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Exercise 5b: Extract shadow and water pixels

In this exercise the following tools will be used:

  • pkinfo: pkascii2ogr, pkextract, pkdumpogr
  • bash: redirection,
  • awk: basic column selection
  • gdal/ogr tools: ogr2ogr

Find geographic coordinates for shadow pixels

cat > ${OUTPUTDIR}/exercise5/shadows.txt <<EOF
shadow 3220825 3124100
shadow 3221025 3124150
shadow 3222325 3123950
shadow 3223750 3124650

Create vector files

pkascii2ogr -i ${OUTPUTDIR}/exercise5/shadows.txt -x 1 -y 2 -n label --ot String -a_srs epsg:3035 -o ${OUTPUTDIR}/exercise5/shadows.shp

Extract LANDSAT shadow pixels

pkextract -i ${LANDSATDIR}/${LANDSATIMG} -s ${OUTPUTDIR}/exercise5/shadows.shp -o ${OUTPUTDIR}/exercise5/shadows_landsat.shp

Calculate mean and stdev shadow pixels

pkstatogr -i ${OUTPUTDIR}/exercise5/shadows_landsat.shp -n B0 -n B1 -n B2 -n B3 -n B4 -n B5 -n B6 -n B7 -mean -stdev| awk '{print $4,$6}' > ${OUTPUTDIR}/exercise5/shadows_landsat_mean_stdev.txt

Dump ogr to ascii text file

pkdumpogr -i ${OUTPUTDIR}/exercise5/shadows_landsat.shp -n label -n B0 -n B1 -n B2 -n B3 -n B4 -n B5 -n B6 -n B7 > ${OUTPUTDIR}/exercise5/shadows_landsat.txt

Extract LANDSAT water profiles from vector cornwallwater.shp and reproject to epsg:3035_ <code bash> ogr2ogr -tsrs epsg:3035 -where “NATURAL='water'” ${OUTPUTDIR}/exercise5/cornwallwater3035.shp ${VECTORDIR}/cornwallwater.shp </code> <code bash> pkextract -i ${LANDSATDIR}/${LANDSATIMG} -s ${OUTPUTDIR}/exercise5/cornwallwater3035.shp -o ${OUTPUTDIR}/exercise5/waterlandsat.shp -r 1 -l -t -10 </code> Dump shape content to ASCII file <code bash> pkdumpogr -i ${OUTPUTDIR}/exercise5/waterlandsat.shp -n B0 -n B1 -n B2 -n B3 -n B4 -n B5 -n B6 -n B7 |awk '{print $2,$3,$4,$5,$6,$7,$8,$9}' > ${OUTPUTDIR}/exercise5/water_landsat.txt </code>
Plot profiles in gnuplot (click here for code)

wiki/exercise5b.txt · Last modified: 2021/01/20 20:36 (external edit)