PointOnLineOverlayer

Example: Overlaying points on lines

In this example, we perform an overlay of rapid transit stations points on rapid transit lines. The source data, as seen here, contains three individual transit routes, each one a single line feature.

The station points are close to the lines, but not right on them - generally within a meter.

The stations are connected to the Point input port, and the routes are connected to the Line input port.

In the parameters dialog, we enter a tolerance of “5” - meaning 5 meters, as these datasets are in a UTM projection, with ground units in meters. We also choose to merge attributes.

The transit lines are split where they encounter a station within the specified tolerance, as shown here by randomly coloring the output line features. Attributes are shared between the points and lines, as in these point attributes for Renfrew Station, which now has a new attribute indicating that it overlaid the Millennium Line.

Output Lines receive attributes from all of the points that the original unchopped line encountered - see Usage Notes for more detail.

Spatial Transformers Comparison

Transformer	Can Merge Attributes	Alters Geometry	Counts Related Features	Creates List	Supported Types*	Recommended For
SpatialFilter	Yes	No	No	No	Point Text Curve Area	Testing for the existence of spatial relationships between two sets of features, and routing them according to whether they pass or fail the test(s).
SpatialRelator	Yes	No	Yes	Yes	Point Text Curve Area	Identifying the nature of spatial relationships between two sets of features.
AreaOnAreaOverlayer	Yes	Yes	Yes	Yes	Area	Finding polygon overlaps and extracting them into new geometry.
LineOnAreaOverlayer	Yes	Yes	Yes	Yes	Curve and Area	Finding intersections between lines and polygons, splitting either where they intersect.
LineOnLineOverlayer	Yes	Yes	Yes	Yes	Curve	Finding intersections between line features, splitting them, and generating new line geometry as well as points representing the intersections.
PointOnAreaOverlayer	Yes	No	Yes	Yes	Point and Area Text and Area	Identifying points that fall within polygons, and merging attributes between them
PointOnLineOverlayer	Yes	Yes	Yes	Yes	Point and Curve Text and Curve	Identifying where points fall on lines, and splitting the lines into new geometry.
PointOnPointOverlayer	Yes	No	Yes	Yes	Point Text	Identifying points in the same location (within a tolerance), and merging attributes between them.
Intersector	Yes	Yes	Yes	Yes	Point Text Curve Area	Finding intersections between all input features, regardless of geometry (including self-intersections), splitting features, and creating new geometry.
Clipper	Yes	Yes	No	No	Point Text Curve Area Surface Solids Raster Point Cloud	Comparing features against a set of Clipper features, and splitting the features at or along the Clipper boundaries. Outputs both new and untouched geometry, identified as either Inside or Outside the Clipper.
NeighborFinder	Yes	In some cases	No	Yes	Point Text Curve Area	Identifying the nearest other feature(s) to each feature being considered, either in another set of features or within the same feature set.
TopologyBuilder	Yes	Yes	No	Yes	Point Text Curve Area	Analyzing spatial relationships between features to compute topology, splitting features and creating new geometry representing topologically significant nodes, edges, and faces, with associated attributes.

* Note that Curve includes Lines, Arcs, and Paths. Area includes Polygons, Donuts, and Ellipses.

The Effect of Spatial Transformer Choice on Performance

Spatial analysis can be processing-intensive, particularly when a large number of features are involved. If you would like to tune the performance of your workspace, this is a good place to start.

When there are multiple ways to configure a workspace to reach the same goal, it is often best to choose the transformer most specifically suited to your task.

If performance is an issue in your workspace, look for alternative methods, guided by geometry.

Point

Point features against which the lines will be compared.

Line

Line features against which the points will be compared.

Point

Point features, with attributes added according to transformer parameter configuration. Geometry is unmodified, unless z-values have been extracted from lines.

Line

Line features which have been split at the location closest to matching points, with attributes added according to transformer parameter configuration.

Features with invalid geometries will be rejected and output via this port.

Rejected features will have an fme_rejection_code attribute with one of the following values:

INVALID_POINT_GEOMETRY_TYPE
INVALID_LINE_GEOMETRY_TYPE
INVALID_LINE_GEOMETRY_VERTICES
INVALID_GEOMETRY_DEGENERATE

Rejected Feature Handling: can be set to either terminate the translation or continue running when it encounters a rejected feature. This setting is available both as a default FME option and as a workspace parameter.

Group Processing

Group By

The default behavior is to use the entire set of features as the group. This option allows you to select attributes that define which groups to form.

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

Point Tolerance

The Point Tolerance value is compared to the distance from the lines to the points, and the lines will be segmented if the distance is less than or equal to the Point Tolerance value. When such a match occurs, the attributes of the segmented lines are merged with the points and the attributes of the points are merged with the lines.

See Geometry Concepts > Tolerance.

Aggregate Handling

Choose 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.

Merge Measures

If Yes, any measures that exist on a line will be added to matching points. Measure values are determined according to the Treat Measures As parameter.

If both point and line have measures of the same name, the point's values will be overwritten by the line's values.

If No, no measures will be copied, and any existing measures (on points or lines) will be output unchanged.

Treat Measures As

This parameter determines how measures are computed:

at new intersection locations on lines, and
when adding measures to points if Merge Measures is Yes.

Continuous: The new measure value will be calculated, interpolating based on the nearest measures.

Discrete: The new measure value will be copied from the nearest measure.

Attribute Accumulation

If attributes on the incoming and original feature share the same name, but are not geometry attributes that start with fme_, then they are deemed conflicted.

Note On the PointOnLineOverlayer, Attribute Accumulation applies to the measures on a point in a similar way to how it applies to the attributes on a feature.

If measures on the point and line share the same name, then they are deemed conflicted.

The resolution of conflicted measures on points occurs in the same manner as the resolution of conflicted attributes on features. It is resolved according to the Accumulation Mode and Conflict Resolution values.

Merge Attributes

Accumulation Mode

Merge Incoming: The original feature will retain all of its own un-conflicted attributes, and will additionally acquire any un-conflicted attributes that the incoming feature has. This mode will handle conflicted attributes based on the Conflict Resolution parameter.

Prefix Incoming: The original feature will retain all of its own attributes. In addition, the original will acquire attributes reflecting the incoming feature’s attributes, with the name prefixed with the Prefix parameter.

Replace with Single Incoming: The original feature will have all of its attributes removed, except geometry attributes that start with fme_. Then, all of the attributes from one (arbitrary) incoming feature will be placed onto the original.

Conflict Resolution

Use Original: If a conflict occurs, the original values will be maintained.

Use Incoming: If a conflict occurs, the values of the incoming will be transferred onto the original.

Prefix

If the Accumulation Mode parameter is set to Prefix Incoming, this value will prefix attributes and measures that are being added to the original feature from the incoming feature.

Generate List on Output ‘Point’

When enabled, adds a list attribute to the Point output features, and the attributes of each line matching an output point are added to that point's list.

‘Point’ List Name

Enter a name for the list attribute.

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 'Point' List

All Attributes: All attributes will be added to the output Point features.

Selected Attributes: Enables the Selected Attributes parameter, where specific attributes may be chosen for inclusion.

Selected Attributes

Enabled when Add To 'Point' List is set to Selected Attributes. Specify the attributes you wish to be included.

Generate List on Output ‘Line’

When enabled, adds a list attribute to the Line output features, and the attributes of each point matching an original input line are added to each output line created from it.

‘Line’ List Name

Enter a name for the list attribute.

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 'Line' List

All Attributes: All attributes will be added to the output Line features.

Selected Attributes: Enables the Selected Attributes parameter, where specific attributes may be chosen for inclusion.

Selected Attributes

Enabled when Add To 'Line' List is set to Selected Attributes. Specify the attributes you wish to be included.

Output Attribute Name

Overlap Count

The Overlap Count Attribute added to output linear features holds the number of point features that were near to it.

The Overlap Count Attribute added to output point features holds the number of linear features that the point was near to.

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.

Processing Behavior	Group-Based
Feature Holding	Yes
Dependencies
Aliases
History

PointOnLineOverlayer

Typical Uses

How does it work?

Examples

Usage Notes

Z Values and Measures

Choosing a Spatial Transformer

Configuration

Input Ports

Output Ports

Parameters

Editing Transformer Parameters

Reference

FME Community