added ws202425 courses

2024-11-14 13:11:04 +01:00
parent 800282c2e8
commit beb31897b1
461 changed files with 20368 additions and 0 deletions
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+#Preprocessed data import
+l5_2011_rawdn <- stack('L5_2011.tif')
+l5_2011_toa <- stack('L5_2011_TOA.tif')
+l5_2011_surfref <- stack('L5_2011_sr.tif')
+
+#Rescale data according to metadata
+l5_2011_surfref <- -0.2 + l5_2011_surfref*2.75e-05
+
+#Export raster
+writeRaster(l5_2011_surfref, 'L5_2011_sr_rescaled.tif', Format='GTiff', overwrite= TRUE)
+
+#Remove negative values, set negative to 0, above 1 values to 1
+l5_2011_surfref <- reclassify(l5_2011_surfref, c(-Inf,0,0,1,Inf,1))
+
+#Plot
+plotRGB(l5_2011_rawdn, 3,2,1, stretch='lin')
+plotRGB(l5_2011_toa, 3,2,1, stretch='lin')
+plotRGB(l5_2011_surfref, 3,2,1, stretch='lin')
+
+#
+lambda <- c(480, 560, 655, 865, 1610, 2150)
+
+#Pick a spot with vegetation and show the spectra
+plotRGB(l5_2011_surfref, r=4, g=3, b=2, stretch="lin")
+pxy<-locator(1) # This function requires an input! -> Click once in the image on a vegetated area --> then wait!
+
+spectrum_rawdn<-extract(l5_2011_rawdn, cbind(pxy$x[1], pxy$y[1]))
+spectrum_toa<-extract(l5_2011_toa, cbind(pxy$x[1], pxy$y[1]))
+spectrum_surfref<-extract(l5_2011_surfref, cbind(pxy$x[1], pxy$y[1]))
+dev.off()
+
+par(mfrow=c(1,3))
+plot(lambda, spectrum_rawdn, 
+     ylab="raw DN",
+     xlab="wavelength (nm)", type='b')
+plot(lambda, spectrum_toa, 
+     ylab="ToA reflectance",
+     xlab="wavelength (nm)", type='b')
+plot(lambda, spectrum_surfref, 
+     ylab="Surface reflectance",
+     xlab="wavelength (nm)", type='b')
+
+#Load terrain correction file
+dem <- stack('/Users/huaqo/Downloads/SRTM_ffB01_p045r032.tif')
+
+#Match to images
+dem <- resample(dem, l5_2011_surfref)
+
+#Calculate slope and aspect
+slp <- terrain (dem, opt='slope')
+asp <- terrain (dem, opt='aspect')
+
+#Input sun position
+theta_e <- 49.6590900
+theta_a <- 144.56665673
+
+#Calculate the hillshade 
+hs2011 <- hillShade(slp,asp, angle = theta_e, direction = theta_a)
+
+#Plot hillshade
+plot(hs2011, col=grey.colors(255), zlim=c(0,1))
+summary(hs2011)
+
+#Reclassify data
+hs2011 <- reclassify(hs2011, matrix(c(-Inf, 0, 0.0), 1, 3))
+
+#Topographic normalization with hillshade
+l5_2011_topo <- l5_2011_surfref*cos((90-theta_e)/180*pi) / hs2011
+
+#Export
+writeRaster(l5_2011_topo, 'l5_2011_topo.tif', format='GTiff', overwrite=TRUE)
+
+#Plot
+par(mfrow=c(1,2))
+plotRGB(l5_2011_surfref, r=4, g=3, b=2, stretch="lin")
+plotRGB(l5_2011_topo, r=4, g=3, b=2, stretch="lin")
+
+#Export Plot
+savePlot('topographic correction', type='jpeg')
+
+#Read shapefile with two example points
+points <- readOGR('/Users/huaqo/Downloads/shape/points.shp')
+
+#Plot points
+plotRGB(l5_2011_surfref,4,3,2, stretch='lin')
+plot(points, col=c('green', 'orange'), pch=19, add=TRUE)
+
+#Extract pixel values below points
+spectrum_surfref <- extract(l5_2011_surfref, points)
+spectrum_topo <- extract(l5_2011_topo, points)
+
+spectrum_surfref
+spectrum_topo
+
+#Plot spectra
+x11()
+par(mfrow=c(2,2))
+plot(lambda, spectrum_surfref[2,], 
+     ylab="Surface reflectance",
+     xlab="wavelength (nm)", type='b', ylim=c(0,0.4), main="no topo - illuminated")
+plot(lambda, spectrum_surfref[1,], 
+     ylab="Surface reflectance",
+     xlab="wavelength (nm)", type='b', ylim=c(0,0.4), main="no topo - shaded")
+plot(lambda,spectrum_topo[2,], 
+     ylab="Surface reflectance",
+     xlab="wavelength (nm)", type='b', ylim=c(0,0.4), main="topo - illuminated")
+plot(lambda,spectrum_topo[1,], 
+     ylab="Surface reflectance",
+     xlab="wavelength (nm)", type='b', ylim=c(0,0.4), main="topo - shaded")