[Liblas-devel] liblas

[Howard Butler]

Martin,

I am writing you to give you an update of where things are and hope to  
persuade you to join the liblas-devel list so we can benefit from your  
expertise and experience.

The first developments I will mention are that we took the lastools  
stuff, imported it into subversion, and then added some automake, msvc  
projects, and msvc makefiles to it.  This can be found at http://liblas.org/browser/tags/original 
   (or http://liblas.org/svn/tags/original for the svn version).   
After polishing things a little bit, we started in on reworking the  
reader class to use a pimpl approach http://mail.hobu.net/pipermail/liblas-devel/2007-December/000008.html 
   We are currently in the process of fleshing out the pimpl-based  
reader.

Two other developers besides myself are working on the library  
(Mateusz Loskot and Phil Vachon).  We all are heavily involved with  
the GDAL http://www.gdal.org project, and we have various expertise in  
different areas of the project.  For liblas, Mateusz is focused on the  
C++ implementation, I am focused on C API development (and a Python  
API) and porting your utilities to use that, and Phil is focused on  
SAR-related usages.

We've been attempting to pull together as much LAS format-related  
stuff onto the wiki at liblas.org as we can in an attempt to congeal  
the format oriented stuff in one place.  All of the articles and code  
are so scattered that it is challenging for someone not initiated to  
figure out what to do and where to go.  Hopefully with enough linkage  
and information, the liblas wiki will end up being a highly ranked  
website and simple searches will point people to it and they can find  
what they are looking for.

Finally, I know you are an extremely busy academic (my wife is a  
professor, so I understand the lifestyle ;) ), but I would implore you  
to join the liblas-devel mailing list.  Your experience with the LAS  
specifications (and their sometimes lack of specificity) would be  
extremely helpful to us.  We are more software development-oriented  
folks, and while we can dig, scratch, and claw our way to LAS format  
zen, imparted experience from a LAS format zen master would be highly  
beneficial.  liblas is an opportunity for you to provide some minimal  
direction toward a gold-plated 2.0 version of your library.  Below is  
a list of things we would love some direction on:

- What should the API look like?  We know fairly well how we would use  
a LAS API from a direct data format translation perspective, but how  
would someone expect to use the library if they were building  
applications atop it directly?  Your experience with integrating  
lastools into your applications can provide us some direction here.   
Should we just make a straight port of what you outlined (plus some  
more sophisticated error handling, etc), or were there things you  
would have like to have had but didn't have the time to do (more  
convenience, syntactical sugar, alternative access methods, etc)?

- In the face of ambiguity from the 1.0 and 1.1 specifications, what  
choices are people typically making?  For example, scan angle rank is  
defined as unsigned byte from -90 to +90 in the 1.0 specification and  
as just unsigned byte in the 1.1 specification.  Does this mean it is  
still +90/-90 in 1.1, even though it is not clearly specified, is it  
merely a convention for 1.1, and so on.

- All three of us are very skeptical about the LAS 2.0 specification,  
and you had expressed some displeasure about it as well.  What are  
some things we can do at the library level with an eye toward  
supporting it at some point in the future?  Or rather, what things can  
we do to support the expected most common usages of 2.0 LAS data?  My  
feeling is that LAS 2.0 is so wide open that LAS 2.0 from one vendor  
is going to be different than LAS 2.0 from another.  What's your  
feeling on the subject?

A last related point is development specific.  If you are interested  
in participating from a software development perspective, please let  
me know, and I will provide you with a login that you can use on  
liblas.org to commit to the subversion repository and make additions/ 
changes on the wiki pages, file tickets, etc.

Thanks for your time, and we look forward to hearing from you.

Howard