Hi,
i’m making a simulation that uses a grid. So far I have implemented path finding, taking into consideration only terrain. I need to be able to take into account other objects such as the characters however (problem is they arent necessarily in the same place they were when i check). Do I need to create masks for my characters? or is there an easier way of doing it because I am using a grid? Thanks for any help. 
if you’re worried about how long it would take to calculate the unit’s path often enough for it to go around a moving object, you could do it in 2 stages. (this being just imho)
first calculate the terrain waypoints for the journey, then do a calculation every second or so between the units current location and the next waypoint.
0.5 - 1 second is probably short enough… the warcaft peons sometimes paused while walking if there was a lot of them trying to make their way to and from the gold mines.