Chopper

Chops line, arc, path, or area features into smaller features based on number of vertices or approximate length.

Typical Uses

Chopping features into individual points
Chopping features into a series of two-point lines
Chopping features to work with formats that have limits on the number of coordinates per feature

How does it work?

The Chopper receives vector features including lines, arcs, paths, and areas, and breaks them into smaller pieces. Attributes are preserved on all output features.

New vertices are not added to the feature. Chopping is done at existing vertices, guided by a choice of Mode:

By Vertex: Features are chopped at the interval specified in Maximum Vertices. Output features with fewer vertices than the maximum are tagged as remnants (generally the last segment).
By Length: An Approximate Length is specified, in ground units. The input features are chopped into segments as close as possible to this length, without adding new vertices. Output feature lengths will vary, depending on the length value and distance between vertices on the feature.

Action	Values	Result
None (Input Feature)
Chop into single points.
Chop into two-point lines.
Chop into four-point lines - note the last segment is a remnant.
Chop by a length that coincides with vertex locations.
Chop by a length that does not coincide with vertex locations. Note that the nearest vertex is the chopping location.

Chopped features are output via the Chopped output port. Untouched features exit via Untouched.

Arcs are stroked prior to determining chopping locations. They are output as line segments if chopped, and as the original arc if untouched.

Input features with point geometry are unaltered and passed through the Untouched output port.

Z values are preserved.

Usage Notes

The Densifier may be useful in preparing to chop by length.

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

General

Mode	Select a method for chopping: By Vertex: Chop features according to number of vertices. By Length: Chop features by approximate length, varying according to vertex positions.
Maximum Vertices	When Mode is By Vertex, specify the interval for chopping by number of vertices. Remnants may be produced at the end of features with fewer vertices than the maximum specified.
Approximate Length	When Mode is By Length, specify a target length for chopping, in ground units.
Add Interior Vertices (Areas Only)	Not in use.
Aggregate Handling	Select a method for handling input features with aggregate geometry: Deaggreate the feature and process them. Reject the features.

Advanced

Preserve Feature Order

This parameter controls the order in which features exit a transformer.

When a transformer has more than one output port, features usually exit one port at a time. At times, it may be useful to keep the order that features arrived in, switching from port to port as necessary. This allows feature order to be preserved, though at a potential cost in processing efficiency.

Select a method for feature ordering.

Per Output Port (Default)

Only preserve the input order of features as they occur within the group of features exiting a given output port.

All features exiting an output port retain their ordering relative to each other (within the group), but not relative to features exiting other output ports.

This option is generally the most efficient, where large chunks of features will exit an output port together (taking advantage of bulk mode).

As features exiting different output ports may not be strictly output in the order they arrived, output ordering may be unpredictable.

Across Output Ports

Strictly preserve the input order of features, regardless of which output port they exit. Features will be output singly in the same order they arrived, switching from port to port as necessary. This option is generally less efficient as the processing gains of bulk mode are less likely to apply - however, feature order is predictable.

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	Feature-Based
Feature Holding	No
Dependencies	None
Aliases
History

FME Community

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