## ---- echo=FALSE--------------------------------------------------------------
knitr::include_graphics("img/sphere.png")


## ---- crs1--------------------------------------------------------------------
library(terra)
f <- system.file("ex/lux.shp", package="terra")
p <- vect(f)
p


## -----------------------------------------------------------------------------
crs(p)


## -----------------------------------------------------------------------------
pp <- p
crs(pp) <- ""
crs(pp)
crs(pp) <- "+proj=longlat +datum=WGS84"
crs(pp)


## -----------------------------------------------------------------------------
newcrs <- "+proj=robin +datum=WGS84"


## -----------------------------------------------------------------------------
rob <- terra::project(p, newcrs)
rob


## -----------------------------------------------------------------------------
p2 <- terra::project(rob, "+proj=longlat +datum=WGS84")


## ---- prj1--------------------------------------------------------------------
r <- rast(xmin=-110, xmax=-90, ymin=40, ymax=60, ncols=40, nrows=40)
values(r) <- 1:ncell(r)
r
plot(r)


## -----------------------------------------------------------------------------
newcrs
pr1 <- terra::project(r, newcrs)
crs(pr1)
plot(pr1)


## -----------------------------------------------------------------------------
x <- rast(pr1)
# Set the cell size 
res(x) <- 200000


## ---- prj3--------------------------------------------------------------------
pr3 <- terra::project(r, x)
pr3
plot(pr3)