Figure 3. Studying z-gap and number of z-slices.

a, Using simulated scaffolds of 100 μm diameter particles to mimic microscope data, we approximate VVF using average void area fraction across 2-D z-slices and report how the relative accuracy of the approximation changes as a function of the step size (z-gap) taken. Z-slices are sampled within the middle 50% of each scaffold. A z-gap of less than ~15 μm ensures a stable approximation of VVF that stays within 7% accuracy for all scaffolds across all magnifications. b, We again plot the relative accuracy of average void area fraction compared to the true VVF, but this time we hold the z-gap constant at 13 μm and incrementally increase the number of z-slices starting at the bottom of the scaffold. Sampling 20 or more z-slices ensures a stable approximation of VVF that stays within 4% accuracy for all scaffolds across all magnifications. N = 5 domains. The true VVF for each scaffold at each magnification is reported in Supplementary Table 1.