[Liblas-devel] GPS time and intensity?

[Jason Woolard]

Hi,

The time update seems to be working fine with my files but I was able to 
raise an error with the sample Serpent_Mound_Model_LAS_Data.las file 
from Martin's site.

The error is:

File "C:\Python25\lib\site-packages\liblas\point.py", line 185, in get_time
    return datetime.datetime(lt[0],lt[1],lt[2],lt[3],lt[4],lt[5],ms)
ValueError: microsecond must be in 0..999999

The Serpent LAS sample does have data to 6 decimal places while my files 
only have data to three places. Other than that the files seem to be the 
same.

Howard Butler wrote:
>
> On Oct 13, 2008, at 1:13 PM, Jason Woolard wrote:
>>
>> On the GPS time issue, I think it's definitely important to have more 
>> precision than the nearest second. The GPS/Inertial or trajectory 
>> data is usually measured at ~200 Hz and one of the useful things 
>> about having the GPS time stamp is the ability to match up a 
>> particular pulse with the corresponding time in the vehicle 
>> trajectory or scanner angle data. Commercial topographic lidar 
>> systems are now pulsing at 100 kHz + so having the times rounded to a 
>> second would mean you could potentially have 100,000 points or more 
>> with identical times. In addition, the time stamp will be even more 
>> important as laser waveform data becomes more mainstream.
>
> Jason,
>
> After thinking about this a bit, I think the problem is just related 
> to the Python bindings throwing out the fractional seconds.  I took a 
> crack at fixing this in the Python bindings
>
> http://liblas.org/changeset/945
>
> Here's a ticked to track the changes:
>
> http://liblas.org/ticket/83
>
> If you could use subversion to build from trunk or the 1.0 branch and 
> test that things are behaving correctly, it would be greatly appreciated.
>
> Thanks,
>
> Howard