TopologyBuilder

The transformer accepts node, line, and area features. Aggregate and Multi features are invalid and will be rejected, unless Deaggregate Input is set to Yes.

Topologically significant nodes (point geometries) are output through this port.

Topologically significant edges (curve geometries) are output via this port.

Topologically significant faces (area geometries) are output through this port.

The output area, by subtraction, represents everything not covered by the faces.

Features without point, text, curve, or area geometries are output through this port along with an additional attribute, fme_rejection_code, to indicate the reason for rejection.

The input features may be grouped into separate topology sets based on attribute values. All attributes are carried across from the input features to the output 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.

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

By Group: 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.

The number indicates the maximum length to output any edge. If any line contains more than this number of coordinates, it will be broken into pieces which are output separately, each with their own edge IDs, and correctly noded. A value of 0 indicates an unlimited number of coordinates per edge.

If set to Yes, the transformer enters a mode where no collinear edges or overlapping nodes are output at all, whether they came from source linear features or from the borders of source area features or input points, or calculated as intersection points. In this mode, all output edges or nodes which were overlapping with at least one direct input will contain a list attribute (_overlapping_input_data) with information about each input with which it was overlapping. This keyword sets the fieldname of the list attribute to contain all the attributes (except geometry attributes that start with fme_) from all of the input lines or points that were overlapping with the final output edge or node.

A side effect of this option is that only edges that form part of a face boundary will be considered in the calculation of _left_edge and _right_edge. (All edges originating only from line input will have their own ID supplied as their left edge ID, and the negation of this as their right edge ID.)

When this parameter is set to All, the transformer does the following:

• All of the edges from the output face will be listed in the comma-separated _edges attribute. A 0 entry separates edges of different boundaries. An example _edges attribute is "1,2,-3,0,5,0,7".
• If the universe consists of multiple disjoint areas, it will be returned as a single feature with a MultiArea geometry.

When this parameter is set to First Per Boundary, the transformer does the following:

• The first edge of each boundary will be in the _edges list attribute. An example list is _edges{0} = 1, _edges{1} = 5, _edges{2} = 7.
• The value will always be positive, regardless of the direction of the edge.
• If the universe consists of multiple disjoint areas, a different feature will be returned for each area.

When this parameter is set to First Per Outer and Disjoint Inner Boundary, the transformer does the following:

• The first edge of each outer and disjoint inner boundary will be in the _edges list attribute. If an inner boundary is topologically connected to the outer boundary, it is not considered disjoint. If two inner boundaries are topologically connected to each other, only one is considered disjoint. An example list is _edges{0} = 1, _edges{1} = 5.
• The value will always be positive, regardless of the direction of the edge.
• If the universe consists of multiple disjoint areas, a different feature will be returned for each area.

If Propagate All Attributes From Input is set to Yes, attribute lists are added to each output feature, composed of attributes from the relevant input features. For each node, this will be a list of edges and a list of faces touching the node; for edges, there will be a list of nodes and a list of faces; and for faces, a list of nodes and a list of edges.

For nodes:

• Edge attributes will be stored in the _node_angle{} list. This list is ordered counterclockwise.
• Face attributes will be stored in the _faces{} list. This list is not ordered.

For edges:

• Node attributes will be stored in the _nodes{} list. The start node’s attributes will be the first entry in the list. If the end node is different from the start node, the end node’s attributes will be the second entry in the list.
• Face attributes will be stored in the _faces{} list. This list is not ordered.

For faces:

• Node attributes will be stored in the _nodes{} list. This list is not ordered.
• Edge attributes will be stored in the _edges{} list. The edges in this list are in the same order that the edges are used to make the boundary of the face.

If set to Yes, input features will be deaggregated by flattening all levels of aggregate and multi geometries. Composite geometries will not be split and geometry instances will not be exploded. If set to No, input features will not be deaggregated and will be accepted or rejected based on their root level geometry.

Preserve Internal Edges (Advanced) specifies that coordinate "cycles" within a face are allowable and will be preserved. A "cycle" is an edge that occurs twice in the same face's boundary (once in each direction); the edge's ID will appear twice in that face's edge list, positive in one instance and negative in the other.

Assume Clean Data (Advanced) specifies that the input is topologically clean and noded properly and therefore no new nodes will be added to any geometries. To be topologically clean, the data must contain no un-noded self intersections; this may be confirmed using the appropriate Self Intersection rule inside GeometryValidator. Similarly, all intersections between geometries that should be acknowledged must have a coordinate at the location where they intersect. If Assume Clean Data is false, new points will be added to the geometries where intersections occur, if necessary, prior to constructing the topology.