good general example

[mdsumner]

Take raw arrays from ROMS, map them as raster "index grids" and regrid with interpolation (or lookup any points).
salt_200.zip

salt<-"salt_200.mat"
library(rmatio)
s <- rmatio::read.mat(salt)

library(quadmesh)
library(raster)
cd <- t(flip(brick(raster(s$lon), raster(s$lat)), "x"))
cd <- setExtent(cd, extent(0, ncol(cd), 0, nrow(cd)))
saltraster <- flip(raster(t(s$salt_200)), "y")
saltraster <- setExtent(saltraster, extent(0, ncol(saltraster), 0, nrow(saltraster)))
mesh_plot(saltraster, coords = cd, crs = "+proj=stere +lat_0=-90 +lon_0=100 +datum=WGS84")

library(angstroms)
r <- raster(extent(77, 95, -66, -55), res = 1, crs = "+proj=longlat +datum=WGS84")

xy <- romsmap(SpatialPointsDataFrame(coordinates(r, sp = TRUE), data.frame(a = 1:ncell(r))), cd)
plot(saltraster)
points(xy, pch = ".")

plot(setValues(r, raster::extract(saltraster, xy), method = "bilinear"))