rasters2Cor {lidaRtRee}

Correlation between two rasters

Description

computes correlation between two rasters, based on the extent of the smallest one.

Usage

rasters2Cor(raster_b, raster_s, mask = NULL, small.SC = TRUE)

Arguments

raster_b

SpatRaster. raster to correlate with largest extent

raster_s

SpatRaster. raster to correlate with smallest extent

mask

SpatRaster. mask of area to correlate

small.SC

boolean. is the small raster already standardized and centered ?

Value

A numeric

See Also

rasters_moving_cor to compute correlation between rasters for different translations

Examples

# create raster
r_b <- terra::rast(xmin = 0, xmax = 40, ymin =0 , ymax = 40,
resolution = 1, crs = NA)
xy <- terra::xyFromCell(r_b, 1:(nrow(r_b) * ncol(r_b)))

# add Gaussian surface and noise
z <- 3 * exp(-((xy[, 1] - 20)^2 + (xy[, 2] - 20)^2 / 2) / 6)
r_b <- terra::rast(cbind(xy, z), type = "xyz")

# create circular mask of radius 5
z_mask <- (xy[, 1] - 20)^2 + (xy[, 2] - 20)^2 < 5^2
r_mask <- terra::rast(cbind(xy, z_mask), type = "xyz")

# create small raster of size 20
r_s <- terra::crop(r_b, terra::ext(c(10, 30, 10, 30)))

# add noise to small raster
terra::values(r_s) <- terra::values(r_s) + rnorm(ncol(r_s) * nrow(r_s), 0, 0.5)
r_mask <- terra::crop(r_mask, terra::ext(c(10, 30, 10, 30)))

# compute correlation on masked area where signal to noise ratio is lower
rasters2Cor(r_b, r_s, r_mask, small.SC = FALSE)

# compute correlation for whole small raster
rasters2Cor(r_b, r_s, small.SC = FALSE)

# display large raster
terra::plot(r_b, main = "Large raster")
# display small raster
terra::plot(r_s, main = "Small raster")
# display mask
terra::plot(r_mask, main = "Computation mask")