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PointOnRasterValueExtractor

Extracts the band and palette values from a raster at the location of each input point and sets them as attributes on the feature.

The following band and palette properties are exposed:

_band{}.value

_band{}.palette{}.value

Note: Wherever "{}" appears, there will be one instance of the attribute for each band or palette. The first will appear with {0}, the second with {1}, and so on.

Note that no attributes will be set for points outside the reference raster extents.

Parameters

Transformer

ClosedGroup By

The points may be organized into groups with the Group By parameter, with each group of points having its own reference raster.

ClosedParallel Processing

Note: How parallel processing works with FME: see About Parallel Processing for detailed information.

This parameter determines whether or not the transformer should perform the work across parallel processes. If it is enabled, a process will be launched for each group specified by the Group By parameter.

Parallel Processing Levels

Parameter Number of Processes
No Parallelism 1
Minimal coresThe processor, or CPU, is the physical part of the computer that performs mathematical calculations. It is the most important part of a computer system. Traditional processors have only one core on the processor, meaning that at any given time, only one set of calculations is being performed. If a processor is dual-core, this means the single chip contains hardware for two processors, now called cores to distinguish them from the single chip, running simultaneously, side by side. (Source: http://www.ehow.com/facts_5730257_computer-core-processors_.html) / 2
Moderate exact number of cores
Aggressive cores x 1.5
Extreme cores x 2

For example, on a quad-core machine, minimal parallelism will result in two simultaneous FME processes. Extreme parallelism on an 8-core machine would result in 16 simultaneous processes.

You can experiment with this feature and view the information in the Windows Task Manager and the Workbench Log window.

ClosedInput Ordered

No: This is the default behavior. Processing will only occur in this transformer once all input is present.

By Group: This transformer will process input groups in order. Changes on the value of the Group By parameter on the input stream will trigger batch processing on the currently accumulating group. This will improve overall speed if groups are large/complex, but could cause undesired behavior if input groups are not truly ordered.

Parameters

ClosedInterpolation Type

This parameter determines the interpolation method to be used when retrieving raster values from points.

Nearest Neighbor interpolation is the fastest and least accurate, while Bilinear and Bicubic are slower but will weight surrounding data values into the final result. Average 4 and Average 16 have a performance similar to Bilinear and are useful for numeric rasters such as DEMs.

Example

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.

Transformer Categories

Rasters

Spatial Analysis

FME Licensing Level

FME Professional edition and above

Transformer History

This transformer was previously named PointOnRasterOverlayer.

 

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Tags Keywords: raster band palette vector overlay point interpolate vectorization vectorisation PointOnRasterOverlayer