# 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 (or filename) items.

    [
        {
            "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",
                "filename": "path-to-my-file.input"
                }],
            "filename":"outputfile.las"
        }
    ]

Note

data or filename must be specified. Data must always be provided as base64 encoded strings, but content of filename is expected to be raw data.

## Example

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

## Options

filename

  Output filename. 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 0 and 65535 - 0 implies “unassigned”) [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> [, ...]`. Any valid PDAL type can be specified.

  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.

  PDAL writes an extra bytes VLR (User ID: LASF_Spec, Record ID: 4) when extra dims are written. The VLR describes the extra dimensions specified by this option. Note that reading of this VLR is only specified for LAS version 1.4, though some systems will honor it for earlier file formats. The LAS reader requires the option use_eb_vlr in order to read the extra bytes VLR for files written with 1.1 - 1.3 LAS format.

  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]

where

  An expression that limits points passed to a writer. Points that don’t pass the expression skip the stage but are available to subsequent stages in a pipeline. [Default: no filtering]

where_merge

  A strategy for merging points skipped by a ‘where’ option when running in standard mode. If `true`, the skipped points are added to the first point view returned by the skipped filter. If `false`, skipped points are placed in their own point view. If `auto`, skipped points are merged into the returned point view provided that only one point view is returned and it has the same point count as it did when the writer was run. [Default: `auto`]