  Radiation of dileptons and photons from high energy nuclear collisions
provides information on the space-time evolution of the hot dense matter
produced therein. We compute this radiation using relativistic hydrodynamics
and a coarse-grained version of the microscopic event generator UrQMD, both of
which provide a good description of the hadron spectra. The currently most
accurate dilepton and photon emission rates from perturbative QCD and from
experimentally-based hadronic calculations are used. Comparisons are made to
data on central Pb-Pb and Pb-Au collisions taken at the CERN SPS at a beam
energy of 158 A GeV. Both hydrodynamics and UrQMD provide very good
descriptions of the photon transverse momentum spectrum measured between 1 and
4 GeV, but slightly underestimate the low mass spectrum of e+e- pairs, even
with greatly broadened rho and omega vector mesons. Predictions are given for
the transverse momentum distribution of dileptons.
