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# R code to plot latitudinal profiles of (circular) mean aspect, along
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# with both RMSE and (circular) correlation coefficients comparing fused
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# layers with both the raw ASTER and with the Canada DEM
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#
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# Aspect layers were generated from the respect DEMs in this way:
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# $ gdaldem aspect -s 111120 <layer>.tif <layer>_a.tif
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# ...where the default azimuthal behavior produces output values ranging
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# from 0-360 where 0 is north, and proceeding clockwise
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#
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# For exploratory plotting, note the following (uses 'circular'
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# package):
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# > cx <- circular(as.matrix(a.bg)[151,], units="degrees",
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# rotation="clock", zero=pi/2)
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# > rose.diag(cx, bins=8)
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# > points(mean.circular(cx, na.rm=TRUE), col="red")
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#
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#
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# The results (plots) are saved at
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# "/data/project/organisms/DEM?Yuni/documents/aspect"
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#
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# Original author: Jim Regetz
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# [13-JUL-2011]
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# Edits by Yuina to auto-apply for nine regions.
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#
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# 9-Dec-2011
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# Yuina Nunokawa
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library(raster)
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library(circular)
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# load aspecct rasters
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aster.dir <- "/data/project/organisms/DEM/Yuni/Data/aster2"
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srtm.dir <- "/data/project/organisms/DEM/Yuni/Data/srtm"
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aster.straddle <- list.files(aster.dir, pattern="^aster2.*_straddle_a.tif")
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srtm.below <- list.files(srtm.dir, pattern="^srtm_.*_below_a.tif")
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fused.straddle <- list.files(aster.dir, pattern="^fused.*_straddle_a.tif")
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fused.bgau <- list.files(aster.dir, pattern="^fused.*_blendgau_a.tif")
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# simple helper function to calculate row-wise means using circular
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# mean, patterned after circ.mean in the CircStats package
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rowMeansC <- function(r1, na.rm=TRUE) {
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m1 <- as.matrix(r1)
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m1[] <- (m1 * pi)/180
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sinr <- rowSums(sin(m1), na.rm=na.rm)
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cosr <- rowSums(cos(m1), na.rm=na.rm)
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cmeans <- atan2(sinr, cosr)
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(cmeans * 180)/pi
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}
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aspect <- function(a.aster2, a.srtm, a.uncor, a.bg, file.name, aster.dir, srtm.dir){
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# extract raster latitudes for later
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lats2400 <- yFromRow(a.aster2, 1:nrow(a.aster2))
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lats1200 <- yFromRow(a.srtm, 1:nrow(a.srtm))
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# initialize output pdf device driver
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name <- paste("aspect_", file.name, ".pdf", sep="")
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pdf(file.path("/data/project/organisms/DEM/Yuni/documents/aspect", file=name), height=8, width=11.5)
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#
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# plot latitudinal profiles of mean aspect
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#
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par(mfrow=c(2,2), omi=c(1,1,1,1))
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ylim <- c(-180, 180)
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plot(lats2400, rowMeansC(a.aster2), type="l", xlab="Latitude", ylab="Mean aspect", ylim=ylim)
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axis(2, at=c(-180, -90, 0, 90, 180), labels=c("S", "W", "N", "E", "S"))
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lines(lats1200, rowMeans(as.matrix(a.srtm), na.rm=TRUE), col="red")
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text(min(lats2400), max(ylim)+0.5, pos=4, font=3, labels="Original")
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legend("topright", legend=c("ASTER2", "SRTM"), col=c("blue", "red"), lty=c(1, 1), bty="n")
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abline(v=60, col="red", lty=2)
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mtext(expression(paste("Latitudinal profiles of mean aspect", file.name)), adj=0, line=2, font=2)
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plot(lats2400, rowMeansC(a.uncor), type="l", xlab="Latitude", ylab="Mean aspect", ylim=ylim)
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axis(2, at=c(-180, -90, 0, 90, 180), labels=c("S", "W", "N", "E", "S"))
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legend("topright", legend=c("ASTER2"), col=c("black"), lty=c(1, 1), bty="n")
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text(min(lats2400), max(ylim)+0.5, pos=4, font=3, labels="simple fused")
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abline(v=60, col="red", lty=2)
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plot(lats2400, rowMeansC(a.bg), type="l", xlab="Latitude", ylab="Mean aspect", ylim=ylim)
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legend("topright", legend=c("ASTER2"), col=c("black"), lty=c(1, 1), bty="n")
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text(min(lats2400), max(ylim)+0.5, pos=4, font=3, labels="gaussian blend")
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abline(v=60, col="red", lty=2)
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dev.off ()
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}
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num.regions <- 9
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plotAspect <-lapply(1:num.regions, function(region, aster.dir, srtm.dir){
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a.aster2 <- raster(file.path(aster.dir, aster.straddle[region]))
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a.srtm <- raster(file.path(srtm.dir, srtm.below[region]))
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a.uncor <- raster(file.path(aster.dir, fused.straddle[region]))
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a.bg <- raster(file.path(aster.dir, fused.bgau[region]))
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file.name <- substr(srtm.below[region], 6, 13)
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aspect(a.aster2, a.srtm, a.uncor, a.bg, file.name, aster.dir, srtm.dir)
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}, aster.dir=aster.dir, srtm.dir=srtm.dir)
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