Tennis polo
The sport is played on a grass field between 80 and 100 yards long and 50 to 65 yards wide. The goal area is a semicircular line with an 11-yard radius and the penalty mark at 13 yards from the goal. An experimental rule has a second semicircular line on the field with a 17-yard radius. Generally, a field for gridiron football or soccer can be used.
RoboCup Small Size League
Two teams of six robots which are limited to an 18 cm diameter and 15 cm height play soccer with an orange golf ball. They are identified and tracked by four overhead cameras connected to an off-field computer. The field size is 9metersx6meters. Then robots' and balls' status including their position and id are sent to teams' computers. Their AI software sends commands to the robots based on the vision data.