University of Waterloo, Waterloo, Ontario: 16mm.
"Photographs of the construction of a hopper are rapidly shown, and by computer animation, the development of it is portrayed. One side of the hopper is viewed, and a series of rotations show the shape and development of views of the component planes that make up the hopper side. The hopper is reconstructed, and the dihedral angle of the hopper is shown. It is rotated, and the dihedral angle is then shown by a double auxiliary view."