def _region2searchspace(region_point, search_space_resolution):
    """Convert region point to a cube's coordinate in the search space.
    Assume that the search space's origin is at the region coordinate frame's
    origin. The `search_space_resolution` has unit m/cell."""
    return (int(round(region_point[0] / search_space_resolution)),
            int(round(region_point[1] / search_space_resolution)),
            int(round(region_point[2] / search_space_resolution)))