more MPIA dust mapping

At Milky Way Group Meeting at MPIA, Thavisha Dharmawareda (MPIA) showed her first results on building pieces of a three-dimensional dust map from observed extinctions/attenuations to stars. As usual, the problem is to infer a three-dimensional map, preferably non-parametrically, from measurements of line-of-sight integrals through the map. She uses a Gaussian process, variational inference, and inducing points. She has some nice features in her maps (she started with star-formation regions with interesting morphologies). She sees extinction-law variations too; we discussed how those might be incorporated.