PathBuilder

Connects sequential line and/or arc features to create path geometry, preserving input segments.

Typical Uses

Combining geometry when input features are arcs
Combining geometry while preserving the input segments

How does it work?

The PathBuilder receives features with line or arc geometry and connects them in the order received.

Gaps between input features are connected as follows:

Line to line or arc: the first line is extended to to start point of the next feature.
Arc to line: the line is extended from its start point to the end point of the arc.
Arc to arc: a two-point line connects the end of the first arc to the start of the second arc.

Z coordinates are supported. Features with matching x and y coordinates but differing z values at their connection points are handled according to the Connect Z Mode parameter.

Attributes may be collected as a list attribute, preserving attribute values for every segment which can later be reconstructed as individual geometries with a PathSplitter.

Note that path geometry is not supported in all output formats. See also: Line , Arc, and Path geometry.

Examples

Example: Paths and List Attributes

If the individual segments of a longer line have varying attributes - fluctuating speed limits on a highway, for example - those attribute values can be preserved as a list attribute on path geometry and later retrieved when the path is split back into its component segments.

Creating a path and preserving attributes

In this example, we have a set of short lines that make up a bike path. The attribute values can vary from segment to segment.

We want to treat the bike path as a single piece of geometry, but retain the original segment details - both geometry and attribution.

The lines are routed into a PathBuilder.

In the parameters dialog, Generate List is enabled, the list is named SegmentAttributes, and All Attributes are added to list.

The output path has a SegmentAttributes list with 11 list items, and its geometry is a Path with 11 segments.

Note the difference between the attribute values on list items 9 and 10.

Splitting a path and recovering attributes

In this example, we want to recover the original geometry and attribution from the path with a list attribute created in the example above.

Note the path geometry with 11 segments and the SegmentAttributes list with 11 items.

The path is routed into a PathSplitter.

In the parameters dialog, Segment List is set to the list attribute SegmentAttributes.

The output features receive attribute values according to path segment and list item pairs.

Usage Notes

The Sorter may be useful for ordering features before using the PathBuilder.
It is possible to create self-intersecting paths with this transformer, which will not be rejected.
As the PathBuilder fills in gaps between features, it can produce unexpected results if the input features are not sorted correctly. To combine adjoining lines (without creating new geometry to connect gaps), use a LineCombiner (and ArcStroker, if arcs are present).
Aggregate geometry also treats multiple geometries as a single unit, but path geometry ensures that the components are contiguous and connected.
The PathSplitter will undo PathBuilder output.

Creating and Modifying Linear Features

These transformers work with lines in a variety of ways.

Line Transformers Comparison

	Function	Transformer Description
LineBuilder	Simple creation of lines from lines and/or points.	Connects sequential point and/or line features to create line or area geometry.
LineCombiner	Combining adjoining lines into longer lines or complex paths, with more advanced geometry handling options than the LineBuilder.	Connects line features that meet at common start or end points to create longer lines or paths.
PathBuilder	Combining arcs and lines into longer paths.	Connects sequential line and/or arc features to create path geometry, preserving input segments.
LineCloser	Converting linear features into areas.	Converts a linear feature to an area by connecting the end point to the start point.
LineExtender	Extending linear geometry.	Extends line, arc, or path features at both ends by a specified length.
Chopper	Chopping features into smaller features, breaking them at their existing vertices.	Chops line, arc, path, or area features into smaller features based on number of vertices or approximate length.
PathSplitter	Breaking a path into its component segments (lines and arcs).	Splits path geometry into its component line and/or arc segments.
Snipper	Shortening linear geometry.	Shortens linear geometry by cutting off the ends.
LineOnAreaOverlayer	Intersecting lines and areas.	Performs a line-on-area overlay, either splitting lines where they intersect area boundaries or subdividing areas where split by lines. Attributes may be shared between related lines and areas (spatial join).
LineOnLineOverlayer	Intersecting lines and lines.	Performs a line-on-line overlay in which all input lines are intersected against each other and resultant line features are created and output. Intersection points are turned into point features that can contain the merged list of attributes of the original intersected lines.
PointOnLineOverlayer	Finding where points lay on lines.	Performs a point-on-line overlay. Each input line is split at its closest place to any point within the specified point tolerance, and attributes may be shared between related points and lines (spatial join).

Configuration

Input Ports

Output Ports

Parameters

Group Processing

Group By

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.

The feature being created is output whenever a Group By value changes. When this happens, the feature with the differing attribute is not added to the current output feature; instead, it begins the next feature to be output.

Complete Groups

Select the point in processing at which groups are processed:

When All Features Received	This is the default behavior. Processing will only occur in this transformer once all input is present.
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.

General

Connect Z Mode

Where connection points have matching x and y coordinates but differing z values, select a method for handling z.

Connect Z Mode

When viewed in 2D (ignoring Z), a path (which may define the border of a polygon) may appear to be closed as shown in the left figure below. This same path, when viewed in 3D, may appear to be open as shown in the right figure below.

To specify how (and if) paths should be closed in 3D, select one of the listed modes.

Mode	Description	Example
Extend	The Curve is extended so that all vertices are left at their original location.
Average	Subsequent vertices that are not connected, but share an x and a y value are combined into one vertex, whose Z value is the average of the original two.
First Wins	Subsequent vertices that are not connected, but share an x and a y value are combined into one vertex, whose Z value is taken from the first encountered vertex.
Last Wins	Subsequent vertices that are not connected, but share an x and a y value are combined into one vertex, whose Z value is taken from the last encountered vertex.
Ignore	Z values are ignored. No change is made to the way the nodes are connected.

Aggregate Handling

Select how aggregate geometries are to be handled:

Deaggregate: Decompose aggregates into their individual components.
Reject: Do not process aggregates and output them via the <Rejected> port.

Attribute Accumulation

Generate List

When enabled:

List Name

Enter a List Name to be created on each output feature, containing attributes of each feature that was connected when creating the output path.

This parameter can also be used to preserve attributes from input features.

Note List attributes are not accessible from the output schema in FME Workbench unless they are first processed using a transformer that operates on them, such as ListExploder or ListConcatenator. Alternatively, AttributeExposer can be used.

Add To List

All Attributes: Every attribute from all input features that created an output feature will be added to the list specified in List Name.

Selected Attributes: Only the attributes specified in the Selected Attributes parameter will be added to the list specified in List Name.

Selected Attributes

The attributes to be added to the list when Add To List is Selected Attributes.

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

How to Set Parameter Values

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

Content Types

String Functions	These functions manipulate and format strings.
Special Characters	A set of control characters is available in the Text Editor.
Math Functions	Math functions are available in both editors.
Date/Time Functions	Date and time functions are available in the Text Editor.
Math Operators	These operators are available in the Arithmetic Editor.
FME Feature Functions	These return primarily feature-specific values.
FME Parameters	FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters	Create your own editable parameters.

Dialog Options - Tables

Table Tools

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

Add a row
Remove a row
Move current row up one
Move current row down one
Move current row to top
Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

Cut a row - delete and copy to clipboard
Copy a row to the clipboard
Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior	Group-Based
Feature Holding	Yes
Dependencies	None
Aliases
History

FME Community

The FME Community is the place for demos, how-tos, articles, FAQs, and more. Get answers to your questions, learn from other users, and suggest, vote, and comment on new features.

Search for all results about the PathBuilder on the FME Community.

Examples may contain information licensed under the Open Government Licence – Vancouver, Open Government Licence - British Columbia, and/or Open Government Licence – Canada.