BandMaths¶

In [1]:

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

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')

band_maths = Operator('BandMaths')

In [3]:

band_maths.describe()

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')

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

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])

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')

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')

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

In [9]:

g.view()

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 [ ]: