The Study of Nebular Emission on Nearby Spiral Galaxies in the IFU Era
  A new generation of wide-field emission-line surveys based on integral field
units (IFU) is allowing us to obtain spatially resolved information of the
gas-phase emission in nearby late-type galaxies, based on large samples of HII
regions and full two-dimensional coverage.These observations are allowing us to
discover and characterise abundance differentials between galactic
substructures and new scaling relations with global physical properties. Here I
review some highlights of our current studies employing this technique: (1) the
case study of NGC 628, the largest galaxy ever sampled with an IFU; (2) a
statistical approach to the abundance gradients of spiral galaxies, which
indicates a universal radial gradient for oxygen abundance; and (3) the
discovery of a new scaling relation of HII regions in spiral galaxies, the
local mass-metallicity relation of star-forming galaxies. The observational
properties and constrains found in local galaxies using this new technique will
allow us to interpret the gas-phase abundance of analogue high-z systems.
