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Transformation - InterpolationSerial Linear

Description and usage

This transformation function is used to fill inner gaps in a time series. The inner gaps are filled with linearly interpolated data values.

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• inputVariable: A time series with input values. This will typically contain inner gaps.
• outputVariable: A time series in which the output will be stored. The output series will contain all input values and the inner gaps will be filled.

The in- and output time series may be of the type coverage, where each timestep is represented by a grid coverage, in this case coverages that are missing for a specific timestep will be created by interpolation of the previous and next available coverage. Optionally, you can enable interpolation of missing pixels within the coverages by specifying the option <interpolateGrids> as true.

Configuration

A basic configuration of the function is described below. This describes the main elements and attributes required and provides an example configuration.

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maxGapLength
Optional element defining the maximum length of gaps that should be filled. The length is equal to the number of time steps. Gaps equal to or smaller than maxGapLength will be filled with interpolated values. Gaps larger than maxGapLength will not be filled. If maxGapLength is not defined (the default), then all gaps will be filled with interpolated values.

interpolateMissingGridCells
Since 2022.01: Optional element that can be set to 'true' to enable the interpolation of missing grid cells (pixels) for grid coverage time series (default is false). When using this option it is recommended to specify the maxGapLengthas the default maxGapLength value of 1 time step will be used otherwise. Note that this default behavior is different from the standard maxGapLength default behavior explained, in order to prevent excessive memory use for this interpolation.

outputCustomFlagSourceIdoutputFlagSource
Optional element to define what customFlagSource should be written to which flagSourceColumn the flagSourceColumn (defined in the workflow file) for interpolated values. The customFlagSourceId should be configured in CustomFlagSources configuration file. The flagSourceColumnId should be configured in the FlagSourceColumns configuration file. . 

outputComment if outputCustomFlagSourceId is being used, then the outputComment is added for the missing values. For the available values, the input comments would be used.

Example

<transformation id="interpolation serial linear">
	<interpolationSerial>
		<linear>
			<inputVariable>
				<variableId>input</variableId>
			</inputVariable>
			<maxGapLength>5</maxGapLength>
			<interpolateMissingGridCells>false</interpolateMissingGridCells>
            <outputVariable>
				<variableId>output</variableId>
			</outputVariable>
			<outputComment>outputCommentTest</outputComment>
            <outputFlagSource flagSourceColumnId="A" customFlagSourceId="SG" /><outputCustomFlagSourceId>INTP</outputCustomFlagSourceId>
		</linear>
	</interpolationSerial>
</transformation>

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