I have a problem with autoKrig function and I try to make a reproducible example here:
library(automap)
library(raster)
library(dismo)
bio <- getData("worldclim", var="bio", res=10)
bio1 <- raster(bio, layer=1)
bio12 <- raster(bio, layer=12)
predictors <- stack(bio1, bio12)
bg <- randomPoints(bio1, 50)
data <- extract(predictors, bg)
data <- cbind(bg,data)
data <- data.frame(data)
coordinates(data)=~x+y
proj4string(data) = CRS("+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0")
kg <- autoKrige(bio1~bio12, data, new_data=predictors)
This will result in:
Error in autoKrige(bio1 ~ bio12, data, new_data = predictors) :
Either input_data or new_data is in LongLat, please reproject.
input_data: +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
new_data: +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
I get the same error with my original data. I appreciate any help.
If you read the help file, it will tell you why it is throwing that error.
autoKrige performs some checks on the coordinate systems of input_data and new_data. If one or both is NA, it is assigned the projection of the other. If they have different projections, an error is raised. If one or both has a non-projected system (i.e. latitude-longitude), an error is raised. This error is raised because 'gstat does use spherical distances when data are in geographical coordinates, however the usual variogram models are typically not non-negative definite on the sphere, and no appropriate models are available' (Edzer Pebesma on r-sig-geo).
It looks like you need to project your data before calling autoKrige.