1. A method of generating an acceleration structure in a ray tracing system to generate object data for display of objects seen from a viewpoint of a camera, the method comprising: assigning the objects into bounding boxes; generating an acceleration structure comprising nodes, the acceleration structure indicating inclusion relationships between the bounding boxes; and marking overlapping nodes among the nodes by adding a flag to each of the nodes, wherein the flag of a node among the nodes indicates whether child nodes of the node correspond to overlapping bounding boxes among the bounding boxes, and indicating overlap information at an upper node closest to the child nodes indicating the overlapping bounding boxes.