# filters.skewnessbalancing

Skewness Balancing classifies ground points based on the approach outlined in [Bartels2010].

Default Embedded Stage

This stage is enabled by default

Note

For Skewness Balancing to work well, the scene being processed needs to be quite flat, otherwise many above ground features will begin to be included in the ground surface.

## Example

The sample pipeline below uses the Skewness Balancing filter to segment ground and non-ground returns, using default options, and writing only the ground returns to the output file.

    [
        "input.las",
        {
            "type":"filters.skewnessbalancing"
        },
        {
            "type":"filters.range",
            "limits":"Classification[2:2]"
        },
        "output.laz"
    ]

## Options

where

  An expression that limits points passed to a filter. 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 filter was run. [Default: `auto`]

Note

The Skewness Balancing method is touted as being threshold-free. We may still in the future add convenience parameters that are common to other ground segmentation filters, such as `returns` or `ignore` to limit the points under consideration for filtering.