Simulated void space and corresponding leak areas: (a) and (b) are training void space data with $σ=0,0.05$⁠, respectively, (c) is training leak areas, (d) and (e) are test void space data with $σ=0,0.05$⁠, respectively, and (f) is test leak areas (the color/gray scale bars in (a), (b), (d), and (e) reflect the magnitude of void space)