A three-dimensional Galactic extinction model

A large-scale three-dimensional model of Galactic extinction is presented based on the Galactic dust distribution model of Drimmel and Spergel (2001). The extinction A_V to any point within the Galactic disk can be quickly deduced using a set of three-dimensional cartesian grids. Extinctions from the model are compared to empirical extinction measures, including lines-of-sight in and near the Galactic plane using optical and NIR extinction measures; in particular we show how extinction can be derived from NIR color-magnitude diagrams in the Galactic plane to a distance of 8 kiloparsec.