new lascanopy.exe computes basic raster metrics for forestry applications

[Martin Isenburg]

hello,

as announced during my keynote at SilviLaser in Vancouver, the first
version of the new lascanopy.exe tool has been added to the latest
LAStools distribution (version 120930). For now it only computes a few
basic forestry raster metrics ... but a start was made. I am taking
requests for other, similar metrics to be added assuming they are
generic enough to be of interest to a larger number of foresters. Here
is the current line up:

-min : minimum value (heights > t)
-max : maximum value (heights > t)
-avg : mean of values (heights > t)
-std : standard deviation of values (heights > t)
-p 1 : 1th percentile (heights > t)
-p 5 : 5th percentile (heights > t)
-p 10 : 10th percentile (heights > t)
-p 25 : 25th percentile (heights > t)
...
-p 99 : 99th percentile (heights > t)

where t is a user-defined threshold of height above ground to consider
vegetation. The default is 1.37m, which equals breast height. Detailed
instructions can be at the end of this message and also online:

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

Cheers,

Martin @rapidlasso

****************************************************************

lascanopy:

This tool reads LiDAR from LAS/LAZ/BIN/SHP/QFIT/ASCII, computes
popular forestry metrics, and grids them onto a raster. A very
important parameter is '-step n' that specifies the n x n area
of LiDAR points that are gridded on one raster (or pixel). The
default of step is 20. The output can be either in BIL, ASC, IMG,
TIF, XYZ, FLT, or DTM format.

The tool can concurrently compute a number height percentiles
('-p 5 10 25 50 75 90'), the '-min', the '-max', the '-avg', and
the '-std' of all heights above the cutoff that is usually at
breast height. The default is 1.37 and it can be changed with
the option '-height_cutoff 0.75'.

By default the generated raster spans the extend of the header
bounding box. You can use the bounding box of the tile with
'-use_tile_bb' (which only makes sense if the LAS/LAZ file was
generated using lastile) or the original bounding box in case
of a buffered tile with '-use_orig_bb' (which only makes sense
if the input has an on-the-fly buffer aka '-buffered 50'). The
extend can also be defined by setting '-ll min_x min_y' plus
'-ncols 512' and '-nrows 512'.

It is very important (at the moment) that the input files are
height normalized, meaning that the z coordinate of each point
corresponds to the height above ground and not the elevation of
the point. With 'lasheight -i in.laz -replace_z -i out.laz' you
can height-normalize a ground classified LiDAR file.

Let me know which other metrics you would like to see ...

Please license from martin....@gmail.com to use lascanopy
commercially.

For updates check the website or join the LAStools mailing list.

http://lastools.org/
http://groups.google.com/group/lastools/
http://twitter.com/lastools/
http://facebook.com/lastools/
http://linkedin.com/groups?gid=4408378

Martin @lastools

****************************************************************

example usage:

>> lascanopy -i *.las -min -max -avg

for each *.las files and for all height above 1.37 it computes
the minimum, maximum, and average value from all points that fall
into cells of size 20 by 20 and stores the resulting grid in ASC
format using the endings '_min.asc', '_max.asc', '_avg.asc'.

>> lascanopy -i lidar*.laz -merged -p 20 40 60 80 -step 10 -o dem.bil

merges the points of all files that match the wildcard lidar*.laz
on-the-fly into one file and computes for all heights above 1.37
the 20th, 40th, 60th, and 80th percentile for 10 by 10 grid cells
and stores the resulting rasters in BIL format using the endings
'_p20.bil', '_p40.bil', '_p60.bil', and '_p80.bil'.

