Factorio Forums

When in the map-mode and not moving, the map calculates the amount of resources in your sight (and maybe adding that of the radars later?). A "scanning"-animation can show the scan and after max. 5 secs the resources (trees, coal, stone...) are shown, as simple list in the right edge. This number can also be displayed in the mini-map (turn on/off with shift-m).
Eventually the number of items are also shown (Ctrl-m). Eventually the number of ground tiles also (water, sand...).

This is the geologist-mode.