$R_V^{\mathrm{\prime }}$ values for APOGEE targets from Schlafly et al. (2016) (top) and extinction-normalized DIB for the same LOSs (bottom) in Galactic coordinates. The sizes of the markers were reduced for LOS extinctions beyond 4 mag. The limited resolution of the 3D maps is responsible for the slightly smoother image for the normalized DIB. There is a some similarity between the two independent measurements, with notable exceptions, e.g. in the Aquila region (l = 0°, b = +5°, +15°), and Taurus (l = 160°, b = −15° or b = −22°) characterized by a strong opacity.