Column density maps for SDC18 (left column) and SDC24 (right column), calculated assuming a single β value in each IRDC. The maps on the top row were generated by smoothing Hi-GAL imaging to a common resolution of 40′′, while those on the bottom utilise the multi-resolution technique, sampling between 40′′ and 13′′ to combine both Herschel and NIKA data. The SDC18 contours show column densities levels of 2.0, 3.5, 5.0, 8.0, 12.0, 17.0 and 23.0 × 10²² cm⁻², and the SDC24 are the same with an additional contour at 1.5 × 10²² cm⁻². Scale bars showing a 1 pc distance are displayed in the top left of each panel.