Photometric methods for stellar parameter determinations

A star's effective temperature, effective gravity and metallicity is reflected in its energy distribution and line spectrum. Standard photometric systems have been devised to measure these stellar parameters from the stellar fluxes. The most precise of the standard systems can measure magnitude differences (colours) to between 0.1 and 1%. These colours are generally calibrated empirically using stars of known parameters or by synthetic photometry from model atmospheres. This review will highlight the successes and challenges in synthetic photometry calibrations and the prospective improvement in metallicity sensitivity for halo stars with a new sky survey.