Zombie Skills/Scent Death
From The Urban Dead Wiki
When a zombie or survivor with this skill sees a pile of bodies, they can tell how many of them are in the process of revivifying. They get a message like "There are x dead bodies here. y of them smell strange", where x is the number of bodies in total and y is the number of revivifying bodies. "Scent Death" also is an action that can be used by the zombie for 1 AP to view a "map" that indicates how many dead bodies and zombies are in the surrounding 5 block radius, plus directions to the nearest grouping of members of the zombie's own group, if any such exists. The map looks as shown at the right. It seems that zombies show up as progressively brighter values of green (more zombies) and dead bodies as brighter values of red (more bodies). When green and red mix, you get various shades of brown, orange, yellow, or lime, indicating squares with both zombies and dead bodies (as most often seen in a siege, or anywhere zombies are being killed / revived). Notably, the ability to tell if a body is revivifying using Scent Death is the only Zombie skill which continues to function even while that character is still alive.
Current analysis indicates that the rgb color code of the cells in the table that compose the scent death map have numeric values that increase as the numbers of dead bodies or zombies in those blocks increase. Dead bodies add to the Red value, and zombies add to the Green value. It is uncertain what the exact correspondence is, but it does not seem to be a direct ratio; random noise is included, and it's possible that bodies / zombies that are inside buildings count differently than those that are outside.