RasterResampler
Resamples rasters, based on specified output dimensions, cell size in ground units, or percentage of original, by interpolating new cell values.
Jump to Configuration
Typical Uses
How does it work?
The RasterResampler accepts raster features and alters the number of rows/columns and resizes cell (pixel) size according to the parameter selections. One raster feature is output for each input feature.
Output raster resolution may be specified by set dimensions (columns and rows), cell size in ground units, or percentage of original resolution.
A variety of methods are available for output cell value interpolation.
This transformer is unaffected by raster band and palette selection.
A: Original resolution
B: Desired resolution
C: Desired resolution compared to original
D: Resampled output raster
Example: Resampling a raster based on cell size
In this example, we will resample an orthophoto. The original raster is 1600 x 1000 pixels, with a cell size (Spacing) of 1,1 - one meter wide by one meter high (the ground units of the projection).
The raster is routed into a RasterResampler.
In the parameters dialog, we select the Size Specification of CellSize. This enables the X and Y Cell Spacing parameters, which are then both set to 25 - meaning 25 meters in ground units.
Interpolation Type is left as the default of Nearest Neighbor.
The output raster covers the same geographic extents as the input, but the cells are now 25 meters square and the resolution has correspondingly decreased to 64 x 40.
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).
Raster Transformers
Working with Rasters
These transformers generally apply to whole rasters.
RasterCellOriginSetter
|
Sets the cell origin point within cells in a raster.
|
RasterConvolver
|
Applies a convolution filter (sometimes called a kernel or lens) to raster features and outputs the results.
|
RasterExpressionEvaluator
|
Evaluates expressions on each cell in a raster or pair of rasters, including algebraic operations and conditional statements.
|
RasterExtentsCoercer
|
Replaces the geometry of input raster features with a polygon covering either the extents of a raster or the extent of data within a raster.
|
RasterGCPExtractor
|
Extracts Ground Control Point (GCP) coordinate system and point values from a raster feature and exposes them as attributes.
|
RasterGCPSetter
|
Sets Ground Control Points (GCPs) on a raster, pairing cell positions with known coordinates.
|
RasterGeoreferencer
|
Georeferences a raster by either known corner coordinates or origin, cell size, and rotation.
|
RasterHillshader
|
Generates a grayscale shaded relief representation of terrain, based on elevation values.
|
RasterInterpretationCoercer
|
Alters the interpretation type of rasters, including all bands, and converts cell values if necessary.
|
RasterMosaicker
|
Merges multiple raster features into a single raster feature.
|
RasterPropertyExtractor
|
Extracts the geometry properties of a raster feature and exposes them as attributes.
|
RasterPyramider
|
Resamples rasters to multiple resolutions, based on either number of levels or dimensions of the smallest output raster. |
RasterRegisterer
|
Transforms an image to minimize its difference with another.
|
RasterResampler
|
Resamples rasters, based on specified output dimensions, cell size in ground units, or percentage of original, and interpolates new cell values.
|
RasterRotationApplier
|
Rotates a raster feature according to its rotation angle property, interpolating new cell values, updating all other affected raster properties, and producing an output raster feature with a rotation angle of zero.
|
RasterSharpener
|
Enhances the features of a raster image. The RasterSharpener enhances the borders, lines, and curves while reducing noise in the flat areas of the raster image. |
RasterSubsetter
|
Clips raster features using pixel bounds instead of ground coordinates, and optionally adds cells around the perimeter.
|
RasterTiler
|
Splits each input raster into a series of tiles by specifying either a tile size in cells/pixels or the number of tiles.
|
RasterToPolygonCoercer
|
Creates polygons from input raster features. One polygon is output for each contiguous area of pixels with the same value in the input raster.
|
WebMapTiler
|
Creates a series of image tiles that can be utilized by web mapping applications such as Bing™ Maps, Google Maps™, or Web Map Tile Service. This is done by resampling rasters to various different resolutions and then splitting them into tiles.
|
Working with Bands
Working with Cells
Working with Palettes
Workflow Control
These transformers generally control the flow of features in a workspace.
