[pdal] How to get las header info?

[Andrew Bell]

LasReader provides the header() function that returns a reference to the
LasHeader.

On Tue, Jul 5, 2022 at 10:50 AM Peder Axensten <Peder.Axensten at slu.se>
wrote:

> Hello again,
>
> I tried the 2.4.2 version and I notice that the copy and move constructors
> (and operators) are now implemented.
> But pdal::LasHeader now lacks the default constructor, so this code still
> does not work:
>
>     pdal::LasHeader get_header( const std::filesystem::path & path_ ) {
>         pdal::LasHeader          header{};   // error: no matching
> constructor for initialization of 'pdal::LasHeader'
>         pdal::ILeStream          input{ path_.native() };
>         input >> header;
>         return header;
>     }
>
> What would be the correct way to read the header information from my code?
> It would be nice to do it for any point cloud file, but I’m happy to
> settle for las/laz files.
>
> Best regards,
>
> Peder Axensten
> Systems Developer
>
> Remote Sensing
> Department of Forest Resource Management
> Swedish University of Agricultural Sciences
> SE-901 83 Umeå
> Visiting address: Skogsmarksgränd
> Phone: +46 90 786 85 00
> peder.axensten at slu.se, www.slu.se/srh
>
> The Department of Forest Resource Management is environmentally certified
> in accordance with ISO 14001.
>
> > On 23 Mar 2022, at 12:34, Andrew Bell <andrew.bell.ia at gmail.com> wrote:
> >
> > On Wed, Mar 23, 2022 at 5:14 AM Peder Axensten <Peder.Axensten at slu.se>
> wrote:
> > Dear list,
> >
> > Previously, I could obtain a pdal::LasHeader through:
> >
> > inline pdal::LasHeader get_header( const std::filesystem::path & path_ )
> {
> > pdal::LasHeader header;
> > pdal::ILeStream input{ path_.native() };
> > input >> header;
> > return header;
> > }
> >
> > But in the latest version of pdal the header copy constructor is
> implicitly deleted.
> >
> > This issue has already been reported and fixed and will be included in
> the final 2.4 release:
> >
> >  https://github.com/PDAL/PDAL/pull/3713
> >
> > The tool needs to process all las-files of a specified directory (and
> its sud-directories). If I need to read the contents of files that could
> actually be ignored, it would increase processing time probably tenfolds.
> Is there a way to avoid this?
> >     Maybe a previous stage in the pipeline to filter files based only on
> their header (bounding box) info?
> >     If I implement it as a streaming operation, could I get the bounding
> box from header info and possibly not stream anything?
> >
> > The bounding box of a LAS file is always stored at offsets 179-226, so
> you can read them directly if you like, but as I said above, I have
> re-enabled copying of LasHeader.
> >
> > --
> > Andrew Bell
> > andrew.bell.ia at gmail.com
>
> ---
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-- 
Andrew Bell
andrew.bell.ia at gmail.com
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