[pdal] Attempting to filter out (1) Unclassified points flagged as Withheld

[Rose Phillips]

Hi Andrew,

Thank you for the heads up, I tried the following pipeline;

{
    "pipeline" : [
    {
        "type" : "readers.las",
        "filename" : "input.las"
    },
    {
        "type" : "writers.las",
        "a_srs" : "EPSG:2193+7839",
        "filesource_id" : "0",
        "filename" : "output.las",
        "where": "ClassFlags!=129"
    }
    ]
}

However my output LAZ file still had these bits intact;

{
  "file_size": 3007189,
  "filename": "C:\\Temp\\scan_angle\\test_file\\processed\\CL2_BW24_2020_1000_4526.laz",
  "now": "2021-08-04T09:20:17+1200",
  "pdal_version": "2.3.0 (git-version: Release)",
  "reader": "readers.las",
  "stats":
  {
    "statistic":
    [
      {
        "average": 6.704382019,
        "count": 1307434,
        "maximum": 129,
        "minimum": 2,
        "name": "Classification",
        "position": 0,
        "stddev": 21.69585237,
        "values":
        [
          2,
          3,
          4,
          5,
          7,
          9,
          18,
          129
        ],
        "variance": 470.7100099
      }
    ]
  }
}

Kindest regards Rose
______________________________________________________________________________________________________________________________________________________________
From: Andrew Bell <andrew.bell.ia at gmail.com>
Sent: Tuesday, 3 August 2021 11:00 p.m.
To: Rose Phillips <RPhillips at linz.govt.nz>
Cc: pdal at lists.osgeo.org
Subject: Re: [pdal] Attempting to filter out (1) Unclassified points flagged as Withheld



On Mon, Aug 2, 2021 at 5:39 PM Rose Phillips <RPhillips at linz.govt.nz<mailto:RPhillips at linz.govt.nz>> wrote:
Hi pdal’ers

These are my attempts to filter out (1) Unclassified Points flagged as withheld in LAS filers for further analyses.
Any chance you guys can point to where I have gone wrong?

pipelines I have tried using pdal 2.3.0: to filter out (1) unclassified points flagged as withheld;

1.

{
    "pipeline" : [
    {
        "type" : "readers.las",
        "filename" : "input.las"
    },
                {
                                "type":"filters.range",
                                "limits":"Classification![129:129]"
                },
    {
        "type" : "writers.las",
        "a_srs" : "EPSG:2193+7839",
        "filesource_id" : "0",
        "filename" : "output.las"
    }
    ]
  }

I think that this should filter out unclassified withheld points with LAS 1.2 and 1.3. With LAS 1.4, the withheld attribute is stored in the "ClassFlags" dimension, so you'll need to use boolean logic with that dimension and the "Classification" dimension to do what you want. You might also use pdal info --enumerate to make sure that your data has the values you think it does.

--
Andrew Bell
andrew.bell.ia at gmail.com<mailto:andrew.bell.ia at gmail.com>

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