[pdal] Modify the resolution

[thejus kambi]

Hello Howard,

I apologize for the stupid question.

How is the scale value dependent on the resolution of the coordinates.
Isn't the data type for coordinates double?
I see in the help file "written value = (nominal value - offset) / scale".
so does this mean the written value is changed from double to integer when
it is being written to file?
Also, Is it limited to PDAL or LAS files in general.

Warm Regards,
Thejus






On Thu, May 9, 2019 at 7:41 AM Howard Butler <howard at hobu.co> wrote:

>
>
> On May 9, 2019, at 7:25 AM, thejus kambi <thejus.kambi at gmail.com> wrote:
>
> Hello,
>
> Is there a way to modify the resolution of coordinates stored in the
> LAS/LAZ files. I find currently the file stores upto 2 decimal places. Is
> there a way to increase or decrease it?
>
>
> Thejus,
>
> You control these with the writers.las.scale_{x|y|z} options of
> writers.las https://pdal.io/stages/writers.las.html Additionally, if you
> are working exclusively with LAS data, you might also issue the
> --writers.las.forward=all option to carry forward all metadata, including
> scale/offset from a single file transformation.
>
> pdal translate in.las out.las --writers.las.scale_x=0.001
> --writers.las.scale_y=0.001 --writers.las.scale_z=0.001
> --writers.las.offset_x=auto --writers.las.offset_y=auto
> --writers.las.offset_z=auto
>
>
> pdal translate in.las out.las --writers.las.forward=all
>
>
> There are a couple of reasons why we do not default these options to
> always being set:
>
> * What are we to do if the translation includes multiple files at once?
> * Ambiguities that result from changing the LAS version
> * What are we to do in situations where multiple LAS files are being
> written?
>
> It is a surprise, but users have to be explicit about their LAS metadata
> settings with PDAL. Once they are, they should be able to achieve most
> everything they need.
>
> Additionally, I wrote a tutorial of these issues on the website at
> https://pdal.io/tutorial/las.html
>
> Hope this helps,
>
> Howard
>
>
>
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