  We present a three dimensional map of extinction in the Northern Galactic
Plane derived using photometry from the IPHAS survey. The map has fine angular
($\sim 10$ arcmin) and distance (100 pc) sampling allied to a significant depth
($\gtrsim 5$ kpc). We construct the map using a method based on a hierarchical
Bayesian model as previously described by Sale (2012). In addition to mean
extinction, we also measure differential extinction, which arises from the
fractal nature of the ISM, and show that it will be the dominant source of
uncertainty in estimates of extinction to some arbitrary position. The method
applied also furnishes us with photometric estimates of the distance,
extinction, effective temperature, surface gravity, and mass for $\sim 38$
million stars. Both the extinction map and the catalogue of stellar parameters
are made publicly available via http://www.iphas.org/extinction .
