MRF3DCleaner

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

Features can also be output through the Flagged port if any of the Remove Dangles, Remove Short Geometries and Compute True Intersections is set to Flag. Each of these features has a new attribute mrf_clean_flag added to specify whether this feature is flagged as being shorter than the cleaning tolerance value ("short"), a dangling geometry ("dangle") or an intersection point ("intersection").

The default behavior is to use the entire set of input features as the group. This option allows you to select attributes that define which groups to form—each set of features that have the same value for all of these attributes will be processed as an independent group.

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.

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

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

If set to Yes, intersections between all input features are computed, breaking arcs and lines wherever an intersection occurs.

If set to Flag, the intersection point will be output through the Flagged port, with an mrf_clean_flag attribute set to "intersection".

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

If set to Yes, arcs and lines that are within the specified cleaning tolerance are extended – while maintaining line-work direction. No intersections are created while doing this. This option does not process overshoots; a combination of Compute Intersections and Remove Short Geometries can serve this purpose.

If set to Yes, a number of vertices of lines are removed. The number of vertices removed is controlled by a weeding tolerance of the value of (Filter Factor * value of Cleaning Tolerance) or (Filter Factor * value of Feature Tolerance Attribute). The latter is always used when it is valid and the Feature Tolerance Attribute is specified. The larger the value of weeding tolerance, the more vertices will be removed.

If set to Yes, then features that have at least one free end point and have lengths smaller than (Dangle Factor * value of Cleaning Tolerance) or (Dangle Factor * value of Feature Tolerance Attribute) are removed.

If set to Remove Short and Flag Long, then features that have at least one free end point will either be removed as above, or its end point will be output through the Flagged port, with an mrf_clean_flag attribute set to "dangle".

The default value of Dangle Factor is 1.0 and the minimum is 0.0.

This parameter is used with Remove Dangles to determine if a dangling feature is too short.

The default value is 1.0 and the minimum value is 0.0.

This parameter is used with Generalize Lines to determine a weeding tolerance.

The default value is 1.0 and the minimum value is 0.0.

If set to Yes, features that have lengths smaller than the specified cleaning tolerances are deleted.

If set to Flag, a point on the feature will be output through the Flagged port, with an mrf_clean_flag attribute set to "short".

If set to Yes, duplicated features are deleted. Features are considered to be duplicates if their geometries are within the cleaning tolerance and only features with a smaller cleaning tolerance will remain after cleaning.

If set to Yes, then singly-connected features are joined to form longer ones. A pair of linear features becomes a candidate for joining only when the two are singly connected at a given node or end point.

If set to Yes, then the geometry of a feature can be changed to match that of another, if the two are approximately the same to begin with.

If set to Yes, then area features such as polygons or donuts will be cleaned without stroking them first.