The last part of your question is easy to answer. Before you start processing personal information, you need to ask the affected persons for consent. So now you

The last part of your question is easy to answer. Before you start processing personal information, you need to ask the affected persons for consent. So now you know how to identify them. If you want to get away without consent, you need to design your system in such a way that it doesn't hold personal information. E.g., maybe randomize the raw tracking data as first processing step, and only keep the randomized version.