As a general rule of thumb, it’s recommended to obtain signed image releases from participants in situations where it is not impractical or overly burdensome, especially when students or online usage of images is involved.
For large public events with minimal expectation of privacy, like football games or concerts, individual releases aren't typically required except when using specific, recognizable images of individuals, particularly students, due to privacy concerns.
It's recommended to display event signage to inform participants about recording and image usage at large semi-private or internal events as well as at large public events.
Legal Affairs has prepared specific language for such signage. Refer to Event Signage Language doc link on Forms page.