other commandline arguments are

-mem : amount of main memory to use in MB (500 -
2000) [default: 500]
-temp_files : base file name for temp files (example: E:
\tmp)
-step 2 : raster with stepsize 2 [default: 1]
-nrows 512 : raster at most 512 rows
-ncols 512 : raster at most 512 columns
-ll 300000 600000 : start rastering at these lower left x and y
coordinates
-nodata 9999 : use 9999 as the nodata value in the BIL / ASC
format
-max : for each grid cell keep highest value
-min : for each grid cell keep lowest value
-avg : for each grid cell compute average
-std : for each grid cell compute standard deviation
-utm 12T : use UTM zone 12T to spatially georeference
the raster
-sp83 CO_S : use the NAD83 Colorado South state plane for
georeferencing
-sp27 SC_N : use the NAD27 South Carolina North state
plane
-longlat : geometric coordinates in longitude/latitude
order
-latlong : geometric coordinates in latitude/longitude
order
-wgs84 : use the WGS-84 ellipsoid
-wgs72 : use the WGS-72 ellipsoid
-nad83 : use the NAD83 ellipsoid
-nad27 : use the NAD27 ellipsoid
-survey_feet : use survey feet
-feet : use feet
-meter : use meter
-elevation_surveyfeet : use survey feet for elevation
-elevation_feet : use feet for elevation
-elevation_meter : use meter for elevation
-tiling_ns crater 500 : create a tiling of DEMs named crater with
tiles of size 500
-tm 609601.22 0.0 meter 33.75 -79 0.99996
-transverse_mercator 1804461.942257 0.0 feet 0.8203047 -2.1089395
0.99996
-lcc 609601.22 0.0 meter 33.75 -79 34.33333 36.16666
-lambert_conic_conformal 1640416.666667 0.0 surveyfeet 47.000000
-120.833333 47.50 48.733333
-ellipsoid 23 : use the WGS-84 ellipsoid (do -ellipsoid -1
for a list)

for more info:

