Space missions such as Kepler, K2, and TESS have produced exquisite data for exoplanet research, and forthcoming missions like PLATO and Earth 2.0 will continue to discover thousands of new exoplanets. A uniform characterisation of these exoplanets, which are situated in various fields, is required for statistical analyses. Although Gaia parallaxes have become publicly accessible to derive stellar parameters (such as radius) for exoplanet hosts, homogeneous interstellar extinction measurements for the transit survey fields have yet to be developed. In this talk, I will present our open-source approach, spectral energy distribution fitting, to estimate extinction by combining data from large-volume photometric and spectroscopic surveys.  I will also introduce our scheme to create 3D dust maps for the fields. Our extinction maps will be beneficial for exoplanet research and asteroseismic analysis.