FME Transformers: 2024.1

Categories
Rasters
Related Transformers
RasterCellValueCalculator
RasterCellValueReplacer
RasterCellValueRounder
RasterExpressionEvaluator
RasterSingularCellValueCalculator
RasterStatisticsCalculator

RasterConvolver

Applies a convolution filter (sometimes called a kernel or lens) to raster features and outputs the results.

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Typical Uses

  • Image manipulation
  • Raster data analysis
  • Smoothing, blurring, or sharpening an image
  • Edge detection
  • Reducing image “noise” (to help with future feature detection)
  • Calculate slopes in a raster DEM

How does it work?

The RasterConvolver receives raster features and applies convolution filters to them, then outputs the modified rasters.

Convolution is a mathematical operation carried out on two objects in order to create a third. In this transformer, the first object is a raster feature and the second object is a raster-like matrix of numbers. The operation can be one of many common mathematical operations.

Processing the raster feature against the matrix, using the specified operator, returns a new raster feature with new qualities. Such filtering is used for smoothing, sharpening, enhancing edges and other raster image manipulation operations.

Convolution filters are defined by a kernel (specified by a matrix of weights) and a mathematical operation. The filter is applied, in turn, to each of the cells of the input raster. Each cell is given a new value according to the result of the mathematical operation on the cell and its neighbors, using the matrix of weights.

A selection of predefined Convolution Filters is available, and kernels may be modified or completely user-defined. Options are available for edge and Nodata handling.

This transformer supports raster band selection. The RasterSelector can be used to modify the selection. Palettes are not supported.

Examples

Usage Notes

Choosing a Raster Transformer

FME has an extensive selection of transformers for working with raster data. They can be generally categorized as working with whole rasters, bands, cells or palettes, and those designed for workflow control or combining raster with vector data.

For information on raster geometry and properties, see Rasters (IFMERaster).

Configuration

Input Ports

Output Ports

Parameters

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.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior

Feature-Based

Feature Holding

No

Dependencies None
Aliases RasterLensProcessor
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.