GPT Cookbook: PixEx


Creates a text based file containing band values for single pixels or aggregate values for a grid of pixels.


Example 1  Matchups to In Situ Cruise Stations








Example 1    Matchups to In Situ Cruise Stations


This uses a data file which contains measurement time and location for an in situ cruise. It then extracts matching pixels (in the form of 5x5 mean aggregate) for an input level-2 file with criteria restrictions of a 3 hour time window and several quality flags.


Command Line Entry

gpt PixExGraph.xml -Pifile=A2010317175500.L2_LAC_OC.nc -p PixEx.par -Phome=$HOME -PoutputFilePrefix=CV5_A2010317175500 -PcoordinatesFile=cruiseCV5_2010317.txt

File = PixExGraph.xml

<graph id="PixExGraph">
  <version>1.0</version>
  <node id="Read">
    <operator>Read</operator>
    <sources/>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
       <file>${ifile}</file>
       <formatName>SeaDAS-L2</formatName>
    </parameters>
  </node>
  <node id="PixEx">
    <operator>PixEx</operator>
    <sources>
      <sourceProduct refid="Read"/>
    </sources>
    <parameters class="com.bc.ceres.binding.dom.XppDomElement">
      <outputDir>${home}/${outputDir}</outputDir>:
      <outputFilePrefix>${outputFilePrefix}</outputFilePrefix>

      <coordinatesFile>${home}/${coordinatesFileDir}/${coordinatesFile}</coordinatesFile>
      <timeDifference>${timeDifference}</timeDifference>

      <exportBands>${exportBands}</exportBands>
      <exportTiePoints>${exportTiePoints}</exportTiePoints>
      <exportMasks>${exportMasks}</exportMasks>

      <windowSize>${windowSize}</windowSize>
      <aggregatorStrategyType>${aggregatorStrategyType}</aggregatorStrategyType>

      <expression>${expression}</expression>

      <exportExpressionResult>false</exportExpressionResult>

    </parameters>

  </node>
</graph>

File = PixEx.par

#home=DEFINED_ON_COMMAND_LINE

outputDir=Desktop/GptExamples/help/PixEx/
#outputFilePrefix=DEFINED_ON_COMMAND_LINE

coordinatesFileDir=Desktop/GptExamples/help/PixEx
#coordinatesFile=DEFINED_ON_COMMAND_LINE

timeDifference=3H

exportBands=true
exportTiePoints=false
exportMasks=false

windowSize=5
aggregatorStrategyType=mean

expression=!(l2_flags.HIGLINT and l2_flags.HISATZEN and l2_flags.STRAYLIGHT)

File = cruiseCV5_2010317.txt*
* The coordinates file must be tab delimited -- exactly one tab and no character spaces between each field.


DateTime	Name	Lat	Lon
2010-11-13T12:03:00	52	40.7537	-70.7162
2010-11-13T14:05:00	53	40.5477	-70.5050
2010-11-13T15:32:00	53B	40.3522	-70.3797
2010-11-13T18:02:00	54	40.0255	-70.1460
2010-11-13T20:00:00	54A	40.2033	-70.0627
2010-11-13T21:18:00	55	40.3577	-69.9882