[Liblas-devel] [LAStools] Re: set rgb with laslib

[Martin Isenburg]

Hello Pol,

attached is sample code that uses LASlib to read a LAS / LAZ file with
point type 0, 1, or 4, add RGB colors, and write a LAS / LAZ file with
point type 2, 3, or 5 respectively. This lasexample_add_rgb.cpp source code
has also been added as a new permanent example of LASlib use to the
./LAStools/LASlib/example folder and can be accessed via github here:

http://github.com/LAStools/LAStools/tree/master/LASlib

Regards,

Martin @rapidlasso

On Fri, Apr 8, 2016 at 1:02 PM, Pol Monsó Purtí <lluna.nova at gmail.com>
wrote:

> I was wrong.
>
> The init is not sufficient because the header itself stores the point data
> format and size.
>
> If I set them in a copy of the header that I then pass to the init, I get
> a segfault on the first point write, third writer. Probably because the
> size of the points is in fact incorrect.
>
> Anybody willing to weight in?...?
>
> On Tue, Apr 5, 2016 at 6:12 PM, Pol Monsó Purtí <lluna.nova at gmail.com>
> wrote:
>
>> Ok, it seems I should create a new point and call to init, as seen on the *writer
>> only* example.
>>
>> In my case, the output point data record format is 3, with a size of 34.
>>
>> Therefore:
>>
>>
>>   LASpoint p;
>>
>>   laspoint.init(&lasreader->header, PointDataFormatID_2, PointDataFormatSize, 0);
>>
>>
>> with 2 and 34. Is that correct? Do I have to manually change the header to activate have_rgb?
>>
>>
>> Is that the way to do this?
>>
>> Do I have to guarantee the existence of the LASpoint memory until the
>> close or just until the write? (effectively reusing it after each iteration)
>>
>> What happens if I call init on the LASpoint* of the reader?
>>
>> Cheers,
>>
>> Pol
>>
>> On Tue, Apr 5, 2016 at 5:27 PM, Pol Monsó Purtí <lluna.nova at gmail.com>
>> wrote:
>>
>>> Ok, it definetly has to do something about the header or the point type.
>>> If I take in a cloud with rgb I can change it and save it. And it does have
>>> the RGB12_LE writer in its vector.
>>>
>>> Now, how can I tell liblas to add this writer on the writer if it ain't
>>> there on the reader?
>>>
>>> On Tue, Apr 5, 2016 at 5:02 PM, Pol Monsó Purtí <lluna.nova at gmail.com>
>>> wrote:
>>>
>>>> I've debugged the application and the point p has the rgb, but I
>>>> couldn't find where it is written.
>>>>
>>>> It is probably at LASwriteItemRaw_POINT10_LE, which is the writer that
>>>> gets called from the writers vector. Does LAS 1.0 support color? If not,
>>>> how do I set the LAS specification?
>>>>
>>>> The input cloud is supposed to be las 1.2. I've added the following
>>>> line after the writing loop and before the close, so that I don't get the
>>>> npoints mismatch error:
>>>>
>>>> laswriter->update_header(&lasreader->header, TRUE);
>>>>
>>>>
>>>>
>>>>
>>>> Btw, I forget to mention that I'm on windows
>>>>
>>>> On Tue, Apr 5, 2016 at 4:53 PM, Pol Monsó Purtí <lluna.nova at gmail.com>
>>>> wrote:
>>>>
>>>>> I want to colorize a colorless las cloud, but I get only 0 as rgb. Is
>>>>> there a parameter that must be set (e.g. has_rgb)?
>>>>>
>>>>> I am currently doing the following:
>>>>>
>>>>>     LASreadOpener lasreadopener;
>>>>>
>>>>>   lasreadopener.set_file_name(infilename);
>>>>>
>>>>>   LASreader* lasreader = lasreadopener.open();
>>>>>
>>>>>
>>>>>   LASwriteOpener laswriteopener;
>>>>>
>>>>>   laswriteopener.set_file_name("test.las");
>>>>>
>>>>>   LASwriter* laswriter = laswriteopener.open(&lasreader->header);
>>>>>
>>>>>
>>>>> [...]
>>>>>
>>>>>
>>>>>   lasreader->seek(0);
>>>>>
>>>>>
>>>>>   U16 rgb[4];
>>>>>
>>>>>   U16 colur = 100;
>>>>>
>>>>>
>>>>>   for(int i = 0; i < npoints; i++)
>>>>>
>>>>>   {
>>>>>
>>>>>     lasreader->read_point();
>>>>>
>>>>>     LASpoint *p = &lasreader->point;
>>>>>
>>>>>     rgb[0] = colur;
>>>>>
>>>>>     rgb[1] = colur;
>>>>>
>>>>>     rgb[2] = colur;
>>>>>
>>>>>     rgb[3] = 0;
>>>>>
>>>>>     p->set_rgb(rgb);
>>>>>
>>>>>     laswriter->write_point(p);
>>>>>
>>>>>   }
>>>>>
>>>>>
>>>>>
>>>>>   I64 total_bytes = laswriter->close();
>>>>>
>>>>>   delete laswriter;
>>>>>
>>>>>
>>>>>   lasreader->close();
>>>>>
>>>>>   delete lasreader;
>>>>>
>>>>>
>>>>
>>>
>>
> --
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