  Large area field electron emitters, typically consisting of several thousands
of nanotips, pose a major challenge since numerical modeling requires enormous
computational resources. We propose a hybrid approach where the local
electrostatic field enhancement parameters of an individual emitter is
determined numerically while electrostatic shielding and anode-proximity
effects are incorporated using recent analytical advances. The hybrid model is
tested numerically on an ordered arrangement of emitters and then applied to
recent experimental results on randomly distributed gold nanocones. Using the
current-voltage data of two samples with vastly different emitter densities but
having similar nanocone sizes, we show that an appropriate modeling of the
emitter-apex together with the analytical results on shielding and
anode-proximity effects, leads to consistent results for the apex radius of
curvature. In both cases, the $\text{I-V}$ data is approximately reproduced for
$R_a \simeq 9$nm. Importantly, it is found that anode-proximity plays a
significant role in counter-balancing electrostatic shielding and ignoring this
effect results in the requirement of a much smaller value of $R_a$.
