BandMaths¶

In [1]:

from snapista import Graph
from snapista import Operator
from snapista import TargetBand
from snapista import TargetBandDescriptors

The BandMaths operator creates TargetBands

In [2]:

band_maths = Operator('BandMaths')

In [3]:

band_maths.describe()

Operator name: BandMaths

Description: Create a product with one or more bands using mathematical expressions.
Authors: Marco Zuehlke, Norman Fomferra, Marco Peters

org.esa.snap.core.gpf.common.BandMathsOp
Version: 1.1

Parameters:

	targetBandDescriptors: List of descriptors defining the target bands.
		Default Value: None

		Possible values: []

	variables: List of variables which can be used within the expressions.
		Default Value: None

		Possible values: []

The XML representation of a targetBand is:

<targetBand>
          <name>active_fire_detected</name>
          <type>float32</type>
          <expression>S9_BT_in &lt; 265 ? 0 : F1_BT_in &gt; 315 and (F1_BT_in - F2_BT_in) &gt; 15 ? 1 : 0</expression>
          <description/>
          <unit/>
          <noDataValue>NaN</noDataValue>
</targetBand>

With snapista a targetBand is created with:

In [4]:

active_fire_band = TargetBand(name='active_fire_detected',
                              expression='S9_BT_in < 265 ? 0 : F1_BT_in > 315 and (F1_BT_in - F2_BT_in) > 15 ? 1 : 0')

In [5]:

active_fire_band

Out[5]:

TargetBand(name='active_fire_detected', expression='S9_BT_in < 265 ? 0 : F1_BT_in > 315 and (F1_BT_in - F2_BT_in) > 15 ? 1 : 0', type='float32', description=None, unit=None, no_data_value='NaN')

And associated to the BandMaths operator with:

In [6]:

band_maths.targetBandDescriptors = TargetBandDescriptors([active_fire_band])

A complete graph is thus done with:

In [7]:

g = Graph()

g.add_node(operator=Operator('Read'), 
           node_id='read_1')

In [8]:

g.add_node(operator=band_maths, 
           node_id='band_maths', 
           source='read_1')

In [9]:

g.view()

<graph>
  <version>1.0</version>
  <node id="read_1">
    <operator>Read</operator>
    <sources/>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <bandNames/>
      <copyMetadata>true</copyMetadata>
      <file/>
      <formatName/>
      <geometryRegion/>
      <maskNames/>
      <pixelRegion/>
    </parameters>
  </node>
  <node id="band_maths">
    <operator>BandMaths</operator>
    <sources>
      <sourceProduct refid="read_1"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <targetBands>
        <targetBand>
          <name>active_fire_detected</name>
          <expression>S9_BT_in &amp;lt; 265 ? 0 : F1_BT_in &amp;gt; 315 and (F1_BT_in - F2_BT_in) &amp;gt; 15 ? 1 : 0</expression>
          <type>float32</type>
          <description/>
          <unit/>
          <no_data_value>NaN</no_data_value>
        </targetBand>
      </targetBands>
      <variables/>
    </parameters>
  </node>
</graph>

In [ ]: