use_orig_bb

[Susana Gonzalez]

Hi Martin,

Do you know if the parameter -use_orig_bb can be use in las2txt?

 

This is my line

las2txt.exe -i %LIDAR%\*.laz -keep_class 9 -use_orig_bb -odir %OUTLIDAR% -otxt -parse txyzr -sep comma -cores 20

 

And this is the error

ERROR: cannot understand argument ‘use_orig_bb’

 

Thanks

Susana

 

Susana Gonzalez - Forest Engineer, LiDAR Science

 

Interpine Group Ltd

DDI:  +64 7 350 3209 or Australia 0280113645 ext 722
Skype:        sugonar

Address :   99 Sala Street, PO Box 1209, Rotorua 3010, New Zealand
Website :   www.interpine.co.nz

 

Interpine Innovation is Shaping Today’s Forests with the Technology of Tomorrow

He rangahau tenei ra he hangarau apopo

 

[Martin Isenburg]

Hello Susana,

the parameter '-use_orig_bb' is special to those applications that input a *buffered* tile that was generated with on-the-fly buffering via '-buffered 25' either in by the current tool or by a (sequence of) previous tool that used '-remain_buffered' to keep writing those buffers also to disk. It is in particular important to use with las2dem and blast2dem to avoid artifacts along the tile boundary (or the similar '-use_tile_bb' when the buffers were created during tiling).  Although *all* points (including buffer points) are used to create the interpolating Delaunay TIN only the original tile bounding box ('orig_bb') is used to output the rasters in. For convenience it is also available in lasoverlap, lasgrid, and lascanopy but not needed as these simpler *binning* tools do not interpolate and therefore are not subject to tile boundary artifacts.

Currently it is not possible to remove the "on-the-fly" buffers that were store to a file "on-the-fly" but I will be introducing some functionality to do just that.

Regards.

Martin @rapidlasso

http://rapidlasso.com/2015/08/07/use-buffers-when-processing-lidar-in-tiles/

To remove the

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[Susana Gonzalez]

Hi Martin,

My goal is to extract the highest point in a cell grid of 3x3m within 500x500m tiles. Because 500m is not divisible by 3m, it is important to buffer the tiles as we don’t want to select a high point at the intersection of two tiles that is not the highest point in the 3x3m cell.

 

The first step is running lasthin to get the highest points inside of a grid cell of 3x3m.

 

lasthin.exe -i %INCDATA%\*.laz ^

       -drop_class 7 -step 3 -highest -classify_as 9 ^

        -odir %OUTLIDAR% -odix _ht -olaz ^

        -cores 20

 

And then, I extract the values by tile

 

las2txt.exe -i %OUTLIDAR%\1876500_5595500_hnom_d_ht.laz -inside_tile 1876500 5595500 500 -keep_class 9 -odir %OUTLIDAR% -otxt -parse xyz -ocut 9 -odix xyz -sep comma

 

The txt file with the highest points looks like the image below over a grid cell of 3x3m (the fish net was created with same starting coordinates as the low left of the tile)

 

Why am I getting sometimes more than one high point in a cell and sometimes none?

 

Thank you for your time

Susana

[Martin Isenburg]

Hello Susana,

it appears that the grid used by lasthin and the grid you are overlaying are not the same. There is a translation between the two. I am not sure where your "red" grid comes from but the image clearly shows that it is not the same grid as that which lasthin is using.

Regards,

Martin @rapidlasso

On Fri, Apr 21, 2017 at 6:33 AM, Susana Gonzalez <susana....@interpine.nz> wrote:

Hi Martin,

My goal is to extract the highest point in a cell grid of 3x3m within 500x500m tiles. Because 500m is not divisible by 3m, it is important to buffer the tiles as we don’t want to select a high point at the intersection of two tiles that is not the highest point in the 3x3m cell.

[Sam Hackett]

Hi Martin,

Regarding your comment above from 21/04/2017 "Currently it is not possible to remove the "on-the-fly" buffers that were store to a file "on-the-fly" but I will be introducing some functionality to do just that."

I have just experimented with applying on-the-fly buffers as part of lasnoise, and then later removing them using lastile and it seems to return the tile back to the original bounding box.  Is that an intended workflow from development since 2017?  Or perhaps a latent functionality for removing OTF buffers?  In my example I have custom predefined tiles which I want to respect through my workflow.

APPLY BUFFERS

lasnoise -i %InputDir%\*.laz ^

-cores %Cores% ^

-ignore_class 7 ^

-buffered 5 -remain_buffered ^

-change_classification_from_to 6 19 ^

-step %step% -isolated %isolated% ^

-classify_as 18 ^

-odir %OutputDir% ^

-olaz

REMOVE BUFFERS

lastile -i %InputDir%\*.laz ^

-cores %Cores% ^

-remove_buffer ^

-odir %OutputDir% ^

-olaz

Regards

Sam

[Martin Isenburg]

Hello Sam,

Yes. This functionality had been added a long time ago and works as you describe.

http://rapidlasso.com/lastile

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

The tool lastile with the option '-remove_buffer' can do both, remove buffers created by lastile and remove buffers created via on-the-fly buffering where tiles '-remained_buffered'. Both ways of operating are described with a small example in this blog post:

https://rapidlasso.com/2015/08/07/use-buffers-when-processing-lidar-in-tiles/

Regards,

Martin @rapidlasso

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