[Liblas-devel] Clipping

[Giglierano, James [DNR]]

Actually, we have seen regular cases of sunlight reflecting off water
surfaces to the lidar sensor.  Since the sunlight is always on, it gives
a false elevation of the airplane's height.  These are usually filtered
out for the bare earth classification by the vendor, but they still
appear in the first return data, maybe others.  Unless you are aware
that this happens, it can be disconcerting when it first appears.  A
height filter might be useful, or something to catch and remove outliers
such as this.

-----Original Message-----
From: liblas-devel-bounces at mail.hobu.net
[mailto:liblas-devel-bounces at mail.hobu.net] On Behalf Of Mateusz Loskot
Sent: Wednesday, April 09, 2008 11:24 AM
To: Liblas-devel at mail.hobu.net
Subject: Re: [Liblas-devel] Clipping

Howard Butler wrote:
> 
> On Apr 9, 2008, at 10:32 AM, Mateusz Loskot wrote:
>> Hi,
>>
>> Do we have a tool that can clip LAS file to given extent of XYZ
pairs?
>> I imagine to have something like:
>>
>> las2las --min X1 Y1 Z1 --max X2 Y2 Z2 --in file.las --out clipped.las
> 
> Yep, but it only clips on x and y, not z.  I'm not sure you would want

> to clip z's out, but that could be easily added.
> 
> http://liblas.org/browser/trunk/apps/las2las.c#L55
> 
> las2las -i file.las --clip X1 Y1 X2 Y2 --out clipped.las

Hobu,

That's exactlu what I was looking for. You are right, clipping by Z 
value is usually not very useful.

Cheers
-- 
Mateusz Loskot
http://mateusz.loskot.net
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