filters.python produces incorrect JSON metadata

[bacek]

Describe the bug
Running pdal pipeline with filters.python produces incorrect JSON metadata.

$ pdal -v 8 pipeline --metadata m2.json pl2.json 
(PDAL Debug) Debugging...
(pdal pipeline Debug) Attempting to load plugin '/usr/local/lib/libpdal_plugin_filter_python.so'.
(pdal pipeline Debug) Loaded plugin '/usr/local/lib/libpdal_plugin_filter_python.so'.
(pdal pipeline Debug) Initialized plugin '/usr/local/lib/libpdal_plugin_filter_python.so'.
(pdal pipeline Debug) Executing pipeline in standard mode.
(pdal pipeline filters.python Debug) 					filters.python source=[54 bytes], module=foo, function=foo
 processing 0 points.
Hello
(pdal pipeline writers.las Debug) Wrote 0 points to the LAS file

Dummy pipepline with 2 inputs.

[
  "empty.laz",
  "empty.laz",
  {
    "type": "filters.merge"
  },
  {
    "type": "filters.python",
    "script": "./foo.py",
    "function": "foo",
    "module": "foo"
  },
  "out.laz"
]

$ cat foo.py
def foo(ins,outs):
    print("Hello")
    return True

Validating:
stages->filters.python software_id and system_id are not quoted.