C:\lastools\bin>lascanopy -h
Filter points based on their coordinates.
-clip_tile 631000 4834000 1000 (ll_x ll_y size)
-clip_circle 630250.00 4834750.00 100 (x y radius)
-clip_box 620000 4830000 100 621000 4831000 200 (min_x min_y min_z
max_x max_y max_z)
-clip 630000 4834000 631000 4836000 (min_x min_y max_x max_y)
-clip_x_below 630000.50 (min_x)
-clip_y_below 4834500.25 (min_y)
-clip_x_above 630500.50 (max_x)
-clip_y_above 4836000.75 (max_y)
-clip_z 11.125 130.725 (min_z, max_z)
-clip_z_below 11.125 (min_z)
-clip_z_above 130.725 (max_z)
Filter points based on their return number.
-first_only -keep_first -drop_first
-last_only -keep_last -drop_last
-keep_middle -drop_middle
-keep_return 1 2 3
-drop_return 3 4
-keep_single -drop_single
-keep_double -drop_double
-keep_triple -drop_triple
-keep_quadruple -drop_quadruple
-keep_quintuple -drop_quintuple
Filter points based on the scanline flags.
-drop_scan_direction 0
-scan_direction_change_only
-edge_of_flight_line_only
Filter points based on their intensity.
-keep_intensity 20 380
-drop_intensity_below 20
-drop_intensity_above 380
-drop_intensity_between 4000 5000
Filter points based on their classification.
-keep_class 1 3 7
-drop_class 4 2
-drop_synthetic -keep_synthetic
-drop_keypoint -keep_keypoint
-drop_withheld -keep_withheld
Filter points based on their user data.
-keep_user_data 1
-drop_user_data 255
-keep_user_data_between 10 20
-drop_user_data_below 1
-drop_user_data_above 100
-drop_user_data_between 10 40
Filter points based on their point source ID.
-keep_point_source 3
-keep_point_source_between 2 6
-drop_point_source 27
-drop_point_source_below 6
-drop_point_source_above 15
-drop_point_source_between 17 21
Filter points based on their scan angle.
-keep_scan_angle -15 15
-drop_abs_scan_angle_above 15
-drop_scan_angle_below -15
-drop_scan_angle_above 15
-drop_scan_angle_between -25 -23
Filter points based on their gps time.
-keep_gps_time 11.125 130.725
-drop_gps_time_below 11.125
-drop_gps_time_above 130.725
-drop_gps_time_between 22.0 48.0
Filter points based on their wavepacket.
-keep_wavepacket 1 2
-drop_wavepacket 0
Filter points with simple thinning.
-keep_every_nth 2
-keep_random_fraction 0.1
-thin_with_grid 1.0
Transform coordinates.
-translate_x -2.5
-scale_z 0.3048
-rotate_xy 15.0 620000 4100000 (angle + origin)
-translate_xyz 0.5 0.5 0
-translate_then_scale_y -0.5 1.001
-clamp_z_below 70.5
-clamp_z 70.5 72.5
Transform raw xyz integers.
-translate_raw_z 20
-translate_raw_xyz 1 1 0
-clamp_raw_z 500 800
Transform intensity.
-scale_intensity 2.5
-translate_intensity 50
-translate_then_scale_intensity 0.5 3.1
Transform scan_angle.
-scale_scan_angle 1.944445
-translate_scan_angle -5
-translate_then_scale_scan_angle -0.5 2.1
Change the return number or return count of points.
-repair_zero_returns
-set_return_number 1
-change_return_number_from_to 2 1
-set_number_of_returns 2
-change_number_of_returns_from_to 0 2
Modify the classification.
-set_classification 2
-change_classification_from_to 2 4
Modify the user data.
-set_user_data 0
-change_user_data_from_to 23 26
Modify the point source ID.
-set_point_source 500
-change_point_source_from_to 1023 1024
Transform gps_time.
-translate_gps_time 40.50
-adjusted_to_week
-week_to_adjusted 1671
Transform RGB colors.
-scale_rgb_down (by 256)
-scale_rgb_up (by 256)
Supported LAS Inputs
-i lidar.las
-i lidar.laz
-i lidar1.las lidar2.las lidar3.las -merged
-i *.las - merged
-i flight0??.laz flight1??.laz
-i terrasolid.bin
-i esri.shp
-i nasa.qi
-i lidar.txt -iparse xyzti -iskip 2 (on-the-fly from ASCII)
-i lidar.txt -iparse xyzi -itranslate_intensity 1024
-lof file_list.txt
-stdin (pipe from stdin)
-rescale 0.01 0.01 0.001
-rescale_xy 0.01 0.01
-rescale_z 0.01
-reoffset 600000 4000000 0
Supported Raster Outputs
-o dtm.asc
-o dsm.bil
-o canopy.flt
-o dtm.dtm
-o density.xyz
-o intensity.img
-o hillshade.png
-o slope.tif
-o false_color.jpg
-oasc -obil -oflt -oimg -opng -odtm -otif -ojpg -oxyz -nil
-odir C:\data\hillshade (specify output directory)
-odix _small (specify file name appendix)
-ocut 2 (cut the last two characters from name)
LAStools (by martin....@gmail.com) version 120914 (unlicensed)
usage:
lascanopy -i *.las -max -avg
lascanopy -i *.laz -p 1 5 10 25 50 75 90 95 99
lascanopy -i *.laz -merged -max -avg -p 20 40 60 80 -o merged.dtm
lascanopy -h

---------------

if you find bugs let me (martin....@gmail.com) know

[Ty Kennedy-Bowdoin]

This is a great tool! One small issue...

when I run:

lascanopy -i first\tile*.laz -o test -otif -odir tiff -avg -step 100 -nodata -9999 -merged

the resulting file doesn't have a .tif ending and does have _avg added. This works normally if I dont use -merged, so the problem might be there. I have tried a few iterations of naming and I never get a tif ending with -merged. 

am I missing something?

thanks,

Ty

--
Download LAStools at
http://lastools.org/
Visit the LAStools group at
http://groups.google.com/group/lastools/
Be social with LAStools at
http://www.facebook.com/LAStools
http://www.twitter.com/LAStools

