# R code to plot latitudinal profiles of mean aspect, along with both

# RMSE and correlation coefficients comparing fused layers with both the

# raw ASTER and with the Canada DEM

#

# Jim Regetz

# NCEAS

# Created on 08-Jun-2011

library(raster)

datadir <- "/home/regetz/media/temp/terrain/aspect"

# load aspect rasters

a.aster <- raster(file.path(datadir, "aster_300straddle_a.tif"))

a.srtm <- raster(file.path(datadir, "srtm_150below_a.tif"))

a.uncor <- raster(file.path(datadir, "fused_300straddle_a.tif"))

a.enblend <- raster(file.path(datadir, "fused_300straddle_enblend_a.tif"))

a.bg <- raster(file.path(datadir, "fused_300straddle_blendgau_a.tif"))

a.can <- raster(file.path(datadir, "cdem_300straddle_a.tif"))

# extract raster latitudes for later

lats300 <- yFromRow(a.aster, 1:nrow(a.aster))

lats150 <- yFromRow(a.srtm, 1:nrow(a.srtm))

# initialize output pdf device driver

pdf("aspect-assessment.pdf", height=8, width=11.5)

#

# plot latitudinal profiles of mean aspect

#

par(mfrow=c(2,2), omi=c(1,1,1,1))

ylim <- c(160, 180)

plot(lats300, rowMeans(as.matrix(a.can), na.rm=TRUE), type="l",

    xlab="Latitude", ylab="Mean aspect", ylim=ylim)

text(min(lats300), min(ylim)+0.5, pos=4, font=3, labels="Original DEMs")

lines(lats300, rowMeans(as.matrix(a.aster), na.rm=TRUE), col="blue")

lines(lats150, rowMeans(as.matrix(a.srtm), na.rm=TRUE), col="red")

legend("bottomright", legend=c("ASTER", "SRTM", "CDED"), col=c("blue",

    "red", "black"), lty=c(1, 1), bty="n")

abline(v=60, col="red", lty=2)

mtext(expression(paste("Latitudinal profiles of mean aspect (",

    136*degree, "W to ", 96*degree, "W)")), adj=0, line=2, font=2)

plot(lats300, rowMeans(as.matrix(a.uncor), na.rm=TRUE), type="l",

    xlab="Latitude", ylab="Mean aspect", ylim=ylim)

text(min(lats300), min(ylim)+0.5, pos=4, font=3, labels="simple fused")

abline(v=60, col="red", lty=2)

plot(lats300, rowMeans(as.matrix(a.enblend), na.rm=TRUE), type="l",

    xlab="Latitude", ylab="Mean aspect", ylim=ylim)

text(min(lats300), min(ylim)+0.5, pos=4, font=3, labels="multires spline")

abline(v=60, col="red", lty=2)

plot(lats300, rowMeans(as.matrix(a.bg), na.rm=TRUE), type="l",

    xlab="Latitude", ylab="Mean aspect", ylim=ylim)

text(min(lats300), min(ylim)+0.5, pos=4, font=3, labels="gaussian blend")

abline(v=60, col="red", lty=2)

#

# plot latitudinal profiles of RMSE

#

# simple helper function to calculate row-wise RMSEs, accounting for the

# fact that aspect values are circular (0-360), so the difference

# between e.g. 5 and 355 should only be 10

rmse <- function(r1, r2, na.rm=TRUE, use) {

    diffs <- abs(as.matrix(r1) - as.matrix(r2))

    if (!missing(use)) diffs[!use] <- NA

    diffs[] <- ifelse(diffs>180, 360-diffs, diffs)

    sqrt(rowMeans(diffs^2, na.rm=na.rm))

}

par(mfrow=c(2,3), omi=c(1,1,1,1))

ylim <- c(0, 100)

# ...with respect to ASTER

plot(lats300, rmse(a.uncor, a.aster), type="l", xlab="Latitude",

    ylab="RMSE", ylim=ylim)

lines(lats150, rmse(crop(a.uncor, extent(a.srtm)), a.srtm), col="blue")

legend("topright", legend=c("ASTER", "SRTM"), col=c("black", "blue"),

    lty=c(1, 1), bty="n")

text(min(lats300), max(ylim)-5, pos=4, font=3, labels="simple fused")

abline(v=60, col="red", lty=2)

mtext(expression(paste(

    "Aspect discrepancies with respect to separate ASTER/SRTM components (",

    136*degree, "W to ", 96*degree, "W)")), adj=0, line=2, font=2)

plot(lats300, rmse(a.enblend, a.aster), type="l", xlab="Latitude",

    ylab="RMSE", ylim=ylim)

lines(lats150, rmse(crop(a.enblend, extent(a.srtm)), a.srtm), col="blue")

legend("topright", legend=c("ASTER", "SRTM"), col=c("black", "blue"),

    lty=c(1, 1), bty="n")

text(min(lats300), max(ylim)-5, pos=4, font=3, labels="multires spline")

abline(v=60, col="red", lty=2)

plot(lats300, rmse(a.bg, a.aster), type="l", xlab="Latitude",

    ylab="RMSE", ylim=ylim)

lines(lats150, rmse(crop(a.bg, extent(a.srtm)), a.srtm), col="blue")

legend("topright", legend=c("ASTER", "SRTM"), col=c("black", "blue"),

    lty=c(1, 1), bty="n")

text(min(lats300), max(ylim)-5, pos=4, font=3, labels="gaussian blend")

abline(v=60, col="red", lty=2)

