# writers.greyhound¶

The Greyhound writer allows you to append new dimensions (or update existing appended dimensions) onto a Greyhound resource. This writer is unique among PDAL writers due to its strict limitation that it may only be used along with a Greyhound reader. Written points must also match the points that were read in a 1:1 manner (although there is no restriction against reordering), so intermediate filters that cull points are not allowed.

## Example¶

This example runs the SMRF ground-classification algorithm to populate the Classification dimension, the ferry filter to copy this dimension to a new dimension named Smrf, and then adds this dimension to the Greyhound resource.

{
"pipeline": [
{
"url": "data.greyhound.io/resource/autzen"
},
{
"type": "filters.smrf"
},
{
"type": "filters.ferry",
"dimensions": "Classification=Smrf"
},
{
"type": "writers.greyhound",
"name": "MySmrfDimensionSet",
"dims": ["Smrf"]
}
]
}


## Options¶

Many options that affect the behavior of the Greyhound writer are specified as parameters to the Greyhound reader - which are forwarded to the Greyhound writer.

name A string value for the name of this dimension set. This setting is used internally by the Greyhound server to group clusters of simultaneously appended dimensions. For example, a group of multiple classifications with different filter settings like [“SmrfCellSize_1.0”, “SmrfCellSize_1.5”] might be grouped as “SmrfComparison”.

dims A JSON array of string names of the dimensions to be written to the Greyhound resource.