--
Ty Kennedy-Bowdoin
Carnegie Institution for Science
260 Panama St.
Stanford, CA 94305
USA
+1 831 227-3885
Skype: Ty.bowdoin

[Olli Pihlapuro]

Hi,

I am getting unexpected results with percentile heights.
I expect these commands to have somehow similar results

lascanopy -i *.las -p 50 -height_cutoff 0.1 -step 10 -otif
lascanopy -i *.las -avg -height_cutoff 0.1 -step 10 -otif

but the percentile output is mostly "no data" with some edge effects.
I have tried different output formats and command line examples from
the readme file,
but the results are always the same
Both outputs attached.

You asked requests for some metrics to be added, I think vegetation
index raster might have some value in it.
Calculation itself is easy, number of vegetation hits / (number of
vegetation hits + number of ground hits) in given cell area, but I
haven't found a way to do that with current LAStools.

Thanks,
Olli



2012/9/30 Martin Isenburg <martin....@gmail.com>:

[Martin Isenburg]

Hello,

a few bugs from the initial lascanopy.exe were fixed and a new option
was added in the LAStools release from today (version 121127). The
lascanopy.exe tool can also concurrently compute several height count
rasters. The option '-c 0.5 2 4 10 50', for example, would compute
four height count rasters for heights falling into these intervals:
[0.5, 2), [2, 4), [4, 10), [10, 50).

In addition two bugs have been fixed in las2dem with the release of
today (version 121127). One caused long single-core batch runs to
slowly run out of memory due to a missing 'free()' command for a
'malloc()' of some memory. The other was extremely rare and was
reported just last week for the first time in the long history of
las2dem.exe. This bug affected all raster writing LAStools - namely
las2dem, lascanopy, lasgrid, lasoverlap, and blast2dem - and while
extremely extremely rare ... it's nice to know it's dead now.

Cheers,

Martin @rapidlasso

On Oct 19, 3:35 am, Olli Pihlapuro <opihl...@gmail.com> wrote:
> Hi,
>
> I am getting unexpected results with percentile heights.
> I expect these commands to have somehow similar results
>
> lascanopy -i *.las -p 50 -height_cutoff 0.1 -step 10 -otif
> lascanopy -i *.las -avg  -height_cutoff 0.1 -step 10 -otif
>
> but the percentile output is mostly "no data" with some edge effects.
> I have tried different output formats and command line examples from
> the readme file,
> but the results are always the same
> Both outputs attached.
>
> You asked requests for some metrics to be added, I think vegetation
> index raster might have some value in it.
> Calculation itself is easy, number of vegetation hits / (number of
> vegetation hits + number of ground hits) in given cell area, but I
> haven't found a way to do that with current LAStools.
>
> Thanks,
> Olli
>

> 2012/9/30 Martin Isenburg <martin.isenb...@gmail.com>:

> >   Please license from martin.isenb...@gmail.com to use lascanopy

> ...
>
> read more »
>
>  out0015_avg.tif
> 5KViewDownload
>
>  out0015_p50.tif
> 1KViewDownload

[Ty Kennedy-Bowdoin]

Martin,

This is a great function! I use something similar outside of lastools, and this may replace it.  A few additions that I would be very excited about:

1. the number points at each height  increment as a percentage of the total count in that pixel.  
   
2. a way to set the heights by increment from the cutoff to max. For example: '-increment 1' would calculate rasters at all heights between the cutoff and max for the entire normalized height file with an increment of 1m.
3. a multiband raster output- it would be nice to make all of these rasters into one clean output with the bands ordered b1 (cutoff)...bn(max)

Thanks for adding this feature, I think it will be very useful to many of us!

Ty

--
Download LAStools at
http://lastools.org/
Visit the LAStools group at
http://groups.google.com/group/lastools/
Be social with LAStools at
http://www.facebook.com/LAStools
http://www.twitter.com/LAStools