Area-integrated parameters computed from the NLFF lower boundary data with different inherent pixel sizes as a function of time for three ARs. Top: unsigned magnetic flux, |Φ_m|. Bottom: unsigned vertical current, |I_z|. Red, blue, and green colors correspond to bin1, bin2, and bin4 data, respectively, with inherent plate scales of ∼0.36, ∼0.72, and ∼1.4 Mm. Vertical bars indicate the impulsive phase of X-class flares that occurred during the time intervals analyzed. Empty symbols mark disqualifying NLFF solutions (see Sect. 3.1 for explanation).