Part 107 UAS pilot reported while flying a photo shoot for a sports game there were several occasions when persons walked underneath the path of the UAS.

Narrative

sUAS was being operated for the purpose of aerial filming of a football game. A Visual Observer (VO) was used and the sUAS was being operated in near proximity to the field and players; however in all cases the area below the sUAS were constantly being checked to ensure no people were directly beneath the sUAS. This was done both visually by myself (the pilot) and visual observer; but also but continually orienting the camera (providing the live view to the pilot) straight down to check for people. During the course of play however; on several occasions people/players ran toward the area previously cleared; potentially passing directly under the sUAS. Once I realized this was occurring; I modified the flight paths to provide greater clearance from people and avoid repeat occurrences. A contributing factor is that by nature; it is not possible to gauge the distance of the sUAS visually as compared to objects on the ground and the best way to determine whether you are directly over people is to look straight down. Even still; the parallax of the camera can create the illusion of not being directly overhead when you are; and vice versa.The regulation on this matter that defines 'directly overhead' to include outstretched arms; etc. invites pilots to narrow the margin of the proximity to people with the mindset that even a single foot of clearance is good enough; and as you get comfortable with this interpretation; the risk increases. I believe the regulations need to broaden this definition to include an area around the person; eliminating the black or white nature of the rule. If you are flying over a large group of people close together it becomes much easier to say you are over at least one of them. That was not an issue here.