Those ledges indicate a higher elevation that is non accessible-accessible from roundground troops minusexcept for the ramp used. ThisThis is some whatsomewhat a good strategy for parking Siege Tanks with the Siege ability upgraded from the Factory Add-on. It also effects the distance used in calculating when any ground unit can stop and fire at the enemy above.
The Gameplaygameplay is not affected when air units are considered. both, both because they fly and range on attack is measured differently thenthan when ground units attack.
As for telling what is where, the ledges that define the no ground access. Gamewise Game-wise, there is no affected anything past the width of the ramp. The wider the ramp the more issues youllyou'll have stopping groundsground units from coming in. the The thinner ramps bottle neckbottleneck units and make siege tanks and other bunkers options (e.g. bunkers) a lot easier to defendbetter in defending camps and HQ bases.