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wiki:exercise8 [2017/12/05 22:53]
wiki:exercise8 [2020/07/17 06:39] (current)
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 +====== Exercise 8: Create yearly MODIS composite ======
 +In this exercise the following tools will be used:
 +  * pktools: pkmosaic
 +  * bash: for loop, echo
 +In this exercise we will learn how to create a maximum value composit image when a number of images are available with overlap.
 +The MODIS images at 500 m have 7 spectral bands and an additional two bands for the cloud mask and a count value. ​
 +The cloud mask is defined as: 0 (most likely cloudy), 1 (probably cloudy), 2 (probably cloud free) and 3 (most likely cloud free).
 +The count value represents the number of valid images that were used for the composit. see how to create a yearly MODIS composite at 500 m for 2010.
 +Select cloud free pixels only (cloud value > 2) and use a compositing rule that selects the maximum NDVI value (rule=1).
 +__look at the help information how to use pkmosaic__
 +<code bash>
 +pkmosaic -h
 +<note tip>
 +The MODIS bands at 500 m:\\
 +band 1: red\\
 +band 2: nir\\
 +band 3: blue\\
 +band 4: green\\
 +band 5: nir\\
 +band 6: swir\\
 +band 7: mir\\
 +band 8: cloud mask (3 is cloud free)\\
 +band 9: number of days used for monthly composit\\
 +<note warning>​Do not forget that pktools start counting from 0</​note>​
 +<code bash>
 +pkmosaic $(for file in ${MODIS500DIR}/​2010*-MODIS500_CW.tif;​do echo " -i " $file;done) -o ${OUTPUTDIR}/​2010-MODIS500_CW.tif --rband 0 --rband 1 -m 1 --validBand 7 -min 2