  Nuclear emulsion is a well-known detector type proposed also for the
directional detection of dark matter. In this paper, we study one of the most
important properties of direction-sensitive detectors: the preservation by
nuclear recoils of the direction of impinging dark matter particles. For
nuclear emulsion detectors, it is the first detailed study where a realistic
nuclear recoil energy distribution with all possible recoil atom types is
exploited. Moreover, for the first time we study the granularity effect on the
emulsion detector directional performance. As well as we compare nuclear
emulsion with other directional detectors: in terms of direction preservation
nuclear emulsion outperforms the other detectors for WIMP masses above 100
GeV/c$^2$.