# ...with respect to CDEM

plot(lats300, rmse(a.uncor, a.can), type="l", xlab="Latitude",

    ylab="RMSE", ylim=ylim)

text(min(lats300), max(ylim)-5, pos=4, font=3, labels="simple fused")

abline(v=60, col="red", lty=2)

mtext(expression(paste(

    "Aspect discrepancies with respect to Canada DEM (",

    136*degree, "W to ", 96*degree, "W)")), adj=0, line=2, font=2)

plot(lats300, rmse(a.enblend, a.can), type="l", xlab="Latitude",

    ylab="RMSE", ylim=ylim)

text(min(lats300), max(ylim)-5, pos=4, font=3, labels="multires spline")

abline(v=60, col="red", lty=2)

plot(lats300, rmse(a.bg, a.can), type="l", xlab="Latitude",

    ylab="RMSE", ylim=ylim)

text(min(lats300), max(ylim)-5, pos=4, font=3, labels="gaussian blend")

abline(v=60, col="red", lty=2)

# close pdf device driver

dev.off()

stop("not doing correlations")

#

# plot latitudinal profiles of correlation coefficients

#

# simple helper function to calculate row-wise correlation coefficients

corByLat <- function(r1, r2, rows) {

    if (missing(rows)) {

        rows <- 1:nrow(r1)

    }

    m1 <- as.matrix(r1)

    m2 <- as.matrix(r2)

    sapply(rows, function(row) cor(m1[row,], m2[row,],

        use="pairwise.complete.obs"))

}

par(mfrow=c(2,3), omi=c(1,1,1,1))

ylim <- c(0, 1)

# ...with respect to ASTER

plot(lats300, corByLat(a.uncor, a.aster), type="l", xlab="Latitude",

    ylab="Correlation", ylim=ylim)

lines(lats150, corByLat(crop(a.uncor, extent(a.srtm)), a.srtm), col="blue")

legend("bottomright", legend=c("ASTER", "SRTM"), col=c("black", "blue"),

    lty=c(1, 1), bty="n")

text(min(lats300), min(ylim), pos=4, font=3, labels="simple fused")

abline(v=60, col="red", lty=2)

mtext(expression(paste(

    "Aspect correlations with respect to separate ASTER/SRTM components (",

    136*degree, "W to ", 96*degree, "W)")), adj=0, line=2, font=2)

plot(lats300, corByLat(a.enblend, a.aster), type="l", xlab="Latitude",

    ylab="Correlation", ylim=ylim)

lines(lats150, corByLat(crop(a.enblend, extent(a.srtm)), a.srtm), col="blue")

legend("bottomright", legend=c("ASTER", "SRTM"), col=c("black", "blue"),

    lty=c(1, 1), bty="n")

text(min(lats300), min(ylim), pos=4, font=3, labels="multires spline")

abline(v=60, col="red", lty=2)

plot(lats300, corByLat(a.bg, a.aster), type="l", xlab="Latitude",

    ylab="Correlation", ylim=ylim)

lines(lats150, corByLat(crop(a.bg, extent(a.srtm)), a.srtm), col="blue")

legend("bottomright", legend=c("ASTER", "SRTM"), col=c("black", "blue"),

    lty=c(1, 1), bty="n")

text(min(lats300), min(ylim), pos=4, font=3, labels="gaussian blend")

abline(v=60, col="red", lty=2)

# ...with respect to CDEM

plot(lats300, corByLat(a.uncor, a.can), type="l", xlab="Latitude",

    ylab="Correlation", ylim=ylim)

text(min(lats300), min(ylim), pos=4, font=3, labels="simple fused")

abline(v=60, col="red", lty=2)

mtext(expression(paste(

    "Aspect correlations with respect to Canada DEM (",

    136*degree, "W to ", 96*degree, "W)")), adj=0, line=2, font=2)

plot(lats300, corByLat(a.enblend, a.can), type="l", xlab="Latitude",

    ylab="Correlation", ylim=ylim)

text(min(lats300), min(ylim), pos=4, font=3, labels="multires spline")

abline(v=60, col="red", lty=2)

plot(lats300, corByLat(a.bg, a.can), type="l", xlab="Latitude",

    ylab="Correlation", ylim=ylim)

text(min(lats300), min(ylim), pos=4, font=3, labels="gaussian blend")

abline(v=60, col="red", lty=2)