When positive, there is a crossover point. When negative the bulb simply bulges out of the plane like a pimple. Higher values make the top end of the bulb fatter. The 2d strophid curve can be extruded in the Z direction or rotated about various axes by using the SOR parameters. Larger values give larger bulbs.
Negative values give a bulb on the other side of the plane.
When zero, the bulb is like a sphere that just touches the plane. When positive, there is a crossover point. When negative the bulb simply bulges out of the plane like a pimple. Higher values make the top end of the bulb fatter. The height of the spike is always about 1 unit.