Abstract: As an effective tool,density field provides an intuitive and efficient means to quickly adjust the direction of pedestrians’ movement in crowd simulation when pedestrians need to percept the density information around.Social force model(SFM) is a popular and classical method in the research of crowd simulation and its significance lies in the simulation of some common-seen self-organized phenomenon.However,social force model still has many deficiencies.For instance,the time complexity of social force model grows exponentially when the number of pedestrians increases,and others are pedestrians’ overlapping and oscillating.This paper modified social force model using density field.First,pedestrians’ stress region and walls’ repulsive distance were introduced to reduce time complexity of the algorithm.Se-condly,this paper built a grid density field matching social force model(SFM),so that pedestrian can bypass the high density region.At last,we proposed a concept named density guiding threshold(DGT).When the grid density is bigger than DGT,pedestrian chooses a new direction which combines the goal direction and the direction of low density region.The numerous experimental results show that short-range SFM using density field not only simulates basic self-organi-zed phenomenon of crowd,but also has advantages in time complexity.

Key words: Crowd simulation,Social force model,Crowd density,Density field,Density guiding thresholdi