptx formats, ESRI's *.shp format, Terrasolid's *.bin format, and from most simple ASCII files. Furthermore I have added support to allow reading a few simple raster formats as points via "on-the-fly" conversion because that can be convenient sometimes. This is only available for simple raster formats, namely ASCII grids in *.asc format and binary grids in *.dtm and *.bil format. Adding support for more complex raster format would introduce compile dependencies into our core LASlib library ... something we have been trying to avoid.

The fact that lasgrid can "merge rasters" is more of an accidental feature than a planned one. There are many excellent raster tools out there that are meant for merging rasters. I would recommend using GDAL for this:

http://www.gdal.org/gdal_merge.html

One alternate way - assuming your input rasters are temporary - would be for me to add LAS/LAZ as an *output* format for storing (temporary) rasters as this turns out to be a very efficient way of doing so.

http://groups.google.com/d/topic/lastools/vl_FaA2WbCM/discussion

Especially for multi-core processing the O limitation of your file system I/O will significantly slow you down if all your temporary rasters are stored uncompressed to disk (e.g. BIL, ASC, or DTM). Using LAZ instead could prove to give you a substantial saving in end-to-end wall clock time if you are indeed heavily I/O bound.

Regards,

Martin @rapidlasso

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[Floris Groesz]

adding .laz as an output format for temporary grids would be nice.
At the moment I use .bil as temporary format for grid tiles.
I know that GDAL can merge/mosaic well, but most of the times it is convenient to run a complete process in LAStools.

Floris

[Martin Isenburg]

Hello,

In the newest release of LAStools  (160730 of today) the tools 'lasgrid', 'las2dem', 'lascanopy' and 'lasoverlap' will support the generation of output rasters in LAZ format.

http://rapidlasso.com/lasgrid
http://lastools.org/download/lasgrid_README.txt
http://rapidlasso.com/las2dem
http://lastools.org/download/las2dem_README.txt
http://rapidlasso.com/lascanopy
http://lastools.org/download/lascanopy_README.txt
http://rapidlasso.com/lasoverlap
http://lastools.org/download/lasoverlap_README.txt

This new addition allows very compressed storage of elevation rasters. Especially for the LAStools pipeline for generating pit-free CHMs this can be beneficial because compared to using ASC or BIL for the "partial CHMs" that are only generated temporarily the use of LAZ will significantly lower the amount of data that need to be written to and then read back in again. However, if you have large disks and file system buffers then using BIL instead of LAZ may be overall faster as the CPU does not have to compress / decompress the temporarily stored data.

Other recent changes:

30 July 2016 -- las2las: correct naming of stateplanes when combining '-sp83 CA_I' with 'set_ogc_wkt'

29 July 2016 -- lasgrid, las2dem, lascanopy, lasoverlap: grids can be output as compressed LAZ points

28 July 2016 -- lasclip: new option '-donuts' to handle islands and lakes (based on winding order)

27 July 2016 -- lascontrol: new options '-cp_ignore_diff_above 1.5' '-cp_ignore_diff_below -0.5' 

26 July 2016 -- lascanopy: ability to use '-names' in '-loc' and '-lor' lists of circ/rect plots

21 July 2016 -- las2iso, lasboundary, las2shp, las2tin: output *.prj files for SHP file output

19 July 2016 -- las2las: fixed bug with '-target_survey_feet' not always working with '-cores 8'

18 July 2016 -- lasgrid, las2dem, lascanopy, lasoverlap: output *.prj files for ASC/BIL/FLT/XYZ

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

Regards,

Martin @rapidlasso