# filters.ferry¶

The ferry filter is used to stash intermediate variables as part of processing data. For example, a common scenario is to keep both the original value and the reprojected X and Y variables in a scenario that uses the filters.reprojection filter. In the normal case, the X and Y data would be overwritten with the new longitude and latitude values as part of the reprojection. The ferry filter will allow you to keep this around for later use.

## Example¶

In this scenario, we are doing what is described above – stashing the pre-projection X and Y values into the StatePlaneX and StatePlaneY dimensions. Future processing, can then operate on these data.

{
"pipeline":[
"uncompressed.las",
{
"spatialreference":"EPSG:2993",
"filename":"../las/1.2-with-color.las"
},
{
"type":"filters.ferry",
"dimensions":"X = StatePlaneX, Y=StatePlaneY"
},
{
"type":"filters.reprojection",
"out_srs":"EPSG:4326+4326"
},
{
"type":"writers.las",
"scale_x":"0.0000001",
"scale_y":"0.0000001",
"filename":"colorized.las"
}
]
}


## Options¶

dimensions
A list of dimensions whose values should be copied to the specified dimensions. The format of the option is <from>=<to>, <from>=<to>,... Spaces are ignored. ‘from’ dimensions must exist and have been created by a reader or filter. ‘to’ dimensions will be created if necessary.