# writers.las

The LAS Writer supports writing to LAS format files, the standard interchange file format for LIDAR data.

Warning

Scale/offset are not preserved from an input LAS file. See below for information on the scale/offset options and the `forward` option.

Default Embedded Stage

This stage is enabled by default

Streamable Stage

This stage supports streaming operations

## VLRs

VLRs can be created by providing a JSON node called vlrs with objects containing user_id and data items.

    {
      "pipeline":[
        {
          "type":"readers.las",
          "filename":"inputfile.las"
        },
        {
          "type":"writers.las",
          "vlrs": [{
                    "description": "A description under 32 bytes",
                    "record_id": 42,
                    "user_id": "hobu",
                    "data": "dGhpcyBpcyBzb21lIHRleHQ="
                   },
                   {
                    "description": "A description under 32 bytes",
                    "record_id": 43,
                    "user_id": "hobu",
                    "data": "dGhpcyBpcyBzb21lIG1vcmUgdGV4dA=="
                    }
                  ],
          "filename":"outputfile.las"
        }
      ]
    }

## Example

    {
      "pipeline":[
        {
          "type":"readers.las",
          "filename":"inputfile.las"
        },
        {
          "type":"writers.las",
          "filename":"outputfile.las"
        }
      ]
    }

## Options

filename
  LAS file to read. The writer will accept a filename containing a single placeholder character (#). If input to the writer consists of multiple PointViews, each will be written to a separate file, where the placeholder will be replaced with an incrementing integer. If no placeholder is found, all PointViews provided to the writer are aggregated into a single file for output. Multiple PointViews are usually the result of using filters.splitter, filters.chipper or filters.divider. [Required]
forward

  List of header fields whose values should be preserved from a source LAS file. The option can be specified multiple times, which has the same effect as listing values separated by a comma. The following values are valid: `major_version`, `minor_version`, `dataformat_id`, `filesource_id`, `global_encoding`, `project_id`, `system_id`, `software_id`, `creation_doy`, `creation_year`, `scale_x`, `scale_y`, `scale_z`, `offset_x`, `offset_y`, `offset_z`. In addition, the special value `header` can be specified, which is equivalent to specifying all the values EXCEPT the scale and offset values. Scale and offset values can be forwarded as a group by using the special values `scale` and `offset` respectively. The special value `all` is equivalent to specifying `header`, `scale`, `offset` and `vlr` (see below). If a header option is specified explicitly, it will override any forwarded header value. If a LAS file is the result of multiple LAS input files, the header values to be forwarded must match or they will be ignored and a default will be used instead.

  VLRs can be forwarded by using the special value `vlr`. VLRs containing the following User IDs are NOT forwarded: `LASF_Projection`, `liblas`, `laszip encoded`. VLRs with the User ID `LASF_Spec` and a record ID other than 0 or 3 are also not forwarded. These VLRs are known to contain information regarding the formatting of the data and will be rebuilt properly in the output file as necessary. Unlike header values, VLRs from multiple input files are accumulated and each is written to the output file. Forwarded VLRs may contain duplicate User ID/Record ID pairs.

minor_version
  All LAS files are version 1, but the minor version (0 - 4) can be specified with this option. [Default: 2]
software_id
  String identifying the software that created this LAS file. [Default: PDAL version num (build num)]”
creation_doy
  Number of the day of the year (January 1 == 0, Dec 31 == 365) this file is being created.
creation_year
  Year (Gregorian) this file is being created.
dataformat_id

  Controls whether information about color and time are stored with the point information in the LAS file. [Default: 3]

  - 0 == no color or time stored
  - 1 == time is stored
  - 2 == color is stored
  - 3 == color and time are stored
  - 4 [Not Currently Supported]
  - 5 [Not Currently Supported]
  - 6 == time is stored (version 1.4+ only)
  - 7 == time and color are stored (version 1.4+ only)
  - 8 == time, color and near infrared are stored (version 1.4+ only)
  - 9 [Not Currently Supported]
  - 10 [Not Currently Supported]
system_id
  String identifying the system that created this LAS file. [Default: “PDAL”]
a_srs
  The spatial reference system of the file to be written. Can be an EPSG string (e.g. “EPSG:26910”) or a WKT string. [Default: Not set]
global_encoding
  Various indicators to describe the data. See the LAS documentation. Note that PDAL will always set bit four when creating LAS version 1.4 output. [Default: 0]
project_id
  UID reserved for the user [Default: Nil UID]
compression
  Set to “lazperf” or “laszip” to apply compression to the output, creating a LAZ file instead of an LAS file. “lazperf” selects the LazPerf compressor and “laszip” (or “true”) selects the LasZip compressor. PDAL must have been built with support for the requested compressor. [Default: “none”]
scale_x, scale_y, scale_z

  Scale to be divided from the X, Y and Z nominal values, respectively, after the offset has been applied. The special value `auto` can be specified, which causes the writer to select a scale to set the stored values of the dimensions to range from [0, 2147483647]. [Default: .01]

  Note: written value = (nominal value - offset) / scale.

offset_x, offset_y, offset_z

  Offset to be subtracted from the X, Y and Z nominal values, respectively, before the value is scaled. The special value `auto` can be specified, which causes the writer to set the offset to the minimum value of the dimension. [Default: 0]

  Note: written value = (nominal value - offset) / scale.

filesource_id
  The file source id number to use for this file (a value between 1 and 65535) [Default: 0]
discard_high_return_numbers
  If true, discard all points with a return number greater than the maximum supported by the point format (5 for formats 0-5, 15 for formats 6-10). [Default: false]
extra_dims

  Extra dimensions to be written as part of each point beyond those specified by the LAS point format. The format of the option is <dimension_name>=<type>, … where type is one of: int8, int16, int32, int64, uint8, uint16, uint32, uint64, float, double `_t` may be added to any of the type names as well (e.g., uint32_t). When the version of the output file is specified as 1.4 or greater, an extra bytes VLR (User ID: LASF_Spec, Record ID: 4), is created that describes the extra dimensions specified by this option.

  The special value `all` can be used in place of a dimension/type list to request that all dimensions that can’t be stored in the predefined LAS point record get added as extra data at the end of each point record.

  Setting –verbose=Info will provide output on the names, types and order of dimensions being written as part of the LAS extra bytes.

pdal_metadata
  Write two VLRs containing JSON output with both the Metadata and Pipeline serialization. [Default: false]