Extends arcs and lines that are within the specified tolerance to correct undershoots while maintaining line-work direction. No intersections are created while doing this.
This does not process overshoots: the MRF2DCleaner with a combination of Compute Intersections and Delete Short Geometries can serve this purpose.
Output Ports
Cleaned
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".
Parameters
Transformer
Group By
If selected, each group of features with the same values in the Group By attributes will be processed separately from other groups.
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
Cleaning Tolerance
Cleaning tolerance is used as the default tolerance unless the Feature Tolerance Attribute is specified and valid. The minimum tolerance allowed is 0.0.
Feature Tolerance Attribute
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.
Usage Notes
This transformer performs the same operation as the MRF2DCleaner with the Correct Undershoots set to Yes and no other options selected. See the MRF2DCleaner for more details.1Portions of this work are the intellectual property of the MRF Geosystems Corporation and are used under license. Copyright © 2006 MRF Geosystems Corporation. All rights reserved.
FME Licensing Level
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