[Liblas-devel] LAS I/O and header question?

[Jason Woolard]

hi everyone,

I just got the library running in Python and I have a quick question for 
anyone out there. I've had success with the tutorial but a little 
trouble implementing some things. Just for starters I was trying to read 
through a LAS file, extract some points by elevation, update the header 
and write a new file out. I can extract the points I want or update the 
header I just can make them work together. I just joined the group a few 
days ago so I apologize if I'm missing something obvious here.

Here is the version of the script that will return the points but not 
update the header. I can modify this slightly based on the tutorial to 
return a modified header but the data points seem to be in a different 
coord system or have a funky scale factor applied.

Thanks in advance for any insight.

import os
from liblas import file
from liblas import point
from liblas import header

infile = file.File('C:\\liblas_test\\debug.las',mode='r')
outfile = file.File('C:\\liblas_test\\outlas.las',mode='w',header = 
infile.header)

#Update records in LAS file

outfile.header.set_dataformatid(1)
outfile.header.set_majorversion(1)
outfile.header.set_minorversion(0)
outfile.header.set_softwareid('Test')

for p in infile:

    #Locate and write points less than or equal to -24 meters in elev
    if p.z <= -24.00:
        pt = liblas.point.Point()
        pt.x = p.x
        pt.y = p.y
        pt.z = p.z

        outfile.write(pt)

infile.close()
outfile.close()