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wiki:exercise10

Exercise 10: Create yearly MODIS composite

In this exercise the following tools will be used:

  • pktools: pkmosaic
  • bash: for loop, echo

Create a directory for this exercise

mkdir ${OUTPUTDIR}/exercise10

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: -min 2) and use a compositing rule that selects the maximum NDVI value (composit rule: -cr maxndvi).

look at the help information how to use pkmosaic

pkmosaic -h
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
Do not forget that pktools start counting from 0
pkmosaic $(for file in ${MODIS500DIR}/2010*-MODIS500_CW.tif;do echo " -i " $file;done) -o ${OUTPUTDIR}/exercise10/2010-MODIS500_CW.tif --rband 0 --rband 1 -cr maxndvi --validBand 7 -min 2 -nodata 0
wiki/exercise10.txt · Last modified: 2017/12/05 22:53 (external edit)