Hi users of raster: When a point lands within a raster cell, the cell is correctly identified. But when a point lands on the border between two adjacent raster cells, cell identity seems to be inconsistent. We are wondering if this is an error? Example code follows to demonstrate our question: require(raster) xmn=-62 ymn=40 xmx=-60 ymx=42 res=.1 # simple raster with integers fill r0 <- raster( xmn=xmn, ymn=ymn, xmx=xmx, ymx=ymx, res=res ) r0[] <- 1:ncell(r0) # choose points along a horizontal band: locx = seq(xmn, xmx, res) xy1 <- cbind( locx + res/2, rep(ymn+res+res/2, dim(r)[1] ) ) # center of a raster cell xy2 <- cbind( locx, rep(ymn+res+res/2, dim(r)[1] ) ) # on x-boundary xy3 <- cbind( locx + res/2, rep(ymn+res, dim(r)[1] ) ) # on y-boundary xy4 <- cbind( locx, rep(ymn+res, dim(r)[1] ) ) # on a corner # plots to visualize selected points cid1 = cellFromXY(r, xy1); r = r0; r[cid1] <- NA; plot(r) cid2 = cellFromXY(r, xy2); r = r0; r[cid2] <- NA; plot(r) cid3 = cellFromXY(r, xy3); r = r0; r[cid3] <- NA; plot(r) cid4 = cellFromXY(r, xy4); r = r0; r[cid4] <- NA; plot(r) The expectation would have been to see no banding as seen in xy1 and xy3. But xy2 and xy4 seem to skip a few cells. Not sure why? Thanks! [[alternative HTML version deleted]]