Fig. 1.

(a) (Media 1 ^{(3.9MB, AVI)} ) Three twisted spirals built from scattering balls are embedded in a weakly scattering cylinder with background transport coefficient μ =0.1 mm⁻¹ and albedo λ = 0.999. Value of the transport coefficient for each scattering ball is set to μ = 0.75 mm⁻¹. Two spirals have the background value of the albedo and one absorbing spiral has the value of albedo λ = 0.25. The direct light enters the domain along the direction s₀ = 2^−1/2 (1,0,−1)^T. Camera was rotated around the weakly scattering cylinder, whose axis is aligned along z-axis, by 153° with respect to the initial position n = (1,0,0)^T, where n is the camera normal. (b) (Media 2 ^{(3.3MB, AVI)} ) Two highly scattering cylinders are embedded in a weakly scattering cylinder with the same optical properties as in (a). Both highly scattering cylinders have μ = 0.75 mm⁻¹, one of them has a low value of the albedo, λ = 0.25. The direct light enters the domain along the same direction as in (a).The camera was rotated by 117° from its initial position around z-axis in the positive direction.