  The evolution of topology and morphology of ionized or neutral hydrogen
during different stages of the Epoch of Reionization (EoR) have the potential
to provide us a great amount of information about the properties of the
ionizing sources during this era. We compare a variety of reionization source
models in terms of the geometrical properties of the ionized regions. We show
that the percolation transition in the ionized hydrogen, as studied by tracing
the evolution of the Largest Cluster Statistics (LCS), is a robust statistic
that can distinguish the fundamentally different scenarios -- inside-out and
outside-in reionization. Particularly, the global neutral fraction at the onset
of percolation is significantly higher for the inside-out scenario as compared
to that for the outside-in reionization. In complementary to percolation
analysis, we explore the shape and morphology of the ionized regions as they
evolve in different reionization models in terms of the Shapefinders (SFs) that
are ratios of the Minkowski functionals (MFs). The shape distribution can
readily discern the reionization scenario with extreme non-uniform
recombination in the IGM, such as the clumping model. In the rest of the
reionization models, the largest ionized region abruptly grows only in terms of
its third SF - 'length' - during percolation while the first two SFs -
'thickness' and 'breadth' - remain stable. Thus the ionized hydrogen in these
scenarios becomes highly filamentary near percolation and exhibit a
'characteristic cross-section' that varies among the source models. Therefore,
the geometrical studies based on SFs, together with the percolation analysis
can shed light on the reionization sources.
