Local dust overdensities relative to surrounding matter in the REDLINE map. To highlight regions where dust density significantly deviates from the ambient material, the map of the Galactic plane was first lightly smoothed and then a heavily smoothed version was subtracted from it. This technique enhances local density variations, effectively isolating overdense features from the broader background. The overlaid spiral arms are the result of a fit to the data and are explained in Sect. 4.2.2.