hello howard,
i agree with everything howard says. and i think that we can remedy all
those things with LAS 2.0. i got the following idea from talking to
someone at the IMLF showfloor (it was not my idea ... i stole it but i
personally think it's brilliant at the moment but you may convince me
otherwise):
make each point attribute a separate file. hence a "LAS file" is really
a "LAS directory". then the presence of the file with the right name
(e.g. "x", "y", "z", "rgb" ... determines the composition of the points
(rather than a point format in the header).
C:\released_code\lastools\data>dir serpent_mount_las
Directory of C:\released_code\lastools\serpent_mount_las
02/04/2010 11:24 PM <DIR> .
02/04/2010 11:24 PM <DIR> ..
01/27/2009 11:55 PM 227 header
01/27/2009 11:55 PM 5,966,832 x
01/27/2009 11:55 PM 5,966,832 y
01/27/2009 11:55 PM 5,966,833 z
01/27/2009 11:55 PM 2,983,416 r
01/27/2009 11:55 PM 2,983,416 g
01/27/2009 11:55 PM 2,983,416 b
7 File(s)
2 Dir(s) 3,245,469,696 bytes free
this takes away all the fluff. makes it super extendable. allow for more
complex data types to be easily added (e.g. doubles, velocity vectors, ...).
and when you "classify" the LIDAR points you can just create a
"classification" file without having to touch gigabytes of data just to
re-write the classification entry of every point.
of course ... the disadvantage will be the multiple files overhead. but
assuming we have spatial indexing as well we can get away with one very
LARGE las files instead of tons of smaller las files, thereby lowering
the total number of files again,
what do you think? feel free to set me straight now ... it was not my
idea in the first place so you can't hurt my feelings. (-:
martin
--
scientist in data visualization facilitator for sustainable communities
http://downtownfarm.net 925-456-4461 http://www.cs.unc.edu/~isenburg/
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