Oita Stadium was chosen as an arena for the World Cup Games in 2002. It is nicknamed "Big Eye" as the stadium's roof opening looks like a human eye.
To enhance the feeling of being part of the soccer arena, the spectator seating was placed right up to the edge of the field. This type of feature would normally be inconvenient for track events, but through a retractable seating system the problem was resolved.
Through the gentle curves of the spherical design, the stadium matches well with the surroundings in the background. The choice of a sphere is naturally an expression of abstract symbolism, but the shape actually enables the retractable portion to move along its surface. The use of ultra-modern teflon membrane panels with 25% light-permeablity removes the need for artificial lighting during daylight hours.
In order for the field to get proper sunlight exposure, the elliptical roof opening runs along the north-south axis. The economical structure of the main beam arch with perpendicular horizontal-running sub-beams corresponds to the elliptical shape of the roof opening.
The pipe-arch structure, as a type of large space frame, is the most reasonable design for this project. The vastness of the site also made this type of structure possible. A slit allowing ventilation is set between the roof and the spectator seating permitting both a view of the mountains and comfort for the summer spectator. The slit also is designed to not create a feeling of being closed inside the stadium.