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

[Rose Phillips]

LAZ files with 129 bits are downloadable for free here :-

aws s3 cp s3://pc-bulk/NZ20_Westport/ . --recursive --endpoint-url https://opentopography.s3.sdsc.edu --no-sign-request

Using the same pipeline as below I was having the same issue with example file from the above bucket CL2_BR20_2020_1000_4134.laz – output file still contained the 129 bit when explicitly filtered out by writers.las.where statement.

From: Andrew Bell <andrew.bell.ia at gmail.com<mailto:andrew.bell.ia at gmail.com>>
Sent: Wednesday, 4 August 2021 11:57 a.m.
To: Rose Phillips <RPhillips at linz.govt.nz<mailto:RPhillips at linz.govt.nz>>
Cc: pdal at lists.osgeo.org<mailto:pdal at lists.osgeo.org>
Subject: Re: [pdal] Attempting to filter out (1) Unclassified points flagged as Withheld

The pipeline doesn't seem to match the output you show, so it's hard to know what's going on. If you want to share a file I can see what's up.

On Tue, Aug 3, 2021 at 5:22 PM Rose Phillips <RPhillips at linz.govt.nz<mailto:RPhillips at linz.govt.nz>> wrote:
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<mailto:andrew.bell.ia at gmail.com>>
Sent: Tuesday, 3 August 2021 11:00 p.m.
To: Rose Phillips <RPhillips at linz.govt.nz<mailto:RPhillips at linz.govt.nz>>
Cc: pdal at lists.osgeo.org<mailto: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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--
Andrew Bell
andrew.bell.ia at gmail.com<mailto:andrew.bell.ia at gmail.com>
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