Reconstruction of an isotropically turbulent 3D magnetic field within a cube of side L = 3 kpc. Top: the ground truth; an isotropically turbulent GMF with an RMS magnitude of 5 µG. The colormap denotes the vector’s magnitude. Middle: local data sampled uniformly. The mean distance between each data point is 300 pc. The colormap is saturated at the maximum magnitude that appears in Fig. 6a. Bottom: the mean of the approximating Gaussian posterior distribution attained via the geoVI algorithmn based on the data provided in Fig. 6b.