The pilot of a glider reported that during the landing roll, near the location where he wanted to stop, he felt a "thump." He further reported that he observed a person lying on the ground on the runway and did not see the bystander previously. According to the pilot-rated passenger, who was also the airport manager, the bystander was taking photographs of the glider and had moved onto the runway surface during the landing roll. Subsequently, the bystander was struck by the left wing. He further reported that he also did not see the bystander before the collision. The airport manager reported that the airport had a sign near the runway, which stated "Caution Aircraft Operations." Postaccident, the airport manager reported that he installed cones delineating the boundary of the runway and added an additional sign stating "Remain Behind Cones." The bystander sustained a serious injury. The pilot reported no preaccident mechanical malfunctions or failures with the glider that would have precluded normal operation.