Left: MSE of the LB-eigenfunction approach, FEM based diffusion solver and Chebyshev polynomial approximation method against the ground truth (σ = 0.01) with different number of eigenfunctions, iterations and expansion degree respectively on the unit sphere with 2562, 10242, 40962, 163842, 655362 and 2621442 mesh vertices. Right: the computational time versus number of mesh vertices at the similar reconstruction error (MSE about 10−5).