RubberSheeter

Variably adjusts vector feature coordinates based on their proximity to control vectors indicating current and desired positions.

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Typical Uses

  • Applying positional corrections when the modifications are not consistent across the dataset.

How does it work?

The RubberSheeter receives two types of features - those to be adjusted (Observed) and those that describe how that adjustment is done (Control vectors and Constraints).

Observed features can have any type of vector geometry.

Most Control vectors have two points. The start point is located somewhere in the Observed features’ space, and the end point is the desired new location of that point.

A Control vector with only one point indicates that a location should not move - often called a tie point.

Each vertex is modified differently, depending on how close it is to nearby Control vectors (using inverse distance weighting). Only Control vectors that start within the specified Max Distance are used to calculate the new position. This can result in part of a feature being transformed and part of it remaining as is.

Constraints are optional. These lines are treated as boundaries, across which Control vectors will have no influence. If the line of sight from a point on an Observed feature to the starting point of a Control vector crosses a Constraint line, that Control vector will not affect the point in question. If the line of sight touches the end of a Constraint line, or either the Control vector or Observed point is actually located on the Constraint line, the Control vector will influence the observed point.

The modified Observed features are output via the Corrected port. Control vectors and Constraints are discarded.

                

Usage Notes

  • The AffineWarper transformer provides similar functionality but computes an affine transformation (scale, rotation, and offset) based on Control vector features and applies this transformation to the Observed features. This is more appropriate for cases when the entire set of Observed data requires a single, consistent transformation.

  • Raster geometry is not supported.

Configuration

Input Ports

Output Ports

Parameters

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

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. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Dialog Options - Tables

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

Reference

Processing Behavior

Group-Based

Feature Holding

Yes

Dependencies None
Aliases  
History  

FME Community

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