Figure 5.

Synthetic data. Cross sections of three-dimensional conductivity test profiles (left column) and corresponding reconstructions (right column). The test conductivity profiles consist in a homogeneous background of 0.1 S m⁻¹ with a spherical inclusion having a conductivity of 0.15 S m⁻¹, a diameter of 1 cm and a variable position. The inclusion is moved outward along the left 60° radial direction, which corresponds almost to the leftmost edge of the imaging volume (aperture 70° per side). All the simulations have 0.1% additive noise and a single common value for the Tikhonov factor, which has been chosen visually. Test conductivity profiles are plotted on a color scale in the range of 0.1–0.15 S m⁻¹, while reconstructed images are plotted on a color scale covering the range 0.08–0.12 S m⁻¹. (a) Test profile with a 1 cm spherical contrast at 2.75 cm from the axis of the probe. (b) Reconstruction corresponding to the test profile on the left. (c) Test profile with a 1 cm spherical contrast at 3.65 cm from the axis of the probe. (d) Reconstruction corresponding to the test profile on the left. (e) Test profile with a 1 cm spherical contrast at 4.55 cm from the axis of the probe. (f) Reconstruction corresponding to the test profile on the left.