RasterCellValueCalculator

Evaluates basic arithmetic , minimum, maximum or average operations on the cell values of a pair of rasters.

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Typical Uses

  • Recalculating raster cell values by processing them individually against another raster

How does it work?

The RasterCellValueCalculator receives pairs of raster features, and evaluates a defined arithmetic expression on the band values of each pair of corresponding cells.

Each pair of rasters must have:

  • the same number of rows and columns
  • the same number of bands (or selected bands)
  • the same nodata value, or have no nodata value

The rasters are routed into A and B input ports, and an Operation is selected to perform, constructing a basic expression in the form A <operation> B. Operations available include addition, subtraction, multiplication, division, and three basic statistics - minimum, maximum, and average. The order of A and B is fixed, and matters for certain operations including division and subtraction.

The new values are output on the same band from which they were calculated. Preserve Interpretation determines whether or not the band is converted to a different type on output - for example, the division of two integers may produce a floating-point decimal result, converting the output band to interpretation type real64.

If the rasters are mismatched either in dimension (number of rows and columns) or number of bands (or selected bands), an error will occur.

Position information for georeferenced rasters is not taken into consideration.

For multi-band rasters, the first selected band of raster A is combined with the first selected band of raster B, the second selected band of raster A is combined with the second selected band of raster B, and so on. To restrict operation to specific band(s), use a RasterSelector prior to the RasterCellValueReplacer.

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

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.