```r
# or using mapview
# proj4string(twi) = paste0("+proj=utm +zone=17 +south +ellps=WGS84 +towgs84=", 
#                           "0,0,0,0,0,0,0 +units=m +no_defs")
# mapview(twi, col.regions = RColorBrewer::brewer.pal(n = 9, "Blues"), 
#         at = seq(cellStats(twi, "min") - 0.01, cellStats(twi, "max") + 0.01, 
#                  length.out = 9))
```