Consecutive differences in projection area of generated cone ensemble (red, left Y-axis) and ratio of dimming area in projection to the total area of projection (blue, right Y-axis) in percentage at the end of the impulsive phase of the 1 October, 2011 event. Vertical dashed line indicates the step (associated cone height of 1.04 R_sun, width of 48.7° and inclination angle of 24.3°) where consecutive differences reach 5% of the maximum of the cone projection area, which also lies within 95% of the maximum percentage of the dimming area in projection.