MRF2DIntersector

Each feature that is output through the Cleaned port will have a new attribute "mrf_clean_status" added to specify whether the feature was modified, created, or unchanged in the cleaning process. The possible values of this attribute are "Modified", "Created" and "Original".

If Intersection Action is set to Split Lines at Intersections, the input lines will be split at true intersection points into separate output lines. If it is set to Flag Intersections, then true intersection points will be output through the Flagged port as points, labels, or circles, depending on the Flag Type selected.

If selected, each group of features with the same values in the Group By attributes will be processed separately from other groups.

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.

Cleaning tolerance is used as the default tolerance unless the Feature Tolerance Attribute is specified and valid. The minimum tolerance allowed is 0.0.

The number of layers used in cleaning the data is determined by the number of different tolerance values of input features. Features that have the same tolerances are processed as being on the same layer.

If set to Split Lines at Intersections, intersections are computed between all input features, breaking arcs and lines wherever an intersection occurs. If set to Flag Intersections, the Flag Type and Flag Size parameters are enabled.

If set to Yes, a fuzzy intersection is also created from geometries which are within one of the tolerance distances, but do not actually touch or cross.

This parameter sets the flag type for true intersection points as a point, label or circle, if Intersection Action is set to Flag Intersections.