PointOnAreaOverlayer

The Group By parameter specifies a series of attributes that must match on the point and polygon features before the attributes will be merged. This can be used to ensure that the overlay occurs only on certain groups of features.

Note: How parallel processing works with FME: see About Parallel Processing for detailed information.

This parameter determines whether or not the transformer should perform the work across parallel processes. If it is enabled, a process will be launched for each group specified by the Group By parameter.

Parallel Processing Levels

For example, on a quad-core machine, minimal parallelism will result in two simultaneous FME processes. Extreme parallelism on an 8-core machine would result in 16 simultaneous processes.

You can experiment with this feature and view the information in the Windows Task Manager and the Workbench Log window.

Yes: This transformer will process input groups in order. Changes on the value of the Group By parameter on the input stream will trigger batch processing on the currently accumulating group. This will improve overall speed if groups are large/complex, but could cause undesired behavior if input groups are not truly ordered.

No: This is the default behavior. Processing will only occur in this transformer once all input is present.

The Overlap Count Attribute added to output area features holds the number of point features that they contained.

If Areas First is set to Yes, then the PointOnAreaOverlayer assumes that all Area features will enter the transformer before any Point features. This can reduce memory use of the PointOnAreaOverlayer if you have many Point features to overlay. Any further Area features that arrive after the first Point feature will be logged with a warning and discarded.

Merge Incoming: The original feature will retain all of its own un-conflicted attributes, and will additionally acquire any un-conflicted attributes that the incoming feature has. This mode will handle conflicted attributes based on the Conflict Resolution parameter.

Prefix Incoming: The original feature will retain all of its own attributes. In addition, the original will acquire attributes reflecting the incoming feature’s attributes, with the name prefixed with the Prefix parameter.

Only Use Incoming: The original feature will have all of its attributes removed, except geometry attributes that start with fme_. Then, all of the attributes from one (arbitrary) incoming feature will be placed onto the original.

Use Original: If a conflict occurs, the original values will be maintained.

Use Incoming: If a conflict occurs, the values of the incoming will be transferred onto the original.

If the Accumulation Mode parameter is set to Prefix Incoming, this value will prefix attributes that are being added to the original feature from the incoming feature.

If the optional List Name is supplied, the attributes of each area containing an output point are added to that point's list, and the attributes of each point contained by an output area are added to that area's list.

Note: Attribute lists are not accessible from the output schema in Workbench unless they are first processed using a transformer that operates on them, such as ListExploder or ListConcatenator. All attribute list transformers are displayed in the Contents pane of the Transformer Help under Lists. Alternatively, AttributeExposer can be used.