  We present a method for photometric selection of metal-poor halo giants from
the imaging data of the Sloan Digital Sky Survey (SDSS). These stars are offset
from the stellar locus in the (g-r) vs. (u-g) color-color diagram. Based on a
sample of 29 candidates for which spectra were taken, we derive a selection
efficiency of the order of 50%, for stars brighter than $r \sim 17^m$. The
candidates selected in 400 deg$^2$ of sky from the SDSS Early Data Release
trace the known halo structures (tidal streams from the Sagittarius dwarf
galaxy, the Draco dwarf spheroidal galaxy), indicating that such a
color-selected sample can be used to study the halo structure even without
spectroscopic information. This method, and supplemental techniques for
selecting halo stars, such as RR Lyrae stars and other blue horizontal branch
stars, can produce an unprecedented three-dimensional map of the Galactic halo
based on the SDSS imaging survey.
