  In this paper, as a preparation of developing data analysis procedures for
using 3-dimensional information offered by directional Dark Matter (DM)
detection experiments, we study the patterns of the angular distribution of the
Monte Carlo-generated 3-D velocity of halo Weakly Interacting Massive Particles
(WIMPs) as well as apply the Bayesian fitting technique to reconstruct the
radial distribution of the 3-D WIMP velocity. Besides the diurnal modulation of
the angular WIMP velocity distribution, the so-called "directionality" of DM
signals proposed in literature, we will also demonstrate possible "annual"
modulations of both of the angular and the radial distributions of the 3-D WIMP
velocity. Our Bayesian reconstruction results of (the annual modulation of) the
radial WIMP velocity distribution will also be discussed in detail. For
readers' reference, the angular distribution patterns of the 3-D WIMP velocity
in the "laboratory (location)-dependent" reference frames of several
underground laboratories are given in the Appendix.
