[GRASS-user] LiDAR LAS import

[Rebecca Bennett]

Hello,

Just trying to install GRASS 7 on Ubuntu 10.04 to try out the las import functions but I'm getting error messages during the configure that it is unable to find the liblas library, however the liblas library is installed in usr/bin/lib/ so I'm a bit puzzled...

Did anyone else get stuck here or am I missing something obvious?

Thanks for reading,
Rebecca




>________________________________
>From: Markus Metz <markus.metz.giswork at googlemail.com>
>To: Hamish <hamish_b at yahoo.com>
>Cc: grass-user <grass-user at lists.osgeo.org>; GRASS developers list <grass-dev at lists.osgeo.org>
>Sent: Wednesday, 25 May 2011, 12:48
>Subject: Re: [GRASS-user] LiDAR LAS import
>
>On Wed, May 25, 2011 at 12:16 PM, Hamish <hamish_b at yahoo.com> wrote:
>> Markus Metz wrote:
>>> Hi all,
>>>
>>> GRASS 7 has a new module v.in.lidar for importing LiDAR LAS files
>>> (*.las or *.laz). The LAS file format is commonly used for storing
>>> LiDAR point clouds, but is unfortunately not supported by OGR.
>>> v.in.lidar uses the libLAS library [0] and is only compiled if the
>>> libLAS library is present.
>>>
>>> I chose to use the library instead of writing a custom LAS reading
>>> interface because the current LAS library version 1.6.1 is stable,
>>> supports LAS file versions 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, each of
>>> which can store LiDAR points in up to 5 different point formats. The
>>> user and the interface do not need to know the file version and point
>>> format of a given file, all that is conveniently handled by the libLAS
>>> library in the background. The library has Large File Support (LFS)
>>> and is well tested on different platforms, also with different
>>> endian-ness. This functionality is not that easy to replicate.
>>>
>>> You will need to get the libLAS library and configure GRASS 7 with
>>> --with-liblas in order to have the module available. Please test!
>>>
>>> Markus M
>>>
>>> [0] http://www.liblas.org
>>
>>
>> neat! any time trials to say how much faster it is than piping
>>  las2txt | v.in.ascii
>> ?
>
>Note that las2txt does NOT apply scale and offset to x,y,z, this would
>need to be done afterwards in order to obtain correct coordinates.
>Therefore the output of las2txt | v.in.ascii with the sample las file
>I used is incorrect.
>
>I discovered a bug in v.in.ascii: from a point file with | as field
>separator like
>
>1|2|3||5|6
>
>only the first 3 columns will be imported because column 4 is empty
>which means that columns 5 and 6 are skipped.
>
>v.in.lidar is a notch faster than las2txt | v.in.ascii. And easier to use...
>Speed comparisons:
>
># sample las file with 1,287,775 points
>
># with table and topology
>time las2txt -i points.las --stdout --parse xyztinrcCpedRGBau
>--delimiter "|" | v.in.ascii in=- out=points_ascii -z x=1 y=2 z=3 --o
>
>real    6m34.430s
>user    4m57.530s
>sys    2m3.693s
>
>time v.in.lidar in=points.las out=points_las -o --o
>
>real    6m13.823s
>user    4m32.061s
>sys    2m1.068s
>
>
># without table, with topology
>time las2txt -i points.las --stdout --parse xyz --delimiter "|" |
>v.in.ascii in=- out=points_ascii -zt x=1 y=2 z=3 --o
>
>real    1m53.578s
>user    1m47.032s
>sys    0m9.238s
>
>time v.in.lidar in=points.las out=points_las -ot --o
>
>real    1m44.876s
>user    1m34.450s
>sys    0m8.488s
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