Derivative-Based Optical Flow Estimation: Controlled Comparison of First- and Second- Order Methods.

Multi-team tug-of-war game apparatus for two to six teams of one to twelve players per team, with tugging ropes attached to central hub assembly, with appropriate radial orientation on angles of rope. Team players pull ropes in such a manner so as to try to topple their respective goal pieces set a short distance out from game area center. Central hub assembly has a vertically adjustable center pointer rod with central goal contactor attached to it below. Movement of contactor via movement of ropes can topple goal piece for game win. A graphic chart or mat is placed on playing surface to indicate game area center, angles of rope attachment, and location of goal pieces, with the latter two features depending on number of competing teams. In general, novel game permits very large groups, as well as small groups, to play a precision tug-of-war game readily, safely, and inexpensively as measured on a per person basis.