Hamish wrote:
Mateusz:
Yes, it confirms what I've read in GRASS docs and Wiki pages,
that there is no direct support to ASPRS LAS format.
...
I'm willing to contribute a module for LAS read/write. However, I'm not
an experienced GRASS user nor developer, so I'll likely need to prepare
myself a little (read docs and code) before I can start. Means, I'm not
sure I can provide you with ready solution very soon.
...
The libLAS building follows well-known *nix patterns and there is
autotools-based builder. Optionally, users are provided with cmake
configuration as well as project files for Visual C++ 2005.
The library itself has no external dependencies.
Hi,
I don't claim to know anything about what libLAS does, so sorry if this
doesn't make sense. But if it is purely vector format I/O would it be
better to write it as a new format for GDAL's OGR and have grass access
it with v.in.ogr?
Hamish,
I agree that the LAS format is a vector format by data nature and
structure. However, considering how LiDAR clouds are usually processed
and analysed, they are closer to rasters and grids:
1. It's not uncommon to store millions of points in a single LAS file.
2. Mostly we are not interested in a single point feature but in
groups/areas of hundreds or thousands
3. A feature-oriented seems not very usable
Technically, there is no problem with translating LAS file to OGR
datasource and there is a prototype of appropriate tool [1] available,
but I'm not optimistic in its usability and *performance* in processing
of large sets of LiDAR data.
[1] http://liblas.org/svn/trunk/apps/las2ogr.cpp
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?
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.
Greetings
--
Mateusz Loskot
http://mateusz.loskot.net
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