Labeller

Places labels along a linear feature, angled to the orientation of each labeled segment.

Typical Uses

Annotating linear features

How does it work?

The Labeller receives linear features and generates text labels at intervals along them. Labels are rotated to match the orientation of the segment being labeled, with various size and position parameters.

Collision avoidance and minimum feature length for labeling are both available.

Label Orientation

The orientation of the text varies according to the orientation of the line segment it is placed on. Text is placed parallel to the line segment.

If the line angle produces text that is upside-down (that is, between 90 and 270 degrees), the text is rotated 180 degrees.

Both the line and text angles may be added as an output attribute.

Label Placement Interval and Starting Position

Label intervals are determined by the Label Spacing and Labels at End Points parameters.

If Label Spacing is zero (0), only one label is placed.

This input feature will be labeled with a Label Height of 8. It is 100 meters long.

Action	Parameters	Result
Place one label at the start of the feature.	Label Spacing: 0 Labels at End Points: Yes
Place one label at the midpoint of the feature.	Label Spacing: 0 Labels at End Points: No
Place labels every 40 meters, and at the first and last points of the feature.	Label Spacing: 40 Labels at End Points: Yes
Place labels every 40 meters, but not at the end points.	Label Spacing: 40 Labels at End Points: No

Label Positioning

When an offset is applied to labels, the Label Position parameter determines where label insertion points are placed relative to the feature.

Note that left and right are relative to direction of travel along the feature - they are not the left- and right-hand side of the field of view.

This input feature will be labeled. Note its orientation, indicated by the arrow.

The labels are placed with a large Label Offset value to illustrate position.

Label Position	Placement	Result
Above or Left	Label insertion points are placed above the feature. Where a line segment is vertical, labels are placed to the left, relative to the feature orientation.
Above or Right	Label insertion points are placed above the feature. Where a line segment is vertical, labels are placed to the right, relative to the feature orientation.
Below or Left	Label insertion points are placed below the feature. Where a line segment is vertical, labels are placed to the left, relative to the feature orientation.
Below or Right	Label insertion points are placed below the feature. Where a line segment is vertical, labels are placed to the right, relative to the feature orientation.
Left	All label insertion points are placed on the left-hand side, relative to the feature orientation.
Right	All label insertion points are placed on the left-hand side, relative to the feature orientation.

Usage Notes

Although area geometry is accepted, the labels are placed along the perimeter of the feature which may be undesirable. Consider using a LabelPointReplacer instead.
Point geometry will be rejected. Consider using a LabelPointReplacer or TextAdder.
Awkwardly angled labels might be improved by adjusting spacing or using a Generalizer on the input feature before labeling.

Creating and Modifying Point and Text Features

These transformers work with points, text, and labels in a variety of ways.

Points and Text Transformers Comparison

Transformer	Use this to...	Transformer Description
Creator	Create one or more new features with box geometry of a specific size and position (when Geometry Object is Point or Text).	Creates features using the parameters supplied, and sends them into the workspace for processing.
VertexCreator	Replace a feature’s geometry with a point at a specified location.	Creates a single vertex to replace, be appended to, or be inserted into existing geometry.
CenterPointReplacer	Create points inside features or their bounding boxes.	Replaces feature geometry with a point located within the feature, its bounding box, or at its center of mass.
CenterPointExtractor	Extract the coordinates of a calculated point within the feature.	Extracts the coordinates of a point located within the feature, its bounding box, or at its center of mass, and stores them as attributes.
2DGridCreator	Create new regularly-spaced points in a specified location.	Creates a regular grid of points or rectangular polygons of a specified size, position, and coordinate system.
2DGridAccumulator	Create new regularly-spaced points over the extents of other features.	Creates a regular grid of points or rectangular polygons that span the extents of all input features.
Chopper	Create points from every vertex of input line or area geometry.	Chops line, arc, path, or area features into smaller features based on number of vertices or approximate length.
Intersector	Create points where features intersect.	Computes intersections between all input features, breaking lines and polygons wherever an intersection occurs and creating nodes at those locations.
PointCloudToPointCoercer	Create points from point cloud features.	Converts point clouds to point or multipoint geometries, optionally retaining attribute and component values.
Labeller	Label lines.	Places labels along a linear feature, angled to the orientation of each labeled segment.
TextAdder	Label points at an angle.	Replaces any geometry with a single text label at the center of its bounding box.
LabelPointReplacer	Label points and areas.	Replaces point, line, or area geometry with a single text label.
TextLocationExtractor	Convert text to geometry.	Replaces text with its location geometry, usually a point.
TextPropertyExtractor	Extract text properties into attributes.	Retrieves text property values from text geometry, adding them to the feature as attributes.
TextPropertySetter	Set or modify text properties.	Modifies or creates text geometry according to new coordinates, text string, size, or rotation values.
TextStroker	Convert text to non-text geometry.	Converts text to aggregate line or area geometry according to a specific True Type font.
PointPropertyExtractor	Extract point properties into attributes.	Extracts point orientation to feature attributes.
PointPropertySetter	Set or modify point properties.	Adds or removes point orientation.

Labelling and Geometry

Geometry	Recommended Transformer	Example
Point	LabelPointReplacer or TextAdder
Line	Labeller
Area	LabelPointReplacer

Geometry

Recommended Transformer

Example

Point

LabelPointReplacer or TextAdder

Line

Labeller

Area

LabelPointReplacer

Configuration

Input Ports

Output Ports

Parameters

General

Label	Specify the label text string.
Prevent Label Overlaps	Select a method for handling overlapping labels: Yes: Labels that overlap a label already placed by the same transformer are discarded. No: All labels are placed regardless of overlaps.
Label Position	Select a method for placing label insertion points when Label Offset is greater than zero (0): Above or Left Above or Right Below or Left Below or Right Left Right See Label Positioning above. When Label Offset is zero (0), label points are placed on the feature. Regardless of insertion point position, the label text is placed above or to the right of the point. See Label Orientation above.
Label Offset	Specify the distance (in ground units) between the feature and the label insertion point. An offset of zero (0) places label points on the line.
Labels at End Points	Select an option for placing labels at the start and end points of the feature: Yes: Labels are generated at both ends, subject to the Prevent Label Overlaps parameter. No: The end points are not labeled. See Label Placement Interval and Starting Position above.
Label Height	Specify the height of the text in ground units.
Average Character Width	An average single character width (in ground units) may be specified to approximate the size of labels for a specific destination system or font. The default value is zero (0), which is interpreted as the width being equal to the Label Height. When Prevent Label Overlaps is Yes, the resulting dimensions (based on the label text) are used to determine if labels are kept or discarded to avoid collisions. Note that this setting does not alter how text is displayed in the FME Data Inspector, and the resulting labels may appear to overlap.
Label Spacing	Specify the interval (in ground units) at which labels should be placed, subject to the Prevent Label Overlaps and Labels at End Points parameters. If set to zero (0) a single label will be placed. See Label Placement Interval and Starting Position above.
Minimum Length	Specify the minimum length a feature must be in order to be labeled. The default is zero (0), which labels all features.

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

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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.