A method of determining rotation and scale transformation parameters is disclosed. The insulation products include randomly distributed inorganic fibers, which are supplemented with at least about five weight percent microspheres, macrospheres, or both, and preferably include hollow microspheres, which boost the insulation value of the fiberglass thermal insulation by at least about 0. This free propagation area has a first portion increasing its width from the input waveguide toward the first slab waveguide and a second portion having the width larger than that of the input waveguide. These dimples may be circular or polygonal in shape.