[GRASS-dev] Announcing libLAS

[Hamish]

> > Hamish wrote:
> >> Mateusz:
> > Hamish wrote:
> >> Or is the dataset size/model such that it is better to directly
> >> import/process it in GRASS using fast C modules as a front end to
> >> the lib?
Mateusz:
> > Yes, this is my understanding. As a note of explanation, I'm not a  
> > very experienced user of LiDAR data, so I'm not able to explain the  
> > nature of processing and analysis of "huge clouds of points"
> > datasets. However, I understand that speed and performance is a
> > critical factor.
Helena:
> Hamish - what Mateusz is saying is right - in fact the first thing I  
> had in mind was to ask both of you to see how to make r.in.xyz read  
> the LAS data directly (and maybe even run several of the statistics  
> at once, if possible).

Ok, I think a new -r flag could be added to r.in.xyz to tell the input=
file to expect a LAS file instead of a text file. (I don't like -l, it is
too close to -1 in some fonts)

I really won't have any time in the few months to work on this (or much
else for that matter, no matter how interesting), but I would be
supportive of it happening.


> The data sets usually have millions of points (you may remember the
> email about my colleague running r.in.xyz with 1.5 billion points)
> so skipping the ascii conversion may help quite a bit.

I didn't remember that but am glad to hear it (again). (thanks to those
who helped fix the LFS stuff)

> However, there are applications when it is useful to import the data  
> as vector points (at least some smaller data sets or subsets).

if there is a LAS->ASCII.csv tool somewhere, and the LAS data is only
point data, then the job is already done for that I think. No point
introducing the overheads of SimpleFeatures etc., just go direct.

> OGR

I would be happy to hand the vector/raster output question over to the
LIDAR users, as I'm not sure myself what your final output needs are.
e.g. what's the next step after import? v.surf.rst? r.univar?
thresholding?


Hamish



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