# filters.streamcallback

The Stream Callback Filter provides a simple hook for a user-specified action to occur for each point. The stream callback filter is for use by C++ programmers extending PDAL functionality and isn’t useful to end users.

Default Embedded Stage

This stage is enabled by default

Streamable Stage

This stage supports streaming operations

## 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`]