Solves proximity conflicts between features using a variant of the Nickerson displacement algorithm. This transformer is usually used after generalization.
Input and Output Ports
The features routed into the transformer through the Base port are geometrically frozen (cannot move).
The features routed in through the Candidate port are compared against the Base feature(s), displaced as necessary, and exit through the Displaced port. If no displacement occurred, they exit through the Untouched port.
Each comparison/displacement is independent of the others.
Base features with geometries other than point, curve or area (polygon or ellipse or donut) will exit through the InvalidBase port. Candidate features with geometries other than point, curve or simple area (polygon or ellipse) will exit through the InvalidCandidate port.
The ExtraBase port holds extra Base features as described in the Base Type parameter below.
Parameters
Transformer
Group By
You can use this option to narrow down which candidate features to compare with which base features.
Group By Mode
Process At End (Blocking): This is the default behavior. Processing will only occur in this transformer once all input is present.
Process When Group Changes (Advanced): This transformer will process input groups in order. Changes of the value of the Group By parameter on the input stream will trigger processing on the currently accumulating group. This may improve overall speed (particularly with multiple, equally-sized groups), but could cause undesired behavior if input groups are not truly ordered.
Considerations for Using Group By
There are two typical reasons for using Process When Group Changes (Advanced) . The first is incoming data that is intended to be processed in groups (and is already so ordered). In this case, the structure dictates Group By usage - not performance considerations.
The second possible reason is potential performance gains.
Performance gains are most likely when the data is already sorted (or read using a SQL ORDER BY statement) since less work is required of FME. If the data needs ordering, it can be sorted in the workspace (though the added processing overhead may negate any gains).
Sorting becomes more difficult according to the number of data streams. Multiple streams of data could be almost impossible to sort into the correct order, since all features matching a Group By value need to arrive before any features (of any feature type or dataset) belonging to the next group. In this case, using Group By with Process At End (Blocking) may be the equivalent and simpler approach.
Note: Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.
As with many scenarios, testing different approaches in your workspace with your data is the only definitive way to identify performance gains.
Parameters
Stiffness
Specifies how much the displacement at one point in the candidate feature's geometry should affect the neighboring points. A lower value means that the candidate geometry can be deformed easily, while a higher value means that it will try its best to keep its original shape.
Minimum Separating Distance
The Minimum Separating Distance parameter specifies the minimum separating distance between the candidate feature's geometry and the base feature's geometry after displacement.
Displace Endpoints
The Displace Endpoints parameter specifies whether or not to displace the endpoints of candidate features whose geometries are unclosed lines.
Base Type
The Base Type parameter specifies whether only a single Base feature will be used, or whether all Base features will be used. If Bases First is selected, then the transformer assumes that all Base features will enter the transformer before any Candidate features. Any further Base features that arrive after the first Candidate will be output through the ExtraBase port. The same goes for any Base features after the first when in Single Base mode.
Editing Transformer Parameters
Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click 
beside the applicable parameter. For more information, see Transformer Parameter Menu Options.
Transformer Categories
Related Transformers
FME Licensing Level
FME Professional edition and above
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Keywords: displacement resolve conflict generalization Nickerson generalize NickersonDisplacer