RasterCheckpointer
|
Forces accumulated raster operations to be processed, saving the state to disk and releasing resources to tune performance or assist with memory limitations. |
RasterConsumer
|
Reads raster features for testing purposes, including any accumulated raster operations. No additional operations are performed, and nothing is done with the features. |
RasterExtractor
|
Serializes the geometry of a raster feature into a Blob attribute, encoding the contents according to a choice of common binary raster formats.
|
RasterNumericCreator
|
Creates a numeric raster of specified size and resolution, with default cell values.
|
RasterReplacer
|
Decodes a binary attribute containing encoded rasters stored as Blobs, replacing the feature’s geometry with the decoded raster.
|
RasterRGBCreator
|
Creates a color raster feature of specified size, resolution, and interpretation type, with default cell values.
|
RasterSelector
|
Selects specific bands and palettes of a raster for subsequent transformer operations.
|
Vectors and Rasters
These transformers generally involve using rasters and vector data together.
ImageRasterizer
|
Creates a raster representation of vector or point cloud input features, using the fme_color attribute over a solid background fill for vector features. Point clouds may be rendered using their color or intensity components.
|
NumericRasterizer
|
Creates a numeric raster representation of vector or point cloud input features, where cell values are taken from the z coordinates of the input features and overlaid on a uniform background.
|
MapnikRasterizer
|
Generates a raster from input vector and raster features, with fine control over symbolization and labeling, using the Mapnik toolkit.
|
PointOnRasterValueExtractor
|
Extracts the band and palette values from a raster at the location of one or more input points and sets them as attributes on the feature. |
RasterDEMGenerator
|
Produces a raster digital elevation model (DEM) by uniformly sampling a Delaunay triangulation generated from input points and breaklines. |
VectorOnRasterOverlayer
|
Rasterizes vector or point cloud features onto an existing raster. For vector features the fme_color attribute sets pixel color, and point clouds may be rendered using their color or intensity components.
|
Configuration
Input Ports
Input
This transformer accepts only raster features.
Output Ports
Resampled
One resampled raster per input raster feature.
<Rejected>
Non-raster features will be routed to the <Rejected> port, as well as invalid rasters.
Rejected features will have an fme_rejection_code attribute with one of the following values:
INVALID_GEOMETRY_TYPE
INVALID_RASTER_NO_BANDS
INVALID_PARAMETER_NUMBER_OF_ROWS
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.
Parameters
Raster Size
Size Specification
|
Select a method for specifying output raster size. Options include:
RowsColumns
|
Define the resolution of the output raster by number of rows and columns, and calculate the corresponding appropriate cell size.
|
CellSize
|
Define the resolution of the output raster by desired cell (pixel) size, and calculate the corresponding appropriate number of rows and columns.
|
Percentage
|
Calculate resolution and cell size as a percentage of the input feature’s original size.
|
|
Number of Columns (cells)
|
If Size Specification is RowsColumns, specify the desired raster width in cells (pixels).
|
Number of Rows (cells)
|
If Size Specification is RowsColumns, specify the desired raster height in cells (pixels).
|
X Cell Spacing
|
If Size Specification is CellSize, specify the desired cell (pixel) width in ground units.
|
Y Cell Spacing
|
If Size Specification is CellSize, specify the desired cell (pixel) height in ground units.
|
Percentage
|
If Size Specification is Percentage, specify the desired percentage. This number must be greater than 0, and may be greater than or less than 100.
100 is equal to the input size.
|
Interpolation
Interpolation Type
|
Cell values are interpolated to produce various raster sizes and resolutions. Choose a method:
Nearest Neighbor
|
The simplest and fastest method. Values are copied from the nearest cell. |
Bilinear
|
Calculates a weighted average, adjusted for distance, from the four (4) nearest cells.
|
Bicubic
|
Calculates a weighted average, adjusted for distance, from the sixteen (16) nearest cells.
|
Average 4
|
Calculates a simple average from the four (4) nearest cells.
Similar to Bilinear and is useful for numeric rasters such as DEMs.
|
Average 16
|
Calculates a simple average from the sixteen (16) nearest cells.
Similar to Bicubic and is useful for numeric rasters such as DEMs.
|
|
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.
How to Set Parameter Values
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.
Reference
Processing Behavior
|
Feature-Based
|
Feature Holding
|
No
|
Dependencies |
None |
FME Licensing Level
|
FME Professional Edition and above
|
Aliases |
|
History |
|
Categories |
Rasters
|
FME Community
The FME Community is the place for demos, how-tos, articles, FAQs, and more. Get answers to your questions, learn from other users, and suggest, vote, and comment on new features.
Search for all results about the RasterResampler on the FME Community.
Examples may contain information licensed under the Open Government Licence – Vancouver