[Liblas-devel] GPS Time and inverted height

[Howard Butler]

Ah, maybe I misinterpreted Q1.  Yes, libLAS' las2las can change the point format of the LAS file to support storing of time values.  It can't, however, put "fake" or artificial time values in that slot other than 0.0 as Martin demonstrates.

Howard

On Jun 15, 2011, at 8:51 AM, Martin Isenburg wrote:

> hi,
> 
> the las2las version from LAStools [*] can do both Q1 and Q2.
> 
> for Q1 you can set a gps-time of 0.0 for each point with
> 
> las2las -i lasformat0.las -o lasformat1.las  -point_type 1
> 
> or for LAS points with RGB values
> 
> las2las -i lasformat2.las -o lasformat3.las  -point_type 3
> 
> for Q2 you can invert the height with
> 
> las2las -i lidar.las -o lidar_inverted.las -scale_z -1.0
> 
> cheers,
> 
> martin @lastools
> 
> [*] http://www.cs.unc.edu/~isenburg/lastools
> 
> On Wed, Jun 15, 2011 at 6:18 AM, Howard Butler <hobu.inc at gmail.com> wrote:
> On Jun 15, 2011, at 4:33 AM, Julian Olszewski wrote:
> 
> > Sorry for asking two questions within the same thread.
> 
> No problem.
> 
> > Q1: Is there any way to populate a las file with "fake" GPS Time.
> 
> Not with libLAS at this time.  las2las can only do translation on XYZ values at this point.  You could do it yourself using the Python bindings and a little bit of scripting (it would be much slower, of course).
> 
> > The software I use require GPS Time - it's mandatory otherwise I won't be able to load the data
> 
> Which software is this?  It would seem that it could do the faking itself if it didn't find time values.
> 
> > Q2: Can I invert the height or multiply by -1?
> 
> See above.
> 
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