  Full ray-tracing maps of gravitational lensing, constructed from N-Body
simulations, represent a fundamental tool to interpret present and future weak
lensing data. However the limitation of computational resources and storage
capabilities severely restrict the number of realizations that can be performed
in order to accurately sample both the cosmic shear models and covariance
matrices. In this paper we present a halo model formalism for weak
gravitational lensing that alleviates these issues by producing weak-lensing
mocks at a reduced computational cost. Our model takes as input the halo
population within a desired light-cone and the linear power spectrum of the
underlined cosmological model. We examine the contribution given by the
presence of substructures within haloes to the cosmic shear power spectrum and
quantify it to the percent level. Our method allows us to reconstruct
high-resolution convergence maps, for any desired source redshifts, of
light-cones that realistically trace the matter density distribution in the
universe, account for masked area and sample selections. We compare our
analysis on the same large scale structures constructed using ray-tracing
techniques and find very good agreements both in the linear and non-linear
regimes up to few percent levels. The accuracy and speed of our method
demonstrate the potential of our halo model for weak lensing statistics and the
possibility to generate a large sample of convergence maps for different
cosmological models as needed for the analysis of large galaxy redshift
surveys.