jq . < m2.json 
parse error: Invalid numeric literal at line 19, column 57

$ cat m2.json
cat m2.json 
{
  "stages":
  {
    "filters.merge":
    {
    },
    "filters.python":
    {
      "creation_doy": 143,
      "creation_year": 2021,
      "dataformat_id": 3,
      "filesource_id": 42493,
      "global_encoding": 0,
      "major_version": 1,
      "minor_version": 2,
      "offset_x": 0,
      "offset_y": 0,
      "offset_z": 0,
      "project_id": 00000000-0000-0000-0000-000000000000,
      "readers.las":
      [
        {
        },
        {
        }
      ],
      "root":
      {
      },
      "scale_x": 0.01,
      "scale_y": 0.01,
      "scale_z": 0.01,
      "software_id": PDAL 2.1.0 (810b3c),
      "srs":
      [
        {
        },
        {
        }
      ],
      "system_id": PDAL,
      "units":
      [
        {
        },
        {
        }
      ],
      "vlr_0":
      [
        {
        },
        {
        }
      ]
    },
    "readers.las":
    [
      {
        "comp_spatialreference": "",
        "compressed": true,
        "count": 0,
        "creation_doy": 143,
        "creation_doy":         {
          "temp": 143
        },
        "creation_year": 2021,
        "creation_year":         {
          "temp": 2021
        },
        "dataformat_id": 3,
        "dataformat_id":         {
          "temp": 3
        },
        "dataoffset": 333,
        "filesource_id": 42493,
        "filesource_id":         {
          "temp": 42493
        },
        "global_encoding": 0,
        "global_encoding":         {
          "temp": 0
        },
        "global_encoding_base64": "AAA=",
        "gtiff": "",
        "header_size": 227,
        "major_version": 1,
        "major_version":         {
          "temp": 1
        },
        "maxx": -1.797693135e+308,
        "maxy": -1.797693135e+308,
        "maxz": -1.797693135e+308,
        "minor_version": 2,
        "minor_version":         {
          "temp": 2
        },
        "minx": 1.797693135e+308,
        "miny": 1.797693135e+308,
        "minz": 1.797693135e+308,
        "offset_x": 0,
        "offset_x":         {
          "temp": 0
        },
        "offset_y": 0,
        "offset_y":         {
          "temp": 0
        },
        "offset_z": 0,
        "offset_z":         {
          "temp": 0
        },
        "point_length": 34,
        "project_id": "00000000-0000-0000-0000-000000000000",
        "project_id":         {
          "temp": "00000000-0000-0000-0000-000000000000"
        },
        "scale_x": 0.01,
        "scale_x":         {
          "temp": 0.01
        },
        "scale_y": 0.01,
        "scale_y":         {
          "temp": 0.01
        },
        "scale_z": 0.01,
        "scale_z":         {
          "temp": 0.01
        },
        "software_id": "PDAL 2.1.0 (810b3c)",
        "software_id":         {
          "temp": "PDAL 2.1.0 (810b3c)"
        },
        "spatialreference": "",
        "srs":
        {
          "compoundwkt": "",
          "horizontal": "",
          "isgeocentric": false,
          "isgeographic": false,
          "prettycompoundwkt": "",
          "prettywkt": "",
          "proj4": "",
          "units":
          {
            "horizontal": "unknown",
            "vertical": ""
          },
          "vertical": "",
          "wkt": ""
        },
        "system_id": "PDAL",
        "system_id":         {
          "temp": "PDAL"
        },
        "vlr_0":
        {
          "data": "AgAAAAMEAwAAAAAAUMMAAP////////////////////8DAAYAFAACAAcACAACAAgABgACAA==",
          "description": "http://laszip.org",
          "record_id": 22204,
          "user_id": "laszip encoded"
        }
      },
      {
        "comp_spatialreference": "",
        "compressed": true,
        "count": 0,
        "creation_doy": 143,
        "creation_year": 2021,
        "dataformat_id": 3,
        "dataoffset": 333,
        "filesource_id": 42493,
        "global_encoding": 0,
        "global_encoding_base64": "AAA=",
        "gtiff": "",
        "header_size": 227,
        "major_version": 1,
        "maxx": -1.797693135e+308,
        "maxy": -1.797693135e+308,
        "maxz": -1.797693135e+308,
        "minor_version": 2,
        "minx": 1.797693135e+308,
        "miny": 1.797693135e+308,
        "minz": 1.797693135e+308,
        "offset_x": 0,
        "offset_y": 0,
        "offset_z": 0,
        "point_length": 34,
        "project_id": "00000000-0000-0000-0000-000000000000",
        "scale_x": 0.01,
        "scale_y": 0.01,
        "scale_z": 0.01,
        "software_id": "PDAL 2.1.0 (810b3c)",
        "spatialreference": "",
        "srs":
        {
          "compoundwkt": "",
          "horizontal": "",
          "isgeocentric": false,
          "isgeographic": false,
          "prettycompoundwkt": "",
          "prettywkt": "",
          "proj4": "",
          "units":
          {
            "horizontal": "unknown",
            "vertical": ""
          },
          "vertical": "",
          "wkt": ""
        },
        "system_id": "PDAL",
        "vlr_0":
        {
          "data": "AgAAAAMEAwAAAAAAUMMAAP////////////////////8DAAYAFAACAAcACAACAAgABgACAA==",
          "description": "http://laszip.org",
          "record_id": 22204,
          "user_id": "laszip encoded"
        }
      }
    ],
    "writers.las":
    {
      "count": 0,
      "filename":
      [
        "out.laz"
      ],
      "maxx": -1.797693135e+308,
      "maxy": -1.797693135e+308,
      "maxz": -1.797693135e+308,
      "minx": 1.797693135e+308,
      "miny": 1.797693135e+308,
      "minz": 1.797693135e+308
    }
  }
}

Expected behavior
Generated JSON is valid.

System/installation information:
Please provide information on your PDAL version (pdal --version) and system (e.g., uname -a or ver).

$ uname -a
Linux sunburst 5.18.0-0.deb11.4-amd64 #1 SMP PREEMPT_DYNAMIC Debian 5.18.16-1~bpo11+1 (2022-08-12) x86_64 GNU/Linux

$ pdal --version
pdal 2.3.0 (git-version: <plp l)

[hobu]

This does not happen for me with 2.4-maintenance or the master branch of PDAL. I wasn't using an empty.laz, however. Is that a key part of this?

Also, the JSON sure looks funky even if it is valid 😦

[bacek]

You need "empty.laz" (or any other las file with software_id) to get broken JSON.