Package org.esa.snap.core.gpf.common

Class BandMathsOp

java.lang.Object
org.esa.snap.core.gpf.Operator
org.esa.snap.core.gpf.common.BandMathsOp
@OperatorMetadata(alias="BandMaths", category="Raster", version="1.1", copyright="(c) 2013 by Brockmann Consult", authors="Marco Zuehlke, Norman Fomferra, Marco Peters", description="Create a product with one or more bands using mathematical expressions.") public class BandMathsOp extends Operator

This band maths operator can be used to create a product with multiple bands based on mathematical expression.
All products specified as source must have the same width and height, otherwise the operator will fail. The geo-coding information and metadata for the target product is taken from the first source product.

To reference a band of one of the source products within an expression use the following syntax:

$sourceProduct.#.bandName

Where # means the index of the source product. The index is zero based.
The bands of the first source product ($sourceProduct.0) can be referenced without this product identifier. The band name is sufficient.

When using this operator from the command-line Graph XML file must be provided in order to specify all parameters. Here is some sample XML of how to use a BandMaths node within a graph: 

      <node id="bandMathsNode">
        <operator>BandMaths</operator>
        <sources>
            <sourceProducts>readNode</sourceProducts>
        </sources>
        <parameters>
            <targetBands>
                <targetBand>
                    <name>reflec_13</name>
                    <expression>radiance_13 / (PI * SOLAR_FLUX_13)</expression>
                    <description>TOA reflectance in channel 13</description>
                    <type>float32</type>
                    <validExpression>reflec_13 >= 0</validExpression>
                    <noDataValue>-999</noDataValue>
                    <spectralBandIndex>13</spectralBandIndex>
                </targetBand>
                <targetBand>
                    <name>reflec_14</name>
                    <expression>radiance_14 / (PI * SOLAR_FLUX_14)</expression>
                    <description>TOA reflectance in channel 14</description>
                    <type>float32</type>
                    <validExpression>reflec_14 >= 0</validExpression>
                    <noDataValue>-999</noDataValue>
                    <spectralBandIndex>14</spectralBandIndex>
                </targetBand>
            </targetBands>
            <variables>
                <variable>
                    <name>SOLAR_FLUX_13</name>
                    <type>float32</type>
                    <value>914.18945</value>
                </variable>
                <variable>
                    <name>SOLAR_FLUX_14</name>
                    <type>float32</type>
                    <value>882.8275</value>
                </variable>
                 <variable>
                    <name>PI</name>
                    <type>double</type>
                    <value>3.1415</value>
                </variable>
            </variables>
        </parameters>
    </node>

Changes from version 1.0 to 1.1:

  1. Added setter and getter methods for parameters
  2. Changed type of BandDescriptor.noDataValue from String to Double
  3. Deprecated API method 'createBooleanExpressionBand'
Since:
BEAM 4.7

  • Constructor Details

    • BandMathsOp

      public BandMathsOp()

  • Method Details

    • getTargetBandDescriptors

      public BandMathsOp.BandDescriptor[] getTargetBandDescriptors()

    • setTargetBandDescriptors

      public void setTargetBandDescriptors(BandMathsOp.BandDescriptor... targetBandDescriptors)

    • getVariables

      public BandMathsOp.Variable[] getVariables()

    • setVariables

      public void setVariables(BandMathsOp.Variable... variables)

    • initialize

      public void initialize() throws OperatorException
      Description copied from class: Operator
      Initializes this operator and sets the one and only target product.

      The target product can be either defined by a field of type Product annotated with the TargetProduct annotation or by calling Operator.setTargetProduct(org.esa.snap.core.datamodel.Product) method.

      This method shall never be called directly. The framework calls this method after it has created an instance of this Operator. This will occur only once durting the lifetime of an Operator instance. If not already done, calling the Operator.getTargetProduct() will always trigger a call to the initialize() method.

      Any client code that must be performed before computation of tile data should be placed here.

      Specified by:
      initialize in class Operator
      Throws:
      OperatorException - If an error occurs during operator initialisation.
      See Also:

    • computeTile

      public void computeTile(Band band, Tile targetTile, ProgressMonitor pm) throws OperatorException
      Description copied from class: Operator
      Called by the framework in order to compute a tile for the given target band.

      The default implementation throws a runtime exception with the message "not implemented".

      This method shall never be called directly.

      Overrides:
      computeTile in class Operator
      Parameters:
      band - The target band.
      targetTile - The current tile associated with the target band to be computed.
      pm - A progress monitor which should be used to determine computation cancellation requests.
      Throws:
      OperatorException - If an error occurs during computation of the target raster.