Direction

This section describes how the direction of movement is determined.

At each simulation step, a person’s movement direction is chosen in two stages:

1. Identification of possible movement directions.
2. Selection of one direction** in which the person will move.

Determining Possible Movement Directions

This process is carried out during the evacuation situation analysis for each individual and consists of the following sub-steps:

1. Several potential directions in which the person can move are selected.

2. For each direction, the following are determined: the distance to the nearest visible person, the distance to the nearest visible obstacle, and the shortest direction to the current boundary.

3. For each direction, four dimensionless factors are calculated, representing:

   1. How much this direction deviates from the shortest path to the exit.
   2. How much this direction deviates from the person’s current direction of movement.
   3. How close other people are in this direction.
   4. How close obstacles are in this direction.

4. For each direction, a probability is calculated that the person will choose this direction—defined as the product of all four factors.

5. If necessary, each direction is adjusted to avoid collisions with obstacles.

6. For each direction, the destination point is calculated — where the person would end up if they moved in that direction.

It should be noted that at this stage, potential collisions with other people are not checked.

Selecting a Single Direction of Movement

This process is carried out during the people movement stage and consists of the following sub-steps:

1. The direction with the highest probability is selected.
2. The selected direction is checked for collisions with people and obstacles.
3. If no collisions are detected, the person moves in the chosen direction. Otherwise, the next untested direction with the highest remaining probability is selected.
4. If no direction can be selected (i.e., all directions would result in collisions with people or obstacles), the person remains in place and rotates to face the direction with the highest probability.