# writers.draco

Draco is a library for compressing and decompressing 3D geometric meshes and point clouds and was designed and built for compression efficiency and speed. The code supports compressing points, connectivity information, texture coordinates, color information, normals, and any other generic attributes associated with geometry.

This writer aims to use the encoding feature of the Draco library to compress and output Draco files.

## Example

This example will read in a las file and output a Draco encoded file, with options to include PDAL dimensions X, Y, and Z as double, and explicitly setting quantization levels of some of the Draco attributes.

[
  {

    “type”: “readers.las”, “filename”: “color.las”

  }, {

  > “type”: “writers.draco”, “filename”: “draco.drc”, “dimensions”: {

  > > “X”: “float”, “Y”: “float”, “Z”: “float”

  > }, “quantization”: {

  > > “NORMAL”: 8, “TEX_COORD”: 7, “GENERIC”: 6

  > }

  }

]

## Options

filename

  Output file name. [Required]

dimensions

  A json map of PDAL dimensions to desired data types. Data types must be string and must be available in PDAL’s Type specification. Any dimension that combine to make one Draco dimension must all have the same type (eg. POSITION is made up of X, Y, and Z. X cannot by float while Y and Z are specified as double)

  This argument will filter the dimensions being written to only the dimensions that have been specified. If that dimension is part of a multi-dimensional draco attribute (POSITION=[X,Y,Z]), then any dimension not specified will be filled in with zeros.

quantization

  A json map of Draco attributes to desired quantization levels. These levels must be integers. Default quantization levels are below, and will be overridden by any values placed in the options.

..code-block:: json {

> “POSITION”: 11, “NORMAL”: 7, “TEX_COORD”: 10, “COLOR”: 8, “GENERIC”: 8

}

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`]