Good idea.  I think it will work.

 I'll implement that.

Thanks,
Hongwei


On Fri, Jan 6, 2012 at 4:10 PM, Howard Butler <[email protected]> wrote:
> If you do work to add this, you'll probably just need to add a seek() method 
> to the liblas::Writer class (and underlying implementation classes) that 
> positions the stream.  After that liblas::Writer::WritePoint() should 
> overwrite the data, though you may want to do some header checks to make sure 
> that the size in bytes of the point is the same as the size in bytes that the 
> file is expecting -- otherwise you'd start clobbering data.
>
> On Jan 6, 2012, at 2:36 PM, Hongwei Shen wrote:
>
>> Thank you for the answer, Howard.
>>
>> I'll check if I can add this support.
>>
>> Thanks,
>> Hongwei
>>
>>
>> On Fri, Jan 6, 2012 at 1:47 PM, Howard Butler <[email protected]> wrote:
>>>
>>> On Jan 6, 2012, at 12:16 PM, Hongwei Shen wrote:
>>>
>>>> Hello,
>>>>
>>>> The scenario is: the user opens a large Lidar file,  changes the
>>>> classification labels of a small number of points and save the changes
>>>> to the file.  When the Lidar file is huge, it is time-consuming to
>>>> output all the points. So it would be better if only the modified
>>>> points are updated in the Lidar file.  According to my understanding
>>>> now, Liblas needs to save  all the (changed and unchanged) points to a
>>>> new Lidar file. That's because Liblas can open a Lidar file either in
>>>> read-only mode or write-only mode, but not in read-write mode.
>>>>
>>>> Do I understand correctly?  Is there a way to only update some points?
>>>
>>>
>>> Yes, your understanding is correct. libLAS does not support in-place 
>>> updating of points.
>>>
>>> Howard
>>>
>
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