.. _readers.copc:

readers.copc
============

The **COPC Reader** supports reading from `COPC format`_ files. A COPC file is
a `LASzip`_ (compressed LAS) file that organizes its data spatially, allowing for
incremental loading and spatial filtering.

.. _LASzip: http://laszip.org
.. _COPC format: https://copc.io/

.. note::

  LAS stores X, Y and Z dimensions as scaled integers.  Users converting an
  input LAS file to an output LAS file will frequently want to use the same
  scale factors and offsets in the output file as existed in the input
  file in order to
  maintain the precision of the data.  Use the `forward` option of
  :ref:`writers.las` to facilitate transfer of header information from
  source COPC files to destination LAS/LAZ files.

.. note::

  COPC files can contain datatypes that are actually arrays rather than
  individual dimensions.  Since PDAL doesn't support these datatypes, it
  must map them into datatypes it supports.  This is done by appending the
  array index to the name of the datatype.  For example, datatypes 11 - 20
  are two dimensional array types and if a field had the name Foo for
  datatype 11, PDAL would create the dimensions Foo0 and Foo1 to hold the
  values associated with LAS field Foo.  Similarly, datatypes 21 - 30 are
  three dimensional arrays and a field of type 21 with the name Bar would
  cause PDAL to create dimensions Bar0, Bar1 and Bar2.  See the information
  on the extra bytes VLR in the `LAS Specification`_ for more information
  on the extra bytes VLR and array datatypes.

.. _LAS Specification: http://www.asprs.org/wp-content/uploads/2019/07/LAS_1_4_r15.pdf

.. warning::

  COPC files that use the extra bytes VLR and datatype 0 will be accepted,
  but the data associated with a dimension of datatype 0 will be ignored
  (no PDAL dimension will be created).

.. embed::

.. streamable::


Example
-------

.. code-block:: json

  [
      {
          "type":"readers.copc",
          "filename":"inputfile.copc.laz"
      },
      {
          "type":"writers.text",
          "filename":"outputfile.txt"
      }
  ]

Options
-------

_`filename`
  COPC file to read. Remote file specifications (http, AWS, Google, Azure, Dropbox) are supported.
  [Required]

.. include:: reader_opts.rst

bounds
  The extent of the data to select in 2 or 3 dimensions, expressed as a string,
  e.g.: ``([xmin, xmax], [ymin, ymax], [zmin, zmax])``.  If omitted, the entire dataset
  will be selected. The bounds specification can be followed by a slash ('/') and a
  spatial reference specification to apply to the bounds specification.

polygon
  A clipping polygon, expressed in a well-known text string,
  e.g.: ``POLYGON((0 0, 5000 10000, 10000 0, 0 0))``.  This option can be
  specified more than once. Multiple polygons will will be treated
  as a single multipolygon. The polygon specification can be followed by a slash ('/') and a
  spatial reference specification to apply to the polygon.

ogr
  A JSON object representing an OGR query to fetch polygons to use for filtering. The polygons
  fetched from the query are treated exactly like those specified in the ``polygon`` option.
  The JSON object is specified as follows:

  .. code-block:: json

    {
        "drivers": "OGR drivers to use",
        "openoptions": "Options to pass to the OGR open function [optional]",
        "layer": "OGR layer from which to fetch polygons [optional]",
        "sql": "SQL query to use to filter the polygons in the layer [optional]",
        "options":
        {
            "geometry", "WKT or GeoJSON geomtry used to filter query [optional]"
        }
    }

requests
  The number of worker threads processing data. The optimal number depends on your system
  and your network connection, but more is not necessarily better.  A reasonably fast
  network connection can often fetch data faster than it can be processed, leading to
  memory consumption and slower performance. [Default: 15]

resolution
  Limit the pyramid levels of data to fetch based on the expected resolution of the data.
  Units match that of the data. [Default: no resolution limit]

header
  HTTP headers to forward for remote endpoints. Specify as a JSON
  object of key/value string pairs.

query
  HTTP query parameters to forward for remote endpoints. Specify as a JSON
  object of key/value string pairs.

vlr
  Read LAS VLRs and import as metadata. [Default: false]

keep_alive
  The number of chunks to keep active in memory while reading [Default: 10]

fix_dims
  Make invalid dimension names valid by converting disallowed characters to '_'. Only
  applies to names specified in an extra-bytes VLR. [Default: true]

srs_vlr_order
  Preference order to read SRS VLRs (list of 'wkt1', 'wkt2', or 'projjson').
  [Default: 'wkt1, wkt2, projjson']

nosrs
  Don't read the SRS VLRs. The data will not be assigned an SRS. This option is
  for use only in special cases where processing the SRS could cause performance
  issues. [Default: false]
