  We address light propagation properties in complex media consisting of random
distributions of lenses that have specific focusing properties. We present both
analytical and numerical techniques that can be used to study emergent
properties of light organization in these media. As light propagates, it
experiences multiple scattering leading to the formation of light bundles in
the form of branches; these are random yet occur systematically in the the
medium, particularly in the weak scattering limit. On the other hand, in the
strong scattering limit we find that coalescence of branches may lead to the
formation of extreme waves of the "rogue wave" type. These waves appear at
specific locations and arise in the linear as well as in the nonlinear regimes.
We present both the weak and strong scattering limit and show that these
complex phenomena can be studied numerically and analytically through simple
models.
