  We present a scheme of the high-precise three-dimensional (3D) localization
by the measurement of the atomic-level population. The scheme is applied to a
four-level tripod-type atom coupled by three strong standing waves and a probe
running wave. As a result, the atom can be localized in volumes that are
substantially smaller than a cubic optical wavelength. The upper-level
distribution depends crucially on the atom-field coupling and it forms 3D
periodic structures composed of spheres, hourglasses, bowls, donuts, or
deformed barrels.
