[pdal] Modify the resolution

[Howard Butler]

> 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 <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 <https://pdal.io/tutorial/las.html>

Hope this helps,

Howard


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