Creating an empty raster

Creating an empty raster.

This uses the raster package. To create a new raster there are a few parameters that are essential: - The number of cells (as specified by the number of rows and columns) – remember that rasters are square even if the image stored in them is not. - projection (crs) - resolution – in the first example I do not specify a resolution as it is implicit from the information provided. - extent

This example uses a raster layer I have for the Aleza Lake Research Forest as a template.

library(raster)

r <- raster(nrows = 5220, ## number of rows and columns
            ncols = 6100,
            crs   = "+proj=utm +zone=10 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs",
            xmn   = 552600,
            xmx   = 567850,
            ymn   = 5983800,
            ymx   = 5996850 
            )

res(r) ## [1] 2.5 2.5

However, typing in all those numbers is a pain. This is how to do the same thing programatically – based on the raster we just created. In this case I want a different resolution. Below I set the resolution to 10m². Note that the crs command assigns the projection – it does not transform the data.

r2 <- raster(extent(r))  ## create new raster based on extent of first
crs(r2) <- crs(r)        ## assign the crs based on the extent of first 
# crs(r2) <- crs("+init=EPSG:26910")  ## assign crs based on epsg code
res(r2) <- 10