  Direct photon spectra from central Au+Au- and Cu+Cu-collisions at sqrt(s_NN)
= 62.4, 130 and 200 AGeV are calculated within the microscopic transport model
UrQMD and a micro+macro hybrid model. In the latter approach, the high-density
part of the transport evolution is replaced by an ideal 3+1-dimensional
hydrodynamic calculation. We study the impact of viscosity and full local
thermalization and compare the calculations to measurements obtained by the
PHENIX collaboration. We find a reasonable agreement with the experimental data
for calculations involving a Quark-Gluon-Plasma phase.
