Floating point round off in libLAS Python API

Question

I am trying to use libLAS Python API to write point data sets to *.las file. But I am experiencing some problems with the floats values being rounded off

>>> from liblas import point
>>> pt=point.Point()
>>> pt.x=2.323
>>> pt.x
2.0
>>>

If I set the pt.raw_x instead of pt.x I don't see the rounding off problem but no las file is written.

>>> pt.raw_x=2.323
>>> pt.raw_x
2.323

I am not sure what am I missing. I would appreciate any help with this.

Answer 1

With some pointer from mloskot I figured out solution to the issue. For future reference and benefit for other libLAS newbies I am posting below a small test code I wrote. It uses the sample las file srs.las from libLAS website, modifies the z values and writes it out to a new las file.

#!/usr/bin/python
import os,string,glob,re,gdal,sys
from liblas import file
from liblas import header
from liblas import point
from datetime import datetime

hout=header.Header()

# Define the las file name
infile="srs.las"

# Create the output las filename
inarr=infile.split('.')
outfil=inarr[0]+"_newnorm.las"

# Open the input las file
l=file.File(infile,mode='r')

# Get the header information
hin=l.header

# Now let's copy some of the header information from infile to outfile
hout.major_version = hin.major_version
hout.minor_version = hin.minor_version
hout.guid = hin.guid
hout.system_id = hin.system_id
hout.software_id = "libLAS Python API"
date = datetime(2014,03,17)
hout.date = date 
hout.offset = hin.offset
hout.scale = hin.scale
hout.compressed = hin.compressed
hout.count = hin.count
hout.data_format_id = hin.data_format_id
hout.dataformat_id = hin.dataformat_id
hout.data_offset = hin.data_offset
hout.point_return_count = hin.point_return_count
hout.srs = hin.srs
hout.version = hin.version
hout.min = hin.min
hout.max = hin.max

print "Number of points: "+str(len(l))

lout=file.File(outfil,mode='w',header=hout)
for p in l:
    x=float(p.x)
    y=float(p.y)
    z=float(p.z)

    # Modify z value
    znorm = z-1

    pt=point.Point()
    pt.set_header(hout)

    pt.x=float(p.x)
    pt.y=float(p.y)
    pt.z=float(znorm)

    pt.intensity = p.intensity
    pt.number_of_returns = pt.number_of_returns
    pt.point_source_id = p.point_source_id
    pt.raw_time = p.raw_time
    pt.return_number = p.return_number
    pt.scan_angle = p.scan_angle
    pt.scan_direction = p.scan_direction
    pt.scan_flags = p.scan_flags
    pt.classification = p.classification
    pt.color = p.color
    pt.flightline_edge = p.flightline_edge

    print "Writing  to output las file"
    lout.write(pt)

l.close()
lout.close()