Best multi-objective 3D path optimization algorithm?

Question

I would like to calculate 3D balanced paths to building exits at once, for huge amount of people (2000). Since the problem is related to evacuation and solutions for 3D paths (the fastest and others) can be precalcualted and I am going to store 3D paths in database to accelerate the process. As I see it, there are two solutions so far:

1. Calculation of a number of passing through nodes, in graph environment representation, but probably the time calculation will be intolerable.
2. Using GA. However, I cannot find a good described optimization example, where is used genetic algorithm.

Can you tell me a way of using GA for multiobjective optimization, because I found only implementation of GA for finding shortest path? and Which algorithm is the best for multi-object optimization?

Answer 1

Genetic Algorithm as it is cannot be easily used for multi-objective optimisation directly. If you want to use the purest GA you have to combine the objectives into a single objective, e.g. by summing weighted values of each objective. But this often does not work very well, especially when there is a strong tradeoff between the objectives.

However, there are genetic (evolutionary) algorithms designed specifically for multi-objective optimisation. Probably the most famous one and one of the best is the NSGA-II which stands for Nondominated Sorting Genetic Algorithm II. It's also relatively easy to implement (I did once). But there other MOEAs (Multi-Objective Evolutionary Algorithm) too, just google it. Some of them also use the nondomination idea, others not.