To plan or not to plan : lessons learned from building large scale social simulations

Building large scale social simulations in virtual environments requires having a large number of virtual agents. Often we need to simulate hundreds or even thousands of individuals in order to have a realistic and believable simulation. One of the obvious desires of the developers of such simulations is to have a high degree of automation in regards to agent behaviour. The key techniques to provide this automation are: crowd simulation, planning and utility based approaches. Crowd simulation algorithms are appropriate for simulating simple pedestrian movement or for showing group activities, which do not require complex object use, but are not suitable for simulating complex everyday life, where agents need to eat, sleep, work, etc. Planning and utility based approaches remain the most suitable for this situation. In our research we are interested in developing advanced history and cultural heritage simulations and have tried to utilise planning and utility based methods (the most popular one of which is used in the game “The Sims”). Here we examine pros and cons of each of the two techniques and illustrate the key lessons that we have learned with a case study focused on developing a simulation of everyday life in ancient Mesopotamia 5000 